Article

The folate precursor para-aminobenzoic acid elicits induced resistance against Cucumber mosaic virus and Xanthomonas axonopodis

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Abstract

Background and AimsThe use of vitamins including vitamin B1, B2 and K3 for the induction of systemic acquired resistance (SAR) to protect crops against plant pathogens has been evaluated previously. The use of vitamins is beneficial because it is cost effective and safe for the environment. The use of folate precursors, including ortho-aminobenzoic acid, to induce SAR against a soft-rot pathogen in tobacco has been reported previously.Methods In the present study, para-aminobenzoic acid (PABA, also referred to as vitamin Bx) was selected owing to its effect on the induction of SAR against Xanthomonas axonopodis pv. vesicatoria in pepper plants through greenhouse screening.Key ResultsDipping of pepper seedlings in a 1 mm PABA solution in field trials induced SAR against artificially infiltrated X. axonopodis pv. vesicatoria and naturally occurring cucumber mosaic virus. Expression of the Capsicum annuum pathogenesis-related 4 gene was primed in response to pathogen infection as assessed by quantitative real-time PCR. The accumulation of cucumber mosaic virus RNA was reduced in PABA-treated pepper plants at 40 and 105 d post-treatment. Unexpectedly, fruit yield was increased in PABA-treated plants, indicating that PABA-mediated SAR successfully protected pepper plants from infection by bacterial and viral pathogens without significant fitness allocation costs.Conclusions The present study is the first to demonstrate the effective elicitation of SAR by a folate precursor under field conditions.

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... Disease severity in leaves was assessed 7-10 day after pathogen challenge using the following scale: 0, no symptoms; 1, yellowish color; 2, chlorosis only; 3, necrosis and chlorosis; 4, partial necrosis of the inoculated area; and 5, complete necrosis of the inoculated area (Yi et al. 2013). Numbers of bacteria were measured at 0, 3, and 7 days after pathogen infiltration, as described previously (Song et al. 2013a). Each treatment was applied to eight plants and the experiment was repeated three times. ...
... Severity of naturally occurring CMV was assessed on a 0-5 scale as follows: 0 = no symptoms; 1 = mild deformation and mosaic of the youngest two leaves; 2 = pronounced leaf deformation and mosaic of the youngest two leaves with progression of symptoms into sequentially older leaves; 3 = pronounced leaf deformation and mosaic progression beyond the two youngest leaves with all leaves expressing some form of CMV-induced symptoms; 4 = similar symptoms as described for a rating of 3, with plants also being stunted in growth (where stunting includes both reduced internode extension and smaller leaves); and 5 = severe stunting with the majority of leaves being small, severely deformed, and tightly bunched together (Song et al. 2013a). ...
... PCR reactions were performed according to the manufacturer's instructions. The expression of candidate priming genes was analyzed using the following primers: 5′-ACTTGCAATTATGA (Song et al. 2013a;Yang et al. 2009Yang et al. , 2011. CaActin was used as a control, and was assessed using the following primers: 5′-CACTGA AGCACCCTTGAACCC-3′ and 5′-GAGACAACACCGCC TGAATAGC-3′. ...
Article
Plants are defended from attack by emission of volatile organic compounds (VOCs) that can act directly against pathogens and herbivores or indirectly by recruiting natural enemies of herbivores. However, microbial VOC have been less investigated as potential triggers of plant systemic defense responses against pathogens in the field. Bacillus amyloliquefaciens strain IN937a, a plant growth-promoting rhizobacterium that colonizes plant tissues, stimulates induced systemic resistance (ISR) via its emission of VOCs. We investigated the ISR capacity of VOCs and derivatives collected from strain IN937a against bacterial spot disease caused by Xanthomonas axonopodis pv. vesicatoria in pepper. Of 15 bacterial VOCs and their derivatives, 3-pentanol, which is a C8 amyl alcohol reported to be a component of sex pheromones in insects, was selected for further investigation. Pathogens were infiltrated into pepper leaves 10, 20, 30, and 40 days after treatment and transplantation to the field. Disease severity was assessed 7 days after transplantation. Treatment with 3-pentanol significantly reduced disease severity caused by X. axonopodis and naturally occurring Cucumber mosaic virus in field trials over 2 years. We used quantitative real-time polymerase chain analysis to examine Pathogenesis-Related genes associated with salicylic acid (SA), jasmonic acid (JA), and ethylene defense signaling. The expression of Capsicum annuum Pathogenesis-Related protein 1 (CaPR1), CaPR2, and Ca protease inhibitor2 (CaPIN2) increased in field-grown pepper plants treated with 3-pentanol. Taken together, our results show that 3-pentanol triggers induced resistance by priming SA and JA signaling in pepper under field conditions.
... In addition, we observed an apparently EDS1-independent accumulation of the folate precursors 7,8-dihydropteroate (DHP) and 4-amino-4deoxychorismate (ADC; Fig. 1) after Fourier transform ion cyclotron resonance-mass spectrometry (FTICR-MS) analysis of extracts from AvrRpm1-expressing plants (data not shown). These compounds caught our attention because folates may promote plant growth and/or yield (Burguieres et al., 2007;Song et al., 2013), whereas the chloroplastic folate precursor para-aminobenzoic acid (PABA; Fig. 1) enhances resistance in pepper to Xanthomonas axonopodis and Cucumber mosaic virus (Song et al., 2013). ...
... In addition, we observed an apparently EDS1-independent accumulation of the folate precursors 7,8-dihydropteroate (DHP) and 4-amino-4deoxychorismate (ADC; Fig. 1) after Fourier transform ion cyclotron resonance-mass spectrometry (FTICR-MS) analysis of extracts from AvrRpm1-expressing plants (data not shown). These compounds caught our attention because folates may promote plant growth and/or yield (Burguieres et al., 2007;Song et al., 2013), whereas the chloroplastic folate precursor para-aminobenzoic acid (PABA; Fig. 1) enhances resistance in pepper to Xanthomonas axonopodis and Cucumber mosaic virus (Song et al., 2013). ...
... For example, elevated folate content in rice seeds is associated with the induction of defence-related genes, including a number of NLR receptors, such as RPM1 (Blancquaert et al., 2013b). In addition, PABA-induced resistance in pepper to X. axonopodis and Cucumber mosaic virus is associated with the induction of SA-related PR genes (Song et al., 2013). We show here that the folate precursor DHN and folic acid induce local and systemic SA-mediated defence in Arabidopsis, and suggest that folic acid suppresses JA-mediated responses to A. brassicicola. ...
Article
Folates are essential for one-carbon transfer reactions in all organisms and contribute for example to de novo DNA synthesis. Here, we detected the folate precursors 7,8-dihydropteroate (DHP) and 4-amino-4-deoxychorismate (ADC) in extracts from Arabidopsis thaliana plants by Fourier transform ion cyclotron resonance mass spectrometry. The accumulation of DHP but not ADC was induced after infection of plants with Pseudomonas syringae delivering the effector protein AvrRpm1. Application of folic acid or the DHP precursor 7,8-dihydroneopterin enhanced resistance in Arabidopsis to P. syringae and elevated the transcript accumulation of the salicylic acid (SA) marker gene PATHOGENESIS-RELATED1 both in the treated and systemic untreated leaves. DHN- and folic acid-induced systemic resistance was dependent on SA biosynthesis and signaling. Similarly to SA, folic acid application locally enhanced Arabidopsis susceptibility to the necrotrophic fungus Alternaria brassicicola. Together, the data associate the folic acid pathway with innate immunity in Arabidopsis, simultaneously activating local and systemic SA-dependent resistance to P. syringae and suppressing local resistance to A. brassicicola.
... The protection by PGPR was maintained up to 40 days after transfer to the field. These findings point to the potential to develop a commercial biopreparation to manage viral diseases (Song et al. 2013). Furthermore, the commercial formulation of two PGPR mixtures also led to successful protection of tomato against CMV (Murphy et al. 2003). ...
... Mutants of P. fluorescens CHA0 and S. macerans 90-166 deficient in SA production showed similar levels of plant protection to the virus compared with the wild type, indicating that ISR induction functions in an SA-independent manner (Maurhofer et al. 1994;Press et al. 2001). Recently, pepper seedlings subjected to drench application of bacterial volatile compounds and their derivatives showed reduced symptom development and viral accumulation caused by CMV (Choi et al. 2014;Song et al. 2013). ...
... In addition, signal transduction from belowground to aboveground plant parts when the virus is transmitted into the plant cell leads to inconsistent results when the beneficial effects of PGPR are introduced. Nonetheless, in these field and greenhouse trials, bacteria and their byproducts exhibited the potential to control viral diseases without reducing plant growth (Song et al. 2013). ...
Article
Beneficial plant-associated bacteria protect host plants against pathogens, including viruses. However, leaf-associated (phyllosphere) bacteria have rarely been investigated as potential triggers of plant systemic defense against plant viruses. We found that leaf-colonizing Bacillus amyloliquefaciens strain 5B6 (isolated from a cherry tree leaf) protected Nicotiana benthamiana and pepper plants against Cucumber mosaic virus (CMV). In a field trial, treatment with strain 5B6 significantly reduced the relative contents of CMV coat protein RNA compared with the water control over a 3-year period, as revealed by quantitative reverse-transcription polymerase chain reaction. The expression of Capsicum annuum pathogenesis-related (PR) genes CaPR4, CaPR5, and CaPR10 was upregulated in field-grown pepper plants treated with strain 5B6. In addition, the accumulation of two naturally occurring viruses, Broad bean wilt virus and Pepper mottle virus, was reduced by foliar treatment with strain 5B6, which is similar to the results for benzothiadiazole treatment as a positive control. Taken together, the results suggest that strain 5B6 has strong potential for protecting plants against viruses by increasing defense priming of salicylic acid and jasmonic acid signaling in pepper under field conditions. This is the first report of the protection of a plant against viral diseases by foliar application of leaf-associated bacilli.
... To overcome this pitfall, researchers have attempted to identify compounds that induce resistance without reducing plant growth in the field (Reglinski et al. 2013;Cipollini and Heil 2010;Boubakri et al. 2015). In this context, some vitamins were identified to act as inducers of disease resistance and have received an important attention owing to their safety and cost effectiveness (Cipollini and Heil 2010;Dong and Beer 2000;Lyon 2007;Song et al. 2013). In fact, different vitamins were shown to induce resistance against a wide range of pathogens (fungus, bacteria and viruses) in arabidopsis, rice, cucumber, tobacco, grapevine, and tomato (Dong and Beer 2000;Dong 2001;Ahn et al. 2005;Saikia et al. 2006;Tarighi 2010, 2011;Azami-Sardooei et al. 2010;Boubakri 2013;Boubakri et al. 2012Boubakri et al. , 2013aLiu et al. 2010). ...
... PABA is known to control fungal pathogens in China (Table 1), but the implicated mechanisms, such as a possible induction of host-defense responses, was not studied (Kelman and Cook 1977). Recently, PABA was identified to be capable of inducing SAR against bacterial and viral diseases in pepper plants (Yang et al. 2011;Song et al. 2013). PABA is the only vitamin that was found to be able to induce resistance against a viral disease caused by Cucumber mosaic virus (CMV). ...
... PABA is the only vitamin that was found to be able to induce resistance against a viral disease caused by Cucumber mosaic virus (CMV). Besides of its role in inducing resistance to both Cucumber mosaic virus and Xanthomonas axonopodis, PABA was found to enhance pepper plant yield under field conditions in a simultaneous manner (Song et al. 2013). In the same study, BTH which, reduced disease progress, provoked a shortening of plant shoots and also a reduction in fruit weight when compared to both the PABA-treated samples and controls. ...
Article
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Main conclusion This paper provides an overview on vitamins with inducing activities in plants, the molecular and cellular mechanisms implicated, and the hormonal signalling-network regulating this process. Moreover, it reports how vitamins might be part of the molecular events linked to induced resistance by the conventional elicitors. Induced resistance (IR), exploiting the plant innate-defense system is a sustainable strategy for plant disease control. In the last decade, vitamins have been proven to act as inducers of disease resistance, and these findings have received an important attention owing to their safety and cost effectiveness. Vitamins, including thiamine (TH, vitamin B1), riboflavin (RF, vitamin B2), menadione sodium bisulfite (MSB, vitamin K3), Para-aminobenzoic acid (PABA, vitamin Bx), and folic acid (FA, vitamin B9) provided an efficient protection against a wide range of pathogens through the modulation of specific host-defense facets. However, other vitamins, such as ascorbic acid (AA, vitamin C) and tocopherols (vitamin E), have been shown to be a part of the molecular mechanisms associated to IR. The present review is the first to summarize what vitamins are acting as inducers of disease resistance in plants and how could they be modulated by the conventional elicitors. Thus, this report provides an overview on the protective abilities of vitamins and the molecular and cellular mechanisms underlying their activities. Moreover, it describes the hormonal-signalling network regulating vitamin-signal transduction during IR. Finally, a biochemical model describing how vitamins are involved in the establishment of IR process is discussed.
... vesicatoria growth on agar medium by strain RGJ1, indicating that RGJ1 may induce systemic resistance in pepper plants to protect against bacterial spot disease. Yeast-mediated induced systemic resistance (ISR) was accompanied by the expression of defense priming genes, including Capsicum annuum Pathogenesis-Related (CaPR) 4 for SA/JA signaling and CaPR5 for ethylene signaling 21,[37][38][39][40] . Unexpectedly, field spray application of strain RGJ1 on pepper plants significantly reduced the symptoms caused by several viruses, including CMV, Pepper mottle virus (PepMoV), Pepper mild mottle virus (PMMoV), and Broad bean wilt virus (BBWV). ...
... Defense priming of pathogenesis-related genes. Defense priming is an important feature of induced resistance 13,21,37,39,42,43 . To confirm that foliar spray application of strain RGJ1 elicits plant-induced resistance and defense priming, the expression of the defense-related genes CaPR4 for SA/JA signaling and CaPR5 for ethylene signaling after 0 and 6 h of pathogen challenge was examined by quantitative reverse transcription PCR (qRT-PCR) after 0 and 6 h of pathogen challenge under field conditions. ...
... whether strain RGJ1 induces ISR under field conditions, we examined plants for symptoms of bacterial spot disease 5-10 days after infection 37,39,43 . We used a quantitative disease index to determine the disease symptom severity in infected plants that were either mock-treated or treated with RGJ1, or BTH. ...
Article
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Yeast associates with many plant parts including the phyllosphere, where it is subject to harsh environmental conditions. Few studies have reported on biological control of foliar pathogens by yeast. Here, we newly isolated leaf-colonizing yeasts from leaves of field-grown pepper plants in a major pepper production area of South Korea. The yeast was isolated using semi-selective medium supplemented with rifampicin to inhibit bacterial growth and its disease control capacity against Xanthomonas axonopodis infection of pepper plants in the greenhouse was evaluated. Of 838 isolated yeasts, foliar spray of Pseudozyma churashimaensis strain RGJ1 at 10⁸ cfu/mL conferred significant protection against X. axonopodis and unexpectedly against Cucumber mosaic virus, Pepper mottle virus, Pepper mild mottle virus, and Broad bean wilt virus under field conditions. Direct antagonism between strain RGJ1 and X. axonopodis was not detected from co-culture assays, suggesting that disease is suppressed via induced resistance. Additional molecular analysis of the induced resistance marker genes Capsicum annuum Pathogenesis-Related (CaPR) 4 and CaPR5 indicated that strain RGJ1 elicited plant defense priming. To our knowledge, this study is the first report of plant protection against bacterial and viral pathogens mediated by a leaf-colonizing yeast and has potential for effective disease management in the field.
... For instance, Paraaminobenzoic acid (PABA), which is a cyclic amino acid that belongs to the vitamin B group, was able to induce SAR in pepper against cucumber mosaic virus (CMV) and Xanthomonas axonopodis pv. vesicatoria through SA pathway [58]. The substituted benzoates, 3-chlorobenzoic acid and 3,5dichlorobenzoic acid induced basal defense against H. parasitica in A. thaliana [54]. ...
... For instance, Para-aminobenzoic acid (PABA), which is a cyclic amino acid that belongs to the vitamin B group, was able to induce SAR in pepper against cucumber mosaic virus (CMV) and Xanthomonas axonopodis pv. vesicatoria through SA pathway [58]. The substituted benzoates, 3-chlorobenzoic acid and 3,5-dichlorobenzoic acid induced basal defense against H. parasitica in A. thaliana [54]. ...
... Pepper/CMV, Xanthomonas axonopodis pv. Vesicatoria (Laboratory) [58] 3.3. Nicotinic Acid Derivatives: 2,6-dichloro-isonicotinic Acid (INA) and N-cyanomethyl-2-chloro isonicotinic Acid (NCI) ...
Article
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Functional analogues of salicylic acid are able to activate plant defense responses and provide attractive alternatives to conventional biocidal agrochemicals. However, there are many problems that growers must consider during their use in crop protection, including incomplete disease reduction and the fitness cost for plants. High-throughput screening methods of chemical libraries allowed the identification of new compounds that do not affect plant growth, and whose mechanisms of action are based on priming of plant defenses, rather than on their direct activation. Some of these new compounds may also contribute to the discovery of unknown components of the plant immune system.
... The seedlings treated with 10 mM and 15 mM of benzoic acid achieved 100% disease reduction. This was in agreement with studies conducted in Capsicum annuum against cucumber mosaic virus and Xanthomonas axonopodis (Song et al., 2013) and also in cucumber plants against Colletotrichum lagenarium (Song et al., 2013). The benzoic acid treated seedlings performed better than the salicylic treated seedlings in the current findings. ...
... The seedlings treated with 10 mM and 15 mM of benzoic acid achieved 100% disease reduction. This was in agreement with studies conducted in Capsicum annuum against cucumber mosaic virus and Xanthomonas axonopodis (Song et al., 2013) and also in cucumber plants against Colletotrichum lagenarium (Song et al., 2013). The benzoic acid treated seedlings performed better than the salicylic treated seedlings in the current findings. ...
... vesicatoria and to cucumber mosaic virus. The fruit yield, increased against this background, indicates the absence of competitive relations between the induced mechanisms of adaptation and natural course of ontogeny (Song et al., 2013). ...
... The increased germinative capacity of Scots pine under the impact of PABA in tested concentrations described previously (Ivanov, 1988) was confirmed in experiments with seeds of different plant species (Eigers et al., 2012;Aliev and Sivolapov, 2013;Bekusarova et al., 2013). The physiological mechanisms underlying this phenomenon were identified and described in detail (Camara et al., 2012;Song et al., 2013). ...
Article
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This article summarizes 27 years of observations on the growth status of Scots pine artificial stands established after treating seeds with para-aminobenzoic acid (concentration range: 3.7–18.2 mM) one time. A long-term stimulating effect of PABA on the height growth (up to 47%) and diameter (up to 42%) of artificial stands is discovered. By the age of 27 years, self-pruning of the artificial stands increased by 18%. Possible mechanisms of long-term PABA physiological effect are now being discussed.
... Dipping pepper seedlings in a solution containing para-aminobenzoic acid (vitamin Bx) in field trials induced SAR and successfully protected pepper plants against Xanthomonas axonopodis pv. vesicatoria, without significant fitness allocation costs (Song et al. 2013). In addition to their beneficial effects on disease suppression, vitamins can also increase growth parameters as well as yields in treated plants (Song et al. 2013). ...
... vesicatoria, without significant fitness allocation costs (Song et al. 2013). In addition to their beneficial effects on disease suppression, vitamins can also increase growth parameters as well as yields in treated plants (Song et al. 2013). ...
Chapter
Plant resistance inducers, also referred to as elicitors, are agents that confer improved protection to pathogen or pest attacks by inducing host defense mechanisms. Such products are effective against a wide range of crop enemies, including viruses, bacteria, fungi, oomycetes, nematodes, and herbivores. The mode of action of these products differs from that of traditional pesticides because they do not target directly the bio-aggressor through antifungal activity, but they inhibit its development indirectly via the elicitation of plant defense reactions. In the current context of sustainable agriculture and growing demand for healthy food, plant resistance inducers are considered as an eco-friendly and promising alternative to conventional pesticides, and their implementation in integrated pest management strategy is strongly encouraged. Plant resistance inducers can be of synthetic or natural origin. This chapter will focus on resistance inducers of natural origin including living microorganisms, plant extracts, microbial cell-wall extracts, microbial metabolites, minerals, and ions. An overview on the market and recent advances on the regulation of these products as well as future challenges to promote their development and wide use in disease management programs will be described.
... B. amyloliquefaciens strain IN937a was recently shown to stimulate systemic resistance due to the release of bacterial volatile compounds (BVCs) (Kloepper et al., 2004b;Ryu et al., 2004;Choi et al., 2014). Treatment with BVCs from PGPR reduced symptom development and CMV accumulation in pepper seedlings (Song et al., 2013;Choi et al., 2014). BVCs are important chemicals in plant virus control because they can affect plant resistance and can be applied on a wide range of scales (Kesselmeier and Staudt, 1999;Ryu et al., 2004;Kai et al., 2009). ...
... To analyze the expression of defense-priming genes, the expression of candidate priming genes was analyzed using the primers shown in Table 1 (Yang et al., 2009(Yang et al., , 2011Song et al., 2013). The expression of defense-priming genes in pepper leaves was analyzed using the same leaves sample as the assay of viral disease. ...
Article
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The volatile compound 2,3-butanediol, which is produced by certain strains of root-associated bacteria, consists of three stereoisomers, namely, two enantiomers (2R,3R- and 2S,3S-butanediol) and one meso compound (2R,3S-butanediol). The ability of 2,3-butanediol to induce plant resistance against pathogenic fungi and bacteria has been investigated; however, little is known about its effects on induced resistance against viruses in plants. To investigate the effects of 2,3-butanediol on plant systemic defense against viruses, we evaluated the disease control capacity of each of its three stereoisomers in pepper. Specifically, we investigated the optimal concentration of 2,3-butanediol to use for disease control against Cucumber mosaic virus and Tobacco mosaic virus in the greenhouse and examined the effects of drench application of these compounds in the field. In the field trial, treatment with 2R,3R-butanediol and 2R,3S-butanediol significantly reduced the incidence of naturally occurring viruses compared with 2S,3S-butanediol and control treatments. In addition, 2R,3R-butanediol treatment induced the expression of plant defense marker genes in the salicylic acid, jasmonic acid, and ethylene signaling pathways to levels similar to those of the benzothiadiazole-treated positive control. This study reports the first field trial showing that specific stereoisomers of 2,3-butanediol trigger plant immunity against multiple viruses.
... tomato DC3000 (Pst) elicitors. In addition, p-aminobenzoic acid (PABA), which belongs to the vitamin B group [41], and menadione sodium bisulphite (MSB), a vitamin K3 derivative [42], act as inducers by a priming mechanism. There are reports that support the central role of reactive oxygen species, particularly H 2 O 2 , in vitamin-induced resistance (vitamin-IR), and that ascorbic acid (vitamin C) and tocopherols (vitamin E) form part of the molecular mechanisms that underlie this IR [43]. ...
... Riboflavin-IR to P. viticola in grapevine involves H 2 O 2 accumulation [46] and callose deposition, which prevent the pathogen and its toxins from entering [44]. PABA is capable of priming resistance against Cucumber mosaic virus and Xanthomonas axonopodis by inducing SAR [41]. MSB generates H 2 O 2 and primes genes in Arabidopsis plants like several GSTs and those that encode ABC transporters, which may maintain oxidative homeostasis [47]. ...
Article
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Priming by natural compounds is an interesting alternative for sustainable agriculture, which also contributes to explore the molecular mechanisms associated with stress tolerance. Although hosts and stress types eventually determine the mode of action of plant-priming agents, it highlights that many of them act on redox signalling. These include vitamins thiamine, riboflavin and quercetin; organic acids like pipecolic, azelaic and hexanoic; volatile organic compounds such as methyl jasmonate; cell wall components like chitosans and oligogalacturonides; H2O2, etc. This review provides data on how priming inducers promote stronger and faster responses to stress by modulating the oxidative environment, and interacting with signalling pathways mediated by salycilic acid, jasmonic acid and ethylene. The histone modifications involved in priming that affect the transcription of defence-related genes are also discussed. Despite the evolutionary distance between plants and animals, and the fact that the plant innate immunity takes place in each plant cell, they show many similarities in the molecular mechanisms that underlie pathogen perception and further signalling to activate defence responses. This review highlights the similarities between priming through redox signalling in plants and in mammalian cells. The strategies used by pathogens to manipulate the host´s recognition and the further activation of defences also show similarities in both kingdoms. Moreover, phytochemicals like sulforaphane and 12-oxo-phytodienoic acid prime both plant and mammalian responses by activating redox-sensitive genes. Hence research data into the priming of plant defences can provide additional information and a new viewpoint for priming mammalian defence, and vice versa.
... AA and pABA are the plant benzoic acid that is important as the precursor of essential compound in plant. Song et al. [19] reported that pABA was capable to induce resistance against Cucumber mosaic virus and axonopodis. We presumed AA an the capacity to induce SAR in Eksotika and IR grown under green house conditions few days after being infected by PRSV supported by the chemical profiling of ...
... pABA that is important for the synthesis of folic acid, an irreplaceable vitamin B group component has been reported to activate the synthesis of interferon, which has an important antiviral effect ABA are the plant benzoic acid that is important as the precursor of essential compound in plant. Song et al. [19] reported that ABA was capable to induce resistance against Cucumber mosaic virus and Xanthomonas . We presumed AA and pABA have the capacity to induce SAR in Eksotika and IR grown under green house conditions few days after being infected by PRSV-P. ...
Article
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Aims: To Screen for PRSV-P resistance in Carica papaya and interspecific hybrid of Vasconcellea (IR) and to determine the secondary metabolites difference between PRSV-P resistant and susceptible papaya using LCMS-QTOF. Study Design: The experiment was carried out using completely randomized design (CRD). Place and Duration of Study: MARDI Headquarters, Persiaran MARDI-UPM, Original Research Article Haireen et al.; AJBGE, 2(4): 1-11, 2019; Article no.AJBGE.54861 2 Methodology: C. papaya lines L33, L90, L13 and Eksotika were germinated from seed whilst IR was imported in tissue culture from Griffith University Australia. Screening for PRSV-P resistance was carried out using completely randomized design in the glasshouse of Agrobiodiversity and Environment Research Centre, MARDI. Percentage of disease incidence and disease severity of inoculated papaya plant were evaluated weekly for eight weeks. The generated data of disease incidence and disease score were then statistically analysed using SAS 9.4 software. Secondary metabolites analysis of Carica papaya and interspecific hybrid of Vasconcellea (IR) was carried out using LCMS-QTOF in phytochemical laboratory MARDI. The accurate mass compound in the MassHunter Qualitative analysis was confirmed by hits from existing databases [Metlin-Scripps, PCDL (MassHunter Personal Compound Database and Library-Agilent Technologies)]. Results: Screening for PRSV-P resistance amongst Malaysian local lines showed a significant difference (Alpha=0.05) between line L90 [disease incidence (55%); disease score (1.2)] and the PRSV-P susceptible (Eksotika) over eight weeks observation. IR that was also significantly difference to Eksotika categorized as PRSV-P resistance. In order to profile the defense-related secondary metabolites before and after PRSV-P entry in plant, C. papaya (Eksotika) and IR were used to represent PRSV-P susceptible and PRSV-P resistant respectively. IR was used to develop partial resistance to PRSV-P in C. papaya via introgression of resistance genes in other study. Analysis of secondary metabolites using LCMS-QTOF detected anthranilic acid (AA) and para-aminobenzoic acid (pABA) in C. papaya (Eksotika) and IR at day five after inoculation. Interestingly, ϒ-aminobutyric acid (GABA) was only found in IR at rt, 1.881 min based on their accurate mass using LCMS-QTOF prior to PRSV-P inoculation. Conclusion: Findings of this study recommended the usage of L90 in future conventional breeding with other local PRSV-P susceptible varieties such as Eksotika that has better taste and market. ϒ-aminobutyric acid (GABA) that was only found in IR was presumed to be involved in the plant defense response to PRSV-P. It potential to be developed as a resistance chemical marker could be explored in the near future.
... Paraaminobenzoic acid, another member of the vitamin B group, was able to enhance resistance against the cucumber mosaic virus and Xanthomonas axonopodis by inducing systemic acquired resistance (SAR). In the same study, benzothiadiazole was also shown to reduce disease severity, but it also caused adverse effects on the plant, as shoot lengths were shortened and cucumber fruit lengths were significantly reduced, compared with plants treated with para-aminobenzoic acid or untreated control plants [12]. Chitosan, a deacetylated derivative of chitin, can enhance plant defenses by various mechanisms, including scavenging reactive oxygen species (ROS), upregulating antioxidant activities, and activating the octadecanoid pathway that leads to the production of phytoprotective fatty acids [13]. ...
... Para-aminobenzoic acid, another member of the vitamin B group, was able to enhance resistance against the cucumber mosaic virus and Xanthomonas axonopodis by inducing systemic acquired resistance (SAR). In the same study, benzothiadiazole was also shown to reduce disease severity, but it also caused adverse effects on the plant, as shoot lengths were shortened and cucumber fruit lengths were significantly reduced, compared with plants treated with paraaminobenzoic acid or untreated control plants [12]. Chitosan, a deacetylated derivative of chitin, can enhance plant defenses by various mechanisms, including scavenging reactive oxygen species (ROS), upregulating antioxidant activities, and activating the octadecanoid pathway that leads to the production of phytoprotective fatty acids [13]. ...
Article
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Plants are continuously exposed to a wide range of pathogens, including fungi, bacteria, nematodes, and viruses; therefore, survival under these conditions requires a sophisticated defense system. The activation of defense responses and related signals in plants is regulated mainly by the hormones salicylic acid, jasmonic acid, and ethylene. Resistance to pathogen infection can be induced in plants by various biotic and abiotic agents. For many years, the use of abiotic plant resistance inducers has been considered in integrated disease management programs. Recently, natural inducer compounds, such as alginates, have become a focus of interest due to their environmentally friendly nature and their ability to stimulate plant defense mechanisms and enhance growth. Polysaccharides and the oligosaccharides derived from them are examples of eco-compatible compounds that can enhance plant growth while also inducing plant resistance against pathogens and triggering the expression of the salicylic acid-dependent defense pathway.
... Systemic HR SAR SAR [63] [47] Eudesmanolides TMV Tobacco Systemic SAR [64] Eugenol TYLCV Tomato Systemic SAR [65] Harpin (PopW) TMV Tobacco HR SAR, ISR [51] Lactoferrin TMV TYLCV Tobacco Tomato HR Systemic SAR ND [66] [67] Laminarin (sulfated) TMV Tobacco HR SAR/ET [45] Lentinan TMV Tobacco HR SAR? [68] Ningnanmycin TMV Tobacco Systemic SAR, ISR [69] p-aminobenzoic acid (PABA) CMV Capsicum Systemic SAR [70] PeaT1 TMV Tobacco HR SAR [52] 3-pentanol CMV Capsicum Systemic SAR, ISR [71] Probenazole (& saccharin) TMV Tobacco HR SAR [72] Quassinoids PepMoV TMV Capsicum Tobacco Systemic Systemic ND ND [73] [74] Silicon (orthosilicic acid) TMV, TRSV Tobacco Systemic ND [75] Spermine (polyamines) CMV Arabidopsis Systemic ND [76] Strobilurin (fungicide) TMV Tobacco HR SAR [77] Tiadinil TMV Tobacco HR SAR [78] PGPR: Bacillus amyloliquefaciens BBWV, CMV, PepMoV Capsicum Systemic ISR [79] PGPR: Bacillus pumilus CMV Arabidopsis Systemic ISR [24] PGPR: Pseudomonas fluorescens CMV Tobacco Systemic ISR? [80] PGPR: Serattia marcescens CMV Arabidopsis Systemic ISR [24] Penicillium simplicissimum CMV Tobacco Systemic ISR [81] Trichoderma harzianum CMV Tomato Systemic SAR/ISR [82] a Viruses: alfalfa mosaic virus (AMV), broad bean wilt virus (BBMV), cucumber chlorotic yellows virus (CCYV), cucumber mosaic virus (CMV), peanut stunt virus (PSV), pepper mottle virus (PepMoV), southern rice black-streaked dwarf virus (SRBSDV), tobacco mosaic virus (TMV), tobacco necrosis virus (TNV), tobacco ringspot virus (TRSV), tomato bushy stunt virus (TBSV), tomato spotted wilt virus (TSWV), and tomato yellow leaf curl virus (TYLCV). b Other abbreviations: ABA = abscisic acid-mediated resistance; BDR = brassinosteroid-mediated disease resistance; ET = ethylene-mediated resistance; HR = hypersensitive response; ISR = induced systemic resistance; ND = not determined; SAR = systemic acquired resistance. ...
Article
Induced resistance against plant viruses has been studied for many years. However, with the exception of RNA silencing, induced resistance to viruses remains mechanistically less well understood than for other plant pathogens. In contrast, the induction processes involved in induced resistance, comprising basal resistance signaling, effector-triggered immunity, and phytohormone pathways, have been increasingly well characterized in recent years. This has allowed induced resistance to viruses to be placed in a broader conceptual framework linking it to other defense systems, which we discuss in this review. We also discuss the range of agents, including chemicals and beneficial microorganisms and application methods that can be used to induce resistance to viruses.
... Para-aminobenzoic acid (PABA) is a cyclic amino acid belonging to the vitamin B group. Field experiments have proven that it is capable of enhancing resistance against Cucumber mosaic virus and Xanthomonas axonopodis by inducing SAR, while simultaneously improving plant yield (Song et al., 2013). This contrasts with BTH which, in the same study, reduced disease severity, but produced shoot length shortening and significant fruit weight reduction when compared to PABA and control treatments. ...
Article
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Some alternative control strategies of currently emerging plant diseases are based on the use of resistance inducers. This review highlights the recent advances made in the characterization of natural compounds that induce resistance by a priming mechanism. These include vitamins, chitosans, oligogalacturonides, volatile organic compounds, azelaic and pipecolic acid, among others. Overall, other than providing novel disease control strategies that meet environmental regulations, natural priming agents are valuable tools to help unravel the complex mechanisms underlying the induced resistance (IR) phenomenon. The data presented in this review reflect the novel contributions made from studying these natural plant inducers, with special emphasis placed on hexanoic acid (Hx), proposed herein as a model tool for this research field. Hx is a potent natural priming agent of proven efficiency in a wide range of host plants and pathogens. It can early activate broad-spectrum defenses by inducing callose deposition and the salicylic acid (SA) and jasmonic acid (JA) pathways. Later it can prime pathogen-specific responses according to the pathogen's lifestyle. Interestingly, Hx primes redox-related genes to produce an anti-oxidant protective effect, which might be critical for limiting the infection of necrotrophs. Our Hx-IR findings also strongly suggest that it is an attractive tool for the molecular characterization of the plant alarmed state, with the added advantage of it being a natural compound.
... Para-aminobenzoic acid (PABA), a cyclic amino acid belonging to the vitamin B group, is synthesised by bacteria, yeast and plants [81]. Song et al. [82] demonstrated that PABA-mediated systemic acquired resistance protected pepper seedlings against infection by bacterial leaf spot pathogens. PABA secreted by the rhizobacterium Lysobacter antibioticus OH13 showed a broad spectrum of antifungal activities based on its effect on the fungal cell cycle of the bitter rot disease pathogen Colletotrichum fructicola in pears [83,84]. ...
Article
A group of isolates of the genus Luteimonas was characterised, which represented a specific component of the healthy core microbiome of Fraxinus excelsior in forest districts with a high infection rate of H. fraxineus, the causal agent of ash dieback. Based on phylogenomic and phenotypic analyses, a clear differentiation from related Luteimonas species was shown. Comparisons of the overall genome relatedness indices with the closest phylogenetic neighbours resulted in values below the recommended species cut-off levels. In addition, differences in several physiological and chemotaxonomic traits allowed a clear demarcation from the type strains of closely related species. Conclusively, the strain group was considered to represent a novel species in the genus Luteimonas, for which the name Luteimonas fraxinea sp. nov. is proposed, with strain D4P002T (=DSM 113273T = LMG 32455T) as the type strain. A functional analysis of the genome revealed features particularly associated with attachment, biofilm production and motility, indicating the ability of D4P002T to effectively colonise ash leaves. In nursery trials, ash seedlings inoculated with this strain showed suppression of the pathogen over a period of three years. This effect was accompanied by a significant shift in the bacterial microbiome of the plants. Altogether, the exclusive occurrence in the microbiome of tolerant ash trees, the genetic background and the results of the inoculation experiment suggest that strain D4P002T may suppress the penetration and spreading of H. fraxineus in or on ash leaves via colonisation resistance or trigger a priming effect of plant defences against the pathogen.
... In the last two decades a number of molecular structures from diverse chemical classes and natural products have been reported to induce systemic resistance against virus disease, as summarized in Table 2 [130][131][132][133][134][135][136][137][138][139][140][141][142] and Fig. 4. Unfortunately, the antiviral activity of these compounds has been often assessed with incompatible virus-host combinations causing HR, thus their efficacy against systemic infections is not known. When tested with compatible viruses their effectiveness was usually lower than that of BTH, used as reference compound. ...
... Among them, thiamine (vitamin B1) (Ahn et al., 2007), riboflavin (vitamin B2) and quercetin (Jia et al., 2010) are all capable of inducing resistance by increasing Arabidopsis sensitivity to Pst elicitors. In addition, p-aminobenzoic acid, which belongs to the vitamin B group (Song et al., 2013), and menadione sodium bisulfite, a vitamin K3 derivative (Borges et al., 2009), act as inducers by a priming mechanism. Cell-wall derivatives such as chitosan, a polymeric deacetylated derivative of chitin (El Hadrami et al., 2010), and the pectin-derived oligogalacturonides also enhance plant defenses (Rasul et al., 2012). ...
Article
In this study, using untargeted global metabolomic analysis, we have determined and compared the chemical nature of the metabolites altered during the interaction of tomato plants (cv Ailsa Craig) challenged by Botrytis cinerea and Pseudomonas syringae pv tomato DC3000 (Pst), two pathogens with different invasion mechanisms and lifestyles. We also obtained the metabolome of tomato plants primed by the natural resistance inducer hexanoic acid (Hx) and then infected with these pathogens. By contrasting the metabolomic profiles of infected, primed, and primed and infected plants, we determined not only the processes or components related directly to plant defense responses but also inferred the metabolic mechanisms by which pathogen resistance is primed. The data show that basal and Hx-induced resistance (Hx-IR) to Botrytis and Pst is associated with a marked metabolic reprogramming. This includes significant changes in amino acids (aas), sugars, free fatty acids (FAs) and in the primary and secondary metabolism. The comparison of the metabolic profiles of the interactions led to clear differences and reflected the fact that the chemical responses are highly adapted to specific attackers. The data also point to the involvement in tomato of signaling molecules, including pipecolic (Pip) and azelaic acid (Aza), in response to Pst and, interestingly, to Botrytis. The compound 1-methyltryptophan (1-MT) was identified as being associated with the tomato-Pst and tomato-Botrytis interactions as well as with the Hx-IR. Root application of this Trp-derived metabolite also demonstrated its ability to protect tomato plants against both pathogens. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
... Well characterised chemicals, such as BABA, have been demonstrated to enhance resistance by priming of defence mechanisms in the field and in some cases their action also provided a synergistic effect in combination with the use of pesticides (Cohen, 2002). Importantly, the folate precursor para-aminobenzoic acid (PABA) has been successful in inducing resistance against viruses and citrus canker disease caused by Xanthomonas axonopodis, and its use resulted in an increase in yield (Song et al., 2013). Therefore, the scientific community is embracing the idea of investigating whether priming plants for defence could offer a new strategy for pest and disease control. ...
Article
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Crop plants host a variety of pests and diseases that can ultimately reduce agricultural productivity. Current methods of pest and disease control depend largely on pesticides. However, the use of chemicals alone is increasingly regarded as unsustainable due to the development of resistance and the introduction of stricter European regulation. There is a need, therefore, to reduce their use and to pursue the development of new Integrated Pest (and disease) Management (IPM) strategies. Research that focuses on the role that the plant’s immune system can play against these biological threats provides another potential source for future IPM strategies. Plants have sophisticated ways to defend themselves effectively and some stimuli can augment their innate immune capacity to resist future diseases. This phenomenon is known as priming of defence. Studies, mainly in the model plant Arabidopsis thaliana, have unravelled the molecular and physiological mechanisms of this apparent plant ‘vaccination’. This article describes recent findings and provides the ingredients for the “right formulation” in order to integrate green vaccination as a tool for the second green revolution. This article appeared in Volume 27 No 3 of Outlooks on Pest Management, published by Research Information Ltd, and is made available here with the publisher's permission. Copies of OPM articles are available on the IngentaConnect platform at http://www.ingentaconnect.com/content/resinf/opm Please visit http://www.pestoutlook.com for further information
... The level of enzymatic activity persisted for both thiamin and riboflavin treated plants till the 20 th day of inoculation; this indicates that thiamin and riboflavin mediated induced resistance in C. annuum plants was related with the increase in PO, PPO, and PAL activities. These results come in agreement with those reported by [30,38]. ...
Article
Thiamin (B1) and riboflavin (B2) can act as activators and priming factors of defense mechanisms for Tobacco Mosaic Virus (TMV) infection in Capsicum annuum plants. Effect of exogenous application of each vitamin on C. annuum leaves was demonstrated to induce defense responses and systemic resistance against TMV in the untreated parts of the plant. A range of concentrations was used of both vitamins. 70% of inhibition of TMV for thiamin and 64.1% for riboflavin were achieved, when applied just before virus inoculation. The induction of disease resistance and reduction of virus infectivity in C. annuum leaves were determined by indirect ELISA and local lesion host plant assay. The synergetic effect of both vitamins on TMV disease reduction was studied. To investigate the defensive enzymes responsible for the induction of resistance, the levels of Phenylalanine ammonia-lyase (PAL), Polyphenol Oxidase (PPO), and Peroxidase (POD) were examined by specific enzyme assay for each one, and the accumulation of the enzymes was detected 0 to 20 days after treating with the vitamins. Also, the up-regulation and expression of the defense genes POD, PPO, PAL, and some of the pathogenesis related proteins, PR4, PR9, and PR10 were studied by reverse transcriptase polymerase chain reaction (RT-PCR). Application of vitamins B1, and B2 significantly increased the activities of some of the pathogenesis related enzymes, and genes. The possible correlation between timing of application of elicitors and expression of defensive genes was also studied.
... Salicylic acid is a plant elicitor which helps to increase induced resistance against disease. Basically this elicitor increases disease resistance in plant by boosting enzymatic activity such as phenylalanine ammonia-lyase and β-1, 3-glucanase, phenolic compounds, reactive oxygen substances (ROS), Pathogenesis related (PR) protein, ethylene production, nutrient absorption and accumulation and bio-film inhibition etc. (Song et al., 2013;Wang and Liu, 2012;Vallad and Goodman, 2004, Sing et al., 2003and Thomma et al., 2000. Bacillus is an antagonistic rhizospheric bacterium which reduces disease mostly by antagonism. ...
Article
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The study was conducted at the Molecular Plant Pathology Laboratory, Department of Pathology, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh during 15 November to 15 February, 2015 to investigate the effect of salicylic acid (SA) and Bacillus suspension based formulation on bacterial wilt of tomato. Chemicals are either hazardous for environment or less effective against Ralstonia solanacearum causal agent of bacterial wilt of tomato. The effect of SA and Bacillus subtilis on the severity of bacterial wilt and growth of tomato seedling were evaluated. Result showed that combination of SA and Bacillus recorded best performance compared to control and their sole performance. Plant growth such as plant height, branch per plant, fruit per plant and yield per plant were also enhanced by the combined application of SA and Bacillus subtilis. Collectively, SA and Bacillus subtilis proffer a remedy of an environmentally sustainable approach to increase crop production and enhancement of public health.
... Score presented high efficacy against date palm diseases when tested under in vitro and in vivo conditions (6)(7)17). Pentanol is an active organic compound produced by plants and is a component of insect sex pheromones emitted (20). In Arabidopsis, it was reported that 3-Pentanol can trigger plant systemic resistance against Pseudomonas syringae pv. ...
Article
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Recently, a wide range of symptoms including light yellow lesions gradually turning into brown stripes were noticed on date palm leaves in Iraq. In this context, the aim of this study were to isolate the phytopathogens associated with these symptoms, evaluate their pathogenicity and assess the efficacy of two fungicides (Score and Pentanol) under in vitro and in vivo conditions. Two fungal species (Alternaria sp. and Fusarium sp.) were isolated from the symptomatic leaves of date palm. The results of pathogenicity tested proved the ability of Alternaria sp. inoculated separately or in combination with Fusarium sp. to infect the leaves of date palm trees with disease severity index (DSI) values of 67.33% and 65.99%, respectively. The effect of Score (88.76%) and Pentanol (82.91%) against Alternaria sp. was examined by poisoned food technique, which leads a significant increase in mycelial growth inhibition (for 300% of commercial recommended dose of fungicide). Test results indicate that prophylactic spraying of date palm leaves with Score or Pentanol effectively controlled Alternaria sp. with DSI values of 22.65% and 17.87%, respectively. To control Alternaria sp. in field within integrated pest management strategies, chemical control using Score or Pentanol should be taken in consideration.
... Thus, expression of defense-related genes is induced in rice seeds with elevated folate level (Blancquaert et al., 2013b). Furthermore, application of pABA induced systemic acquired resistance (SAR) against artificially infiltrated Xanthomonas axonopodis and naturally occurring tobacco mosaic virus in pepper seedlings (Song et al., 2013). The importance of folate metabolism in biotic stress resistance was also demonstrated in a study assessing global gene expression patterns in response to the fungal pathogen Fusarium pseudograminearum (Powell et al., 2016). ...
Article
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Folates, also known as B9 vitamins, serve as donors and acceptors in one-carbon (C1) transfer reactions. The latter are involved in synthesis of many important biomolecules, such as amino acids, nucleic acids and vitamin B5. Folates also play a central role in the methyl cycle that provides one-carbon groups for methylation reactions. The important functions fulfilled by folates make them essential in all living organisms. Plants, being able to synthesize folates de novo, serve as an excellent dietary source of folates for animals that lack the respective biosynthetic pathway. Unfortunately, the most important staple crops such as rice, potato and maize are rather poor sources of folates. Insufficient folate consumption is known to cause severe developmental disorders in humans. Two approaches are employed to fight folate deficiency: pharmacological supplementation in the form of folate pills and biofortification of staple crops. As the former approach is considered rather costly for the major part of the world population, biofortification of staple crops is viewed as a decent alternative in the struggle against folate deficiency. Therefore, strategies, challenges and recent progress of folate enhancement in plants will be addressed in this review. Apart from the ever-growing need for the enhancement of nutritional quality of crops, the world population faces climate change catastrophes or environmental stresses, such as elevated temperatures, drought, salinity that severely affect growth and productivity of crops. Due to immense diversity of their biochemical functions, folates take part in virtually every aspect of plant physiology. Any disturbance to the plant folate metabolism leads to severe growth inhibition and, as a consequence, to a lower productivity. Whereas today's knowledge of folate biochemistry can be considered very profound, evidence on the physiological roles of folates in plants only starts to emerge. In the current review we will discuss the implication of folates in various aspects of plant physiology and development.
... vez, los eventos de metilación, que ejercen sus efectos regulatorios, tienen íntima relación con el metabolismo del ácido fólico 15 , lo cual se ha inferido a través de estudios en los que el precursor del folato, el ácido para aminobenzoico (PABA) se ha utilizado como agente inductor de resistencia contra fitopatógenos, como por ejemplo, en el caso de inducción de resistencia adquirida del Capsicum annuum (Pimiento) a la bacteria Xanthomonas axonopodis pv. vesicatoria, luego de la exposición a PABA 16 . El proceso de metilación está relacionado con al metabolismo del ácido fólico, debido a que esta vitamina es la fuente del grupo carbono, utilizado para metilar el DNA 17,18 . ...
Article
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Introducción: Las enterobacterias del genero Erwinia spp producen enfermedades en la papa, un tubérculo de consumo masivo. La regulación de la metilación del DNA puede regular la proliferación de la Erwinia, de tal modo que las concentraciones del ácido fólico, pueden tener un efecto en la capacidad patógena del microorganismo. De otra parte, el ácido fólico previene la aparición de defectos del tubo neural en humanos. Objetivo: Evaluar al ácido fólico como un agente bacteriostático de la Erwinia y que a su vez sea parte de la fortificación de alimentos de consumo masivo como la papa. Materiales y métodos: Se llevó a cabo la caracterización bioquímica de la Erwinia chrysanthemi, se estudió su crecimiento frente a diferentes concentraciones de ácido fólico Resultados: Al aumentar las concentraciones de la vitamina, desde 0,3 µg/L hasta 6,8 µg/L se inhibe el crecimiento bacteriano de la Erwinia chrysanthemi. La vitamina inhibe el crecimiento en cultivo de Erwinia chrysanthemi y actúa como como agente bacteriostático, aspecto es de gran relevancia dado que teóricamente, si la papa estuviera fortificada con el micronutriente, este actuaría contra el agente infeccioso y al mismo tiempo contribuiría al consumo adecuado de la vitamina en la población general.
... tomato and Peronospora parasitica in Arabidopsis, and Tobacco mosaic virus and Alternaria alternate in tobacco (Dong and Beer, 2000;Zhang et al., 2009;Abdel-Monaim, 2011). Folate contributes to plant defense against Pseudomonas syringae (Wittek et al., 2015), Cucumber mosaic virus, and Xanthomonas axonopodis (Song et al., 2013). In contrast, some specific vitamins limit defense reactions in plants. ...
Article
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Vitamins maintain growth and development in humans, animals, and plants. Because plants serve as essential producers of vitamins, increasing the vitamin contents in plants has become a goal of crop breeding worldwide. Here, we begin with a summary of the functions of vitamins. We then review the achievements to date in elucidating the molecular mechanisms underlying how vitamins are synthesized, transported, and regulated in plants. We also stress the exploration of variation in vitamins by the use of forward genetic approaches, such as quantitative trait locus mapping and genome‐wide association studies. Overall, we conclude that exploring the diversity of vitamins could provide new insights into plant metabolism and crop breeding. This article is protected by copyright. All rights reserved.
... Reduction of disease severity may be due to PGPR-mediated ISR, which is a plant defence response to pathogen attack by beneficial micro-organisms Ryu et al. 2007;Sultana et al. 2009). Induced resistance including ISR that is induced by various biotic factors such as non-pathogenic organisms (Bakker et al. 2003;El-Sharkawy et al. 2012), and SAR that is activated by chemicals or plant pathogens (Song et al. 2013) and was first reported as early as 1960 by Ross, who mentioned that plant virus can elicit SAR (Ross 1961) The mechanisms of ISR by PGPR against plant viruses are not clear (Duffy et al. 1996). Previous studies indicated that the mechanisms of PGPR to induce systemic resistance against plant viruses may include production of pathogenesis-related (PR) proteins such as PR-1 and PR-2 (Ryals et al. 1996;Ryu et al. 2004), activation of plant mitochondrial enzymes, alternative oxidase (Murphy et al. 1999), increase of total peroxidase and superoxide dismutase activity in treated plants (Benhamou et al. 1996;Jetiyanon et al. 1997), physiological changes in plants, and increase of salicylic acid in leaves (Maurhofer et al. 1994). ...
Article
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Papaya ringspot virus (PRSV-W) and Tomato chlorotic spot virus (TCSV) are responsible for severe losses in cucurbits and tomato production in south Florida and other regions in the USA. Traditional chemicals are not effective to control these viruses. Using plant growth-promoting rhizobacteria (PGPR) may present an alternative to control these viruses. Results from this study demonstrated that applying mixtures of PGPR strains is more efficient to control PRSV-W and TCSV compared to individual PGPR strain only. The application method significantly affected the efficiency of PGPR to control PRSV-W and TCSV. The highest reduction in disease severity of both PRSV-W and TCSV occurred in case of soil drenching with PGPR, followed by root dipping and seed coating treatments. Application of PGPR mixtures of (IN937a & SE34) or (IN937a &, SE34 & T4) were the most efficient methods to control these viral diseases.
... This modification addresses one of the weaknesses of the artificial system based on nutrient agar. A study identified a bacterial volatile 2,3-butanedione from B. subtilis by in vitro screening and then applied the volatile to cucumber and pepper plants cultivated in an open field and found the plants to be significantly protected from a bacterial pathogen, Pseudomonas syringae, and an insect pest aphid, as compared with untreated plants 41,42 , indicating that the results of in vitro screening did indeed have biological relevance under natural conditions. ...
Article
Airborne chemical signals emitted by bacteria influence the behavior of other bacteria and plants. We present an overview of in vitro methods for evaluating bacterial and plant responses to bacterial volatile compounds (BVCs). Three types of equipment have been used to physically separate the bacterial test strains from either other bacterial strains or plants (in our laboratory we use either Arabidopsis or tobacco plant seedlings): a Petri dish containing two compartments (BI Petri dish); two Petri dishes connected with tubing; and a microtiter-based assay. The optimized procedure for the BI Petri dish system is described in this protocol and can be widely used for elucidation of potential function in interactions between diverse microbes and those plant and chemical volatiles emitted by bacteria that are most likely to mediate bacterial or plant responses to BVCs. We also describe a procedure for metabolome-based BVC profiling via dynamic (i.e., continuous airflow) or static headspace sampling using solidphase microextraction (SPME). Using both these procedures, bacteria–bacteria communications and bacteria–plant interactions mediated by BVCs can be rapidly investigated (within 1–4 weeks).
... However, some elicitors for other induced defense responses such as ISR are not associated with allocation fitness costs. The bacterial volatile compounds (e.g., 2,3-butanediol and acetoin) and their derivatives (e.g., 3-pentanol and 4-aminobenzoic acid) stimulate growth and induced resistance in Arabidopsis thaliana and pepper, but do not incur an allocation fitness cost [26][27][28][29] . In the majority of cases, SAR usually leads immediately to an increase in the expression of defense-related genes, whereas ISR instantly induces gene expression after the plant is exposed to the pathogen. ...
Article
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Seed priming is to expose seeds to specific compounds to enhance seed germination. Few studies of plant immune activation through seed priming have been conducted. Here, we introduce an emerging technology that combines seed priming with elicitation of plant immunity using biologically active compounds. This technology is named ‘seed defense biopriming’ (SDB). We prepared heat-stable metabolites from 1,825 root-associated Bacillus spp. isolated from the rhizosphere in South Korea. These preparations were tested for their ability to induce SDB in cucumber and pepper seeds and trigger plant immunity. SDB with heat-stable metabolites of the selected Bacillus gaemokensis strain PB69 significantly reduced subsequent bacterial diseases under in vitro and field conditions and increased fruit yield. Transcriptional analysis of induced resistance marker genes confirmed the upregulation of salicylic acid, ethylene, and jasmonic acid signaling. Mortality of the insect pest Spodoptera litura increased when larvae fed on SDB-treated cucumber tissues. Analysis of the causative bacterial metabolites identified a leucine-proline cyclodipeptide and a commercially obtained leucine-proline cyclodipeptide induced similar results as treatment with the bacterial preparation. Our results indicate that SDB treatment with the heat-stable bacterial metabolite effectively elicited immunity and controlled disease in seedlings to whole plants, thereby increasing yield even under field conditions.
... Moreover, folic acid receptors that are overexpressed on membranes of rapidly proliferating tumor cells are frequently used for the selective internalization of anticancer drugs (a so called "Trojan horse" strategy) [18]. In plants, PABA is known to trigger a systemic acquired resistance (SAR) against bacterial and viral pathogens [19]. Due to its photosensitivity, PABA has also been proposed as a new fluorescent probe, for the selective measurement of peroxyl radical scavenging (PRS) activity in biological samples [20]. ...
Article
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Background: Exposure to ozone level and ultraviolet (UV) radiation is one of the major concerns in the context of public health. Numerous studies confirmed that abundant free radicals initiate undesired processes, e.g. carcinogenesis, cells degeneration, etc. Therefore, the design of redox-active molecules with novel structures, containing radical quenchers molecules with novel structures, and understanding their chemistry and biology, might be one of the prospective solutions. Methods: We designed a group of peptide dendrimers carrying multiple copies of p-aminobenzoic acid (PABA) and evaluated their molecular antioxidant properties in 1,1’-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) tests. Cytotoxicity against human melanoma and fibroblast cells as well as against primary cerebral granule cells (CGC) alone and challenged by neurotoxic sodium glutamate and production of reactive oxygen species (ROS) in presence of dendrimers were measured. Results: PABA-terminated dendrimers express enhanced radical and radical cation scavenging properties in relation to PABA alone. In cellular tests, the dendrimers at 100 M fully suppress and between 20–100 M reduce proliferation of the human melanoma cell line. In concentration 20 M dendrimers generate small amount of the reactive oxygen species (<25%) but even in their presence human fibroblast and mouse cerebellar granule cells remain intact Moreover, dendrimers at 0.2–20 µM concentration (except one) increased the percentage of viable fibroblasts and CGC cells treated with 100 M glutamate. Conclusions: Designed PABA-functionalized peptide dendrimers might be a potential source of new antioxidants with cationic and neutral radicals scavenging potency and/or new compounds with marked selectivity against human melanoma cell or glutamate-stressed CGC neurons. The scavenging level of dendrimers depends strongly on the chemical structure of dendrimer and the presence of other groups that may be prompted into radical form. The present studies found different biological properties for dendrimers constructed from the same chemical fragments but the differing structure of the dendrimer tree provides once again evidence that the structure of dendrimer can have a significant impact on drug–target interactions.
... Score presented high efficacy against date palm diseases when tested under in vitro and in vivo conditions (6)(7)17). Pentanol is an active organic compound produced by plants and is a component of insect sex pheromones emitted (20). In Arabidopsis, it was reported that 3-Pentanol can trigger plant systemic resistance against Pseudomonas syringae pv. ...
Article
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The objective of this study was to isolate and identify the pathogen cause yellowing and Spotting of the detached leaves of date palm and efficiency of Chemical Pesticides to control Spotting and Yellowing of Palm Tissues. The isolation and identification results showed presence of Fusarium spp. and Alternaria fungus from infected roots of infected palm trees and its major causing agent of diseases. As the study aimed to effect of some chemical pesticides, Score and Pentanol, was studied and the results showed the high effect of the pesticide Score at a concentration of 300% where the incidence decreased to 88.76% as an inhibition of the pathogenic fungus as well as the severity of infection using the pesticide Score to 22.65% compared with the pesticide Pentanol where the severity of infection was reduced to 17.87% Compared to the witness 54.33%
... Score presented high efficacy against date palm diseases when tested under in vitro and in vivo conditions (6)(7)17). Pentanol is an active organic compound produced by plants and is a component of insect sex pheromones emitted (20). In Arabidopsis, it was reported that 3-Pentanol can trigger plant systemic resistance against Pseudomonas syringae pv. ...
Preprint
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The objective of this study was to isolate and identify the pathogen cause yellowing and Spotting of the detached leaves of date palm and efficiency of Chemical Pesticides to control Spotting and Yellowing of Palm Tissues. The isolation and identification results showed presence of Fusarium spp. and Alternaria fungus from infected roots of infected palm trees and its major causing agent of diseases. As the study aimed to effect of some chemical pesticides, Score and Pentanol, was studied and the results showed the high effect of the pesticide Score at a concentration of 300% where the incidence decreased to 88.76% as an inhibition of the pathogenic fungus as well as the severity of infection using the pesticide Score to 22.65% compared with the pesticide
... However the resistance source is not introduced into commercial pepper inbred lines yet and it remains to be detail characterization of gene identification and its functions in pepper cells. Apart from R genes or recessive genes, natural compounds from pathogenic or saprophytic bacteria and fungi or their byproducts have shown potential to control CMV disease without reducing plant growth (Choi et al., 2014;Lee and Ryu, 2016;Song et al., 2013). ...
Article
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Cucumber mosaic virus (CMV), the most prevalent virus in chili pepper (Capsicum annuum L.), negatively affects chili pepper production in South Korea. In this study, foliar spraying with β-glucans obtained from the mycelial walls of the yeast-like fungus Aureobasidium pullulans inhibited CMV infection of chili pepper if applied before virus inoculation. At three concentrations, β-glucans from A. pullulans significantly ameliorated CMV symptoms in treated chili pepper; the effect was greater in plants treated with 0.01% β-glucans than 0.005% or 0.001% β-glucans. Double antibody sandwich enzyme-linked immunosorbent assay showed that these β-glucans treatments resulted in 1.7- to 10-fold reductions in CMV accumulation in the treated chili pepper. The glucans did not act directly on the virus and did not interfere with virus disassembly or replication. Foliar spraying with 0.01% β-glucans from A. pullulans at 24 hr intervals for 3 days significantly increased plant height, the total number of fruit, and the fresh weight of chili pepper fruit. However, the stem diameter of chili pepper treated with β-glucans did not increase significantly. These results indicate that foliar spraying with β-glucans from A. pullulans acts an antiviral agent against CMV infection and stimulates chili pepper growth.
... Algae also secrete vitamins, which promote plant growth and plant immunity (Havaux et al., 2009;Goyer, 2010) (Figure 3). Previously studies show that bacteria-derived vitamins B1, B2, and K3, act as elicitors of plant immunity against pathogenic fungi, bacteria, and viruses, and that biotin, thiamine, cobalamin, pantothenic acid, and niacin produced by bacteria enhance plant growth (Strzelczyk et al., 1991;Ahn et al., 2005;Taheri and Hofte, 2007;Liu et al., 2010;Taheri and Tarighi, 2010;Song et al., 2013). Cyanobacteria such as Spirulina, Anabaena, Microcystis, Nostoc, Phormidium, Oscillatoria, Chroococcus, and eukaryotic algae such as Euglrena, also produce thiamine (vitamin B1), riboflavin (vitamin B2), folic acid, ascorbic acid, nicotinic acid (vitamin B3), cyanocobalamin (vitamin B12), and vitamin E (Robbins et al., 1951;Koptera, 1970;Aaronson et al., 1977;Shah and Vaidya, 1977;Gupta et al., 2013). ...
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Previously, algae were recognized as small prokaryotic and eukaryotic organisms found only in aquatic habitats. However, according to a recent paradigm shift, algae are considered ubiquitous organisms, occurring in plant tissues as well as in soil. Accumulating evidence suggests that algae represent a member of the plant microbiome. New results indicate that plants respond to algae and activate related downstream signaling pathways. Application of algae has beneficial effects on plant health, such as plant growth promotion and disease control. Although accumulating evidence suggests that secreted compounds and cell wall components of algae induce physiological and structural changes in plants that protect against biotic and abiotic stresses, knowledge of the underlying mechanisms and algal determinants is limited. In this review, we discuss recent studies on this topic, and highlight the bioprotectant and biostimulant roles of algae as a new member of the plant beneficial microbiome for crop improvement.
... Although we cannot exclude direct effects of the compounds on fungal growth, the data argue in favour of SA-and Fol-induced plant defence mechanisms affecting Bgh propagation in barley. Importantly, Fol-related compounds can promote plant yield [36], whereas SA causes cell death when applied at high concentrations. Thus, although adverse effects on barley susceptibility to hemi-biotrophic bacteria such as Xtc should be considered, Fol could be used as an alternative to SA or BTH to enhance the resistance of barley to the economically relevant powdery mildew pathogen Bgh. ...
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Plants are exposed to numerous pathogens and fend off many of these with different phytohormone signalling pathways. Much is known about defence signalling in the dicotyledonous model plant Arabidopsisthaliana, but it is unclear to which extent knowledge from model systems can be transferred to monocotyledonous plants, including cereal crops. Here, we investigated the defence-inducing potential of Arabidopsis resistance-inducing compounds in the cereal crop barley. Salicylic acid (SA), folic acid (Fol), and azelaic acid (AzA), each inducing defence against (hemi-)biotrophic pathogens in Arabidopsis, were applied to barley leaves and the treated and systemic leaves were subsequently inoculated with Xanthomonastranslucens pv. cerealis (Xtc), Blumeria graminis f. sp. hordei (powdery mildew, Bgh), or Pyrenophora teres. Fol and SA reduced Bgh propagation locally and/or systemically, whereas Fol enhanced Xtc growth in barley. AzA reduced Bgh propagation systemically and enhanced Xtc growth locally. Neither SA, Fol, nor AzA influenced lesion sizes caused by the necrotrophic fungus P. teres, suggesting that the tested compounds exclusively affected growth of (hemi-)biotrophic pathogens in barley. In addition to SA, Fol and AzA might thus act as resistance-inducing compounds in barley against Bgh, although adverse effects on the growth of pathogenic bacteria, such as Xtc, are possible.
... Two PGPR mixtures applied in tomato successfully protected tomato plants against CMV (Murphy et al., 2003) and enhance control of multiple cucumber pathogens (Raupach & Kloepper, 1998). More recently, drench application of pepper plants with bacterial volatile compounds and their derivatives resulted in attenuated symptom development and virus accumulation caused by CMV (Choi et al., 2014;Song et al., 2013). In a recent study, foliar applications with leaf-colonizing bacteria Bacillus amyloliquefaciens strain 5B6 isolated from a cherry leaf, protected Nicotiana benthamiana and pepper plants against CMV (Lee & Ryu, 2016). ...
... The increase level of enzymatic activity in treated tomato plants indicate that, induced resistance was related to the increase in POD and phenolic compounds. Similar trend of results described by Song et al., (2013) andPaz Aranega-Bou, (2014). Furthermore, induced resistance in a number of plant-pathogen interactions has been associated with accumulation of phenolic compounds. ...
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Riboflavin (R) as an antioxidant and Humic acid (HA) as a phenolic compound both can act as activators of defense mechanisms against different plant pathogens but no clear answer concerning to viral diseases. Exogenous application of R at (0, 0.5 and 1.0 mM) and HA at (0, 1 and 2 g/L) on tomato plants were conducted to induce systemic resistance against Tobacco mosaic virus (TMV). All possible combination of both inducers was also investigated. Spraying riboflavin (R2) at 1.0 mM individually and HA1+ R2 at (1 g / L & 1.0 mM), HA2+ R2 at (2 g / L &1.0 mM) in combination treatments reduced the symptoms severity. Moreover, the effect on vegetative growth parameters were clearly decreased in the similar treatments compared to the other treatments. These results were serologically confirmed by ELISA test. The activity of peroxidases enzyme and the total of phenolic compounds were significantly increased in inoculated leaf tissues treated with R2, HA1+ R1 and HA1+ R2. There were increases in reactive oxygen species (ROS) as indicated by elevating the histochemical localization of H2O2 using the 3, 3-diaminobenzidine (DAB)-staining technique in the inoculated leaf tissues treated with R2 followed by HA1+ R2 and HA1+ R1. These findings revealed that, foliar spraying with riboflavin as a single treatment or in combination with humic acid can induce plant defense against TMV.
... PABA is a natural substance, chemically similar to sulphonamides, and is essential for the functioning of metabolic processes, even though the human organism is not able to synthesize it (Gaby 2006;Singh et al. 2011). Sometimes, PABA is called vitamin Bx, for which a positive effect of increasing plant resistance has also been described (Song et al. 2013;Boubakri et al. 2016). Although, according to Wong and Orton (2011), it may cause photosensitive reactions in susceptible individuals, or allergies, predominantly upon apical application, PABA is considered a very safe substance in terms of toxicology, which has been demonstrated even in very high concentrations (Chang & Hu 1996;Correa-Basurto et al. 2005). ...
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We tested 38 legislatively recognised substances such as food additives and supplements for antifungal efficacy, with the aim of providing an alternative to synthetic conventional fungicides. These compounds were tested against 9 significant pathogenic fungal species belonging to the significant genera Fusarium, Penicillium, and Aspergillus. Of these compounds, 6 are proposed as potential candidates to provide a complementary alternative to conventional fungicides. Natamycin provided extreme efficacy expressed as MIC<sub>50</sub> (5–31 μg/ml), followed by BHA and then BHT, CaNa2EDTA, PABA, and chitosan expressed as MIC<sub>50</sub> (0.7–1.9 mg/ml). Safety and antifungal activity were discussed in terms of the mode of action and molecular structure, as well as in terms of potential practical use and legislative requirements for the introduction into practice. We presume that food additives and food supplements are definitely a great source of antifungal compounds. In developed areas of the world (e.g. in the EU), they could represent legislatively recognised compounds, so-called basic substances.
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The discovery of environmentally friendly and inexpensive plant growth regulators (PGRs) for agronomically important crops is a necessity and must be considered a priority worldwide. This study provides the synthesis, structure determination and the biological evaluation of two binary organic salts as potential PGRs. New compounds have dual biological activity and are based on natural metabolite p-aminobenzoic acid (pABAH) and different alkanolamines. Studied compounds exhibit hydrogen-bonded 3D supramolecular architectures with different crystal packing due to the formation of one homosynthon and various heterosynthons. The biological profile of new compounds was investigated in laboratory and greenhouse on Solanum lycopersicum L., revealing the efficiency in promoting plant rooting and plant productivity. The results may have a positive impact on agricultural economics, developing new sustainable PGRs for tomatoes.
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Despite the completion of the Arabidopsis genome sequence, for only a relatively low percentage of the encoded proteins experimental evidence concerning their function is available. Plant proteins that harbour a single PLAT (Polycystin, Lipoxygenase, Alpha-toxin and Triacylglycerol lipase) domain and belong to the PLAT-plant-stress protein family are ubiquitously present in monocot and dicots. However, the function of PLAT-plant-stress proteins is still poorly understood. Therefore, we have assessed the function of the uncharacterised Arabidopsis PLAT-plant-stress family members through a combination of functional genetic and physiological approaches. PLAT1 overexpression conferred increased abiotic stress tolerance, including cold, drought and salt stress, while loss-of-function resulted in opposite effects on abiotic stress tolerance. Strikingly, PLAT1 promoted growth under non-stressed conditions. Abiotic stress treatments induced PLAT1 expression and caused expansion of its expression domain. The ABF/ABRE transcription factors, which are positive mediators of abscisic acid signalling, activate PLAT1 promoter activity in transactivation assays and directly bind to the ABRE elements located in this promoter in electrophoretic mobility shift assays. This suggests that PLAT1 represents a novel downstream target of the abscisic acid signalling pathway. Thus, we showed that PLAT1 critically functions as positive regulator of abiotic stress tolerance, but also is involved in regulating plant growth, and thereby assigned a function to this previously uncharacterised PLAT domain protein. The functional data obtained for PLAT1 support that PLAT-plant-stress proteins in general could be promising targets for improving abiotic stress tolerance without yield penalty.
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Angiosperm plants enjoy genetic mechanisms to establish and maintain the epigenetic methyl groups on cytosine residues at CG, CHG and CHH sites (where H = A, T or C) on genomic DNA. These epigenetic modifications are reversible and are erased and reset post-meiosis in gametes and post-fertilization in nascent embryos, at each generation. They control expression of genes for organ development and response to environment. Pathogens, sucking insects, temperature extremes, salinity, heavy metals, water or nutrient deficiency have been observed to cause genome-wide cytosine hypomethylation. The stress-primed DNA hypomethylation and so induced stress tolerant phenotype(s) are transmitted to subsequent generation(s). Like the biotic and abiotic stresses, certain plant metabolites, salicylic acid and β-aminobutyric acid, and DNA hypomethylation-inducing synthetic chemical azacytidine, are known to prime transgenerational systemic acquired stress resistance/tolerance. Genetic deficiency in RNA-dependent DNA methylation pathway, that establishes methylation marks on DNA, confers on the mutant plants pleiotropic phenotypes, including wide tolerance to stresses. Observations of resistance to priming by stress or non-transfer of the acquired adaptive phenotype to all the descendants or some of the descendants in the first and/or second generation progeny are explained. This may be genotype-specific effect or on account of insufficiency in exposure of gametes to stress or endogenous chemical signal(s) based on stress perception. Need for discovery of new chemicals for priming of stress resistance and of crop variety-wise priming procedures to elicit transgenerational stress resistance to produce epigenetically protected seeds is also emphasized.
Chapter
This chapter deals with both naturally derived inducers (biotic inducers) of resistance and agents which mimic the action of these inducers (abiotic inducers). It concentrates on the effects of topical treatment with inducers on disease control under controlled conditions and in the field. Chitin is the main cell wall component of many filamentous fungi and, along with its deacetylated derivative chitosan, has been shown to elicit defence responses in plants, including lignification and phytoalexin production. Marine algae provide a source of numerous elicitors, including ulvans from green seaweeds, agarans and carrageenans from red seaweeds, and alginates, fucans and laminarin from brown seaweeds. The chapter provides an overview of the effects of Benzo(1,2,3)thiadiazole-7-carbothioic acid S-methyl ester (BTH) on a range of different host-pathogen interactions. The use of abiotic elicitors has become a major promising approach for the agricultural application of induced resistance.
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Background Viral diseases cause significant damage to crop yield and quality. While fungi- and bacteria-induced diseases can be controlled by pesticides, no effective approaches are available to control viruses with chemicals as they use the cellular functions of their host for their infection cycle. The conventional method of viral disease control is to use the inherent resistance of plants through breeding. However, the genetic sources of viral resistance are often limited. Recently, genome editing technology enabled the publication of multiple attempts to artificially induce new resistance types by manipulating host factors necessary for viral infection. Main body In this review, we first outline the two major ( R gene-mediated and RNA silencing) viral resistance mechanisms in plants. We also explain the phenomenon of mutations of host factors to function as recessive resistance genes, taking the eIF4E genes as examples. We then focus on a new type of virus resistance that has been repeatedly reported recently due to the widespread use of genome editing technology in plants, facilitating the specific knockdown of host factors. Here, we show that (1) an in-frame mutation of host factors necessary to confer viral resistance, sometimes resulting in resistance to different viruses and that (2) certain host factors exhibit antiviral resistance and viral-supporting (proviral) properties. Conclusion A detailed understanding of the host factor functions would enable the development of strategies for the induction of a new type of viral resistance, taking into account the provision of a broad resistance spectrum and the suppression of the appearance of resistance-breaking strains.
Article
Plant have developed sophisticated defence mechanisms against microbial pathogens. The recent accumulated information allow us to understand the nature of plant immune responses followed by recognition of microbial factors/determinants through cutting-edge genomics and multi-omics techniques. However, the practical approaches to sustain plant health using enhancement of plant immunity is yet to be fully appreciated. Here, we overviewed the general concept and representative examples on the plant immunity. The fungal, bacterial, and viral determinants that was previously reported as the triggers of plant immune responses are introduced and described as the potential protocol of biological control. Specifically, the role of chitin, glucan, lipopolysaccharides/extracellular polysaccharides, microbe/pathogen-associated molecular pattern, antibiotics, mimic-phytohormones, N-acyl homoserine lactone, harpin, vitamins, and volatile organic compounds are considered. We hope that this review stimulates scientific community and farmers to broaden their knowledge on the microbial determinant-based biological control and to apply the technology on the integrated pest management program.
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Nanoscale sulfur was investigated as a multi-functional agricultural amendment to simultaneously enhance crop nutrition and suppress disease damage. Pristine (nS) and stearic acid coated (cS) sulfur nanoparticles were added to soil (0, 100, or 200 mg/L) that was planted with tomato ( Solanum lycopersicum ) and infested with the Fusarium wilt pathogen. Bulk sulfur (bS), ionic sulfate (iS), and healthy controls were included. In two greenhouse experiments, measured endpoints included time-dependent agronomic and photosynthetic parameters, disease severity/suppression, and a range of mechanistic biochemical and molecular endpoints, including the expression of 13 genes related to two S bioassimilation pathways and pathogenesis-response, and tissue-specific metabolomic profiles. The impact of treatment on the rhizosphere bacterial microbiome was also evaluated. Disease reduced tomato biomass by up to 87%, but amendment with nS and cS significantly reduced disease progress by 54 and 56%, respectively, compared to the infested controls. Increased S accumulation was evident in plant roots and leaves, independent of S type. Molecular analysis revealed particle size and coating-specific impacts on the plants. For nS and cS, two-photon microscopy and time-dependent gene expression data revealed a nanoscale specific elemental S bioassimilation pathway within the plant tissues. These findings correlated well with detailed metabolomic profiling of plant tissues at 4, 8, and 16 d, which exhibited increased disease resistance and plant immunity related metabolites with nanoscale treatment. The data also demonstrate a time-sensitive physiological window whereby nanoscale stimulation of plant immunity will be effective. An analysis of the rhizosphere soil bacterial community revealed minimal impacts from S soil treatments. These findings provide significant mechanistic insight into non-metal nanomaterial-based suppression of plant disease, and significantly advance efforts to develop sustainable nano-enabled agricultural strategies to increase food production.
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Para-aminobenzoic acid (PABA) induced resistance against Pseudomonas syringae pv. tomato in Solanum lycopersicum. Fertilizer application was necessary for induced resistance and only two out of eight breeding lines showed PABA-induced resistance. A comparison of gene expression between a PABA-responsive and PABA-non-responsive line showed that either the responsive line had a faster and stronger increase in expression or the responsive line showed increased expression due to PABA. Although PABA affected SA-related gene expression, changes in gene expression were not always directly related to the responsiveness to PABA. The response to PABA by SA, JA and ET-related mutants showed SA dependence. Factors, such as fertilization practices and host genotype, are important considerations in the development of PABA as a disease management product.
Article
Para-aminobenzoic (PABA) is reported to induce resistance against a range of plant pathogens in different crops in a salicylic acid-dependent manner. However, factors affecting its efficacy are not well understood. Foliar PABA applications on tomato seedlings reduced lesion incidence caused by Pseudomonas syringae pv. tomato (Pst) in a dose-dependent manner in distal leaves up to 18 mM under controlled environment conditions, but only three out of six commercial processing tomato cultivars tested showed a response to PABA. Leaves in direct contact with 9 and 18 mM PABA of both PABA-responsive and PABA-nonresponsive cultivars showed phytotoxicity. In a PABA-responsive cultivar, one, two and three PABA applications were equally effective at reducing lesion incidence in distal leaves, but the duration of control only persisted for approximately 7 days. Although PABA application reduced lesion incidence in distal leaves, the Pst population in leaves was unaffected. Lesions on PABA-treated plants were larger than nontreated plants, and thus the proportion of leaf surface area with lesions was unaffected by PABA treatment. In in vitro assays, 18 and 72 mM PABA produced zones of inhibition against Pst 15 and 50% larger than the ethanol control, demonstrating direct antimicrobial effects of PABA. PABA application did not affect symptom development in a mixed infection of Pst or Xanthomonas spp. in one field experiment with a PABA-responsive cultivar. Further research is needed to understand why PABA was unsuccessful in the field before it is to be used as a practical disease management tool for foliar bacterial diseases of tomato.
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Rice bacterial blight and blast are devastating rice diseases in worldwide. Riboflavin, vitamin B2, is an essential nutrient for human health, and is known to be as a growth regulator and as a plant defense activator against pathogens in plants. In this study, we investigated possibility of increasing internal vitamin B contents and inducing resistances against rice diseases by external foliar application of a riboflavin-based formulator called BioDoctor. In planta bioassay indicated that pretreatment of the foliar application of 1,000-fold or 500-fold diluted BioDoctor significantly induced disease resistance against rice blast and bacterial blight. In addition, about four fold higher levels of riboflavin contents were detected in the BioDoctor treated rice grain and stem compared to those of untreated rice. Our results indicated that foliar application of the riboflavin has a great potential to control plant diseases and to enhance internal vitamin contents in rice.
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The p-aminobenzoic acid was applied for the synthesis of substituted 1-phenyl-5-oxopyrrolidine derivatives containing benzimidazole, azole, oxadiazole, triazole, dihydrazone, and dithiosemi�carbazide moieties in the structure. All the obtained compounds were evaluated for their in vitro antimicrobial activity against Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes, Salmonella enteritidis, Escherichia coli, and Pseudomonas aeruginosa by using MIC and MBC assays. This study showed a good bactericidal activity of γ-amino acid and benzimidazoles derivatives. The antimicro�bial activity of the most promising compounds was higher than ampicillin. Furthermore, two benz�imidazoles demonstrated good antimicrobial activity against L. monocytogenes (MIC 15.62 µg/mL) that was four times more potent than ampicillin (MIC 65 µg/mL). Further studies are needed to better understand the mechanism of the antimicrobial activity as well as to generate antimicrobial compounds based on the 1-phenyl-5-oxopyrrolidine scaffold.
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In the present study, new para-aminobenzoic acid (PABA) grafted on the silica-coated magnetic nanoparticles (Fe3O4@SiO2@Pr-PABA) was prepared and its structure was properly confirmed using Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (XRD), vibrating sample magnetometer (VSM), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray detector (EDS), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), N2 adsorption–desorption technique (BET) and atomic force microscopy (AFM). The Fe3O4@SiO2@Pr-PABA nanocomposite was used as a novel, highly efficient and synergistic recoverable organocatalyst for the synthesis of biologically active 2,3-disubstituted-2,3-dihydroquinazolin-4(1H)-one derivatives via on-water and one-pot three-component condensation of isatoic anhydride, aromatic aldehydes and aromatic or aliphatic amines under reflux conditions. Transition metal-free process, the use of a naturally occurring component and environmental-friendly properties of the catalyst as well as solvent, cost-effectiveness, low catalyst loading, convenient work-up and reusability of the catalyst are some of the remarkable advantages of this green protocol. Graphical abstract
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Nanoscale sulfur can be a multifunctional agricultural amendment to enhance crop nutrition and suppress disease. Pristine (nS) and stearic acid coated (cS) sulfur nanoparticles were added to soil planted with tomatoes (Solanum lycopersicum) at 200 mg/L soil and infested with Fusarium oxysporum. Bulk sulfur, ionic sulfate, and healthy controls were included. Orthogonal end points were measured in two greenhouse experiments, including agronomic and photosynthetic parameters, disease severity/suppression, mechanistic biochemical and molecular end points including the time-dependent expression of 13 genes related to two S bioassimilation and pathogenesis-response, and metabolomic profiles. Disease reduced the plant biomass by up to 87%, but nS and cS amendment significantly reduced disease as determined by area-under-the-disease-progress curve by 54 and 56%, respectively. An increase in planta S accumulation was evident, with size-specific translocation ratios suggesting different uptake mechanisms. In vivo two-photon microscopy and time-dependent gene expression revealed a nanoscale-specific elemental S bioassimilation pathway within the plant that is separate from traditional sulfate accumulation. These findings correlate well with time-dependent metabolomic profiling, which exhibited increased disease resistance and plant immunity related metabolites only with nanoscale treatment. The linked gene expression and metabolomics data demonstrate a time-sensitive physiological window where nanoscale stimulation of plant immunity will be effective. These findings provide mechanistic understandings of nonmetal nanomaterial-based suppression of plant disease and significantly advance sustainable nanoenabled agricultural strategies to increase food production.
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The effect of the resistance inducers methyl jasmonate (MeJA), acybenzolar-S-methyl (BTH) and dipotassium hydrogenphosphate (K2HPO4) was tested by seed soaking and by foliar application to determine whether these resistance inducers controlled root rot and vine decline of melon caused by Monosporascus cannonballus. Tests were carried out in pots and under field conditions in a two-year trial. Application of MeJA to melon seed significantly reduced symptoms of melon root rot and vine decline in soil artificially inoculated with M. cannonballus, and seeds treated with BTH and K2HPO4produced plants with a slightly greater resistance to the pathogen. Greenhouse experiments in soil naturally infected with M. cannonballus in 2006 showed that MeJA treatments by seed soaking followed by foliar applications decreased the severity of the disease. In 2007, both MeJA and BTH significantly reduced root rot and vine decline, but K2HPO4 was ineffective. The resistance inducers differentially induced the synthesis of a number of pathogenesis related (PR) protein isoenzymes, markers of induced resistance in the root system. Using MeJA to induce resistance to root rot and vine decline of melon caused by M. cannonballus may provide a practical supplement to an environmentally-friendly disease management when it is combined with appropriate integrated agronomic practices.
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Plant growth-promoting rhizobacteria (PGPR) strains 89B-27 (Pseudomonas fluorescens) and 90-166 (Serratia marcescens), which previously demonstrated induced systemic resistance in cucumber against some fungal and bacterial diseases, were tested for their capacity to protect Cucumis sativus L. cv. Straight 8 from disease development of cucumber mosaic cucumovirus (CMV). Seed treatment with both PGPR strains significantly and consistently reduced mean numbers of symptomatic plants when CMV was inoculated onto cotyledons. Plants treated with PGPR did not develop initial symptoms 14 days after CMV inoculation and remained symptomless throughout the experimental period. In a comprehensive study with cucumber, no viral antigen could be detected by enzyme-linked immunosorbent assay (ELISA) in any asymptomatic PGPR-treated plants; whereas CMV was evident in every leaf of symptomatic plants. The same two PGPR strains were evaluated for effects on CMV symptom development in tomato in three experiments by measuring the disease severity at six observation dates. In all experiments, the area under the disease progress curve (AUDPC) was significantly lower with strain 89B-27 than in the nonbacterized control. The AUDPC with strain 90-166 was also significantly lower than with strain 89B-27. These results suggest that PGPR should be further evaluated for their potential to contribute toward management of viral plant diseases.
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For the past several decades entomologists and plant pathologists have investigated induced responses of plants to herbivores and to diseases independently, largely oblivious to the advances and traditions of the other discipline. Recently, intense interest in the transduction signals that plants employ to mediate induced responses has made it clear that these two kinds of plant reactions share much in common. One aim of this overview and of this volume is to allow these two disciplines to converse and to learn from their similarities and differences. Induced responses to both herbivores and pathogens involve multiple mechanisms that sometimes may be coordinated. Induced resistance to herbivores and pathogens both show a lack of specificity in terms of inducing agents and organisms that are affected by the responses. The transduction pathways that plants use to activate induced responses to many herbivores differ from those that induce responses to many pathogens, although these two pathways clearly interact. Coincident with an improved understanding of the pathways mediating induction have been attempts to artificially induce resistance using chemical elicitors. These techniques will be used more widely in commercial agriculture during the upcoming years. A consideration of induced responses to herbivores and pathogens has led us to develop a list of research priorities and unanswered questions for the future.
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While once considered noise in the background of constitutive resistance, the phenomenon of induced resistance to herbivores and pathogens is now firmly accepted as an integral component of plant defence. As for other forms of adaptive phenotypic plasticity, fitness costs and benefits of induced resistance are presumed to exist and may be realized in numerous ways; with their relative importance depending on when, where, and how induced resistance is deployed. Carefully controlled studies in which induced resistance has been manipulated in the absence of attack have provided some of the best evidence for direct costs of resistance in plants. Similar studies in the presence of attackers have provided evidence for fitness benefits, but fitness benefits of induced resistance have been rarely measured directly, especially in long-lived plants. The growing interest in placing induced resistance in a broader context has revealed many potential ecological costs and benefits that are dependent on the environment, but their fitness effects have been little examined. Induced indirect resistance (that is, resistance mediated by interactions with the third trophic level) has been an increasingly popular topic that comes with a unique set of potential costs and benefits. Further progress in our understanding of induced resistance will benefit from an increased synthesis of the literature from both agronomic and ecological perspectives, the former containing more pathogen-oriented studies in agricultural crops and the latter containing more examples of induced resistance to herbivores in wild plants. Such a melding of information will also better inform applications of induced resistance in agriculture. Review Methodology: We searched for information using CAB Abstracts, Agricola, Biosis, ISI Web of Science 1 and Google Scholar. We used reference sections of articles obtained by these methods to find additional materials.
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Summary1  Although most theories on plant defence assume that costs will result from the production and maintenance of defensive traits, studies on the costs of induced defence against pathogens are comparatively rare.2  We focus on fitness costs resulting from the chemical induction of systemic acquired resistance (SAR), a rather unspecific form of defence, which can be induced by and is effective against a broad spectrum of bacteria, fungi and viruses.3  We used a model system in which we treated wheat plants that were protected against fungi by ‘traditional’ fungicides with BION® (a benzothiadiazole which induces pathogen resistance). Treated plants were therefore compelled to invest in defence without gaining any profit from the induction.4  Treated plants achieved lower biomass than untreated controls, and developed fewer shoots and ears and therefore produced fewer seeds. The effects were most pronounced in plants that suffered from a shortage of nitrogen, and were observed only when pathogen resistance was induced during lateral shoot production. Later treatment revealed no significant effects.5  We discuss whether the differences between treated and control plants can be interpreted as a consequence of allocation costs. Such costs could result from metabolic competition between processes involved in plant growth and the synthesis of defence-related compounds.
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Many plants are defended indirectly by mutualistic animals. In this field study, we investigated the efficacy of indirect antiherbivore defence in symbiotic and non-symbiotic ant-plant associations in three Macaranga species. We tested whether obligate interactions are more effective than facultative ones by comparing ant-free plants, or parts of plants, with untreated controls. All three species gained significant protection from the ants' presence. The efficacy of defence was higher in the obligate associations represented by M. triloba and M. hosei than in the facultative interaction (M. tanarius). After 40 days of ant exclusion, missing leaf area amounted to 1.7% in M. hosei (compared to 0.2% in untreated, ant-defended controls), 2.6% in M. triloba (controls 1.2%) and 4.2% in M. tanarius (controls 3.2%). In a long-term study of M. triloba and M. hosei, ant protection was orders of magnitude higher than in the short-term results. Short-term experiments obviously are unsuited to obtaining a realistic picture of the long-term efficacy of antiherbivore defence. Within 1 year, ant-free plants lost, on average, between 70% (M. hosei) and 80% (M. triloba) of their total leaf area. Both species appear to require their mutualistic ants for survival. Defence via symbiotic ants is obviously a very effective form of antiherbivore protection. Ants are highly mobile and defend preferentially young, vulnerable leaves and shoot tips, and they fulfil several functions which normally have to be provided by different chemical substances. This may be a general benefit of indirect plant defence, which makes use of "animal-specific" traits rather than intrinsic plant properties.
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Methyl jasmonate, the methyl ester of jasmonic acid, is a volatile plant hormone that acts as an important cellular regulator, mediating diverse developmental processes and defense responses. Methyl jasmonate is synthesized by methylation of jasmonic acid; this reaction is catalyzed by jasmonic acid carboxyl methyltransferase (JMT). Although JMT cDNA had previously been described only forArabidopsis thaliana, here we used PCR to isolate it fromCapsicum annuum L The 389-amino-acid sequence deduced for theJMT gene showed 92% identity to that fromA. thaliana. Southern blot analysis revealed thatJMT is present in the genome as two copies. Our preliminary northern blot detected no JMT transcript, but, through RT-PCR and subsequent Southern blot analysis of products using genespecific probes, we found that transcript levels increased after leaf-wounding. Likewise, 10 µM methyl jasmonate inducedJMT gene expression in leaves. Transcription levels began to increase 10 min after wounding, and were maintained for 1 to 4 h. Moreover, expression of theCaJMT andPIN2 genes was increased by both wounding and MeJA applications, but was not enhanced by treatment with H2O2.
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Studies were done to evaluate specific strains of plant growth promoting rhizobacteria (PGPR) for induced resistance against cucumber mosaic cucumovirus(CMV) in tomato. In greenhouse experiments where plants were challenged by mechanical inoculation of CMV, the percentage of symptomatic plants in the most effective PGPR treatments ranged from 32 to 58%,compared with 88 to 98% in the nonbacterized, challenged disease control treatment. Field experiments were conducted in 1996 and 1997 to evaluate 4 PGPR strain treatments based on superior performance in the greenhouse studies. In the 1996field experiment, tomato plants treated with 3 PGPR strains exhibited a significantly lower incidence of CMV infection and significantly higher yields, compared with nonbacterized, CMV-challenged controls. In 1997, the overall percentages of plants infected with CMV in the control and PGPR treatments was higher than in 1996. CMV symptom development was significantly reduced on PGPR-treated plants in 1997compared with the control, but the percentage of infected plants and tomato yields were not significantly different among treatments. These results suggest that PGPR-mediated induced resistance against CMV infection following mechanical inoculation onto tomato can be maintained under field conditions.
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Plants can be induced to switch on defense reactions to a broad range of pathogens as a result of prior exposure to pathogens or to various chemicals or physical stress. Induced resistance is expressed locally, at the site of the infection or systemically, at sites remotely located from the initial infection. Upon recognition of the initial stimulus by the plant, a signal transduction pathway is set in motion, that includes intra and intercellular signals, and results in the activation of defense mechanisms, mostly by expression of new genes. This brief review will focus on some of the recent advances in the understanding of systemic acquired resistance and on the role played by salicylic acid in this process.
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Book
Plant diseases worldwide are responsible for billions of dollars worth of crop losses every year. With less agrochemicals being used and less new fungicides coming on the market due to environmental concerns, more effort is now being put into the use of genetic potential of plants for pathogen resistance and the development of induced or acquired resistance as an environmentally safe means of disease control. This comprehensive book examines in depth the development and exploitation of induced resistance. Chapters review current knowledge of the agents that can elicit induced resistance, genomics, signalling cascades, mechanisms of defence to pests and pathogens and molecular tools. Further chapters consider the topical application of inducers for disease control, microbial induction of pathogen resistance, transgenic approaches, pathogen population biology, trade offs associated with induced resistance and integration of induced resistance in crop protection. The book concludes with a consideration of socio-economic drivers determining the use of induced resistance, and the future of induced resistance in crop protection.
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A group of beneficial plant bacteria has been shown to increase crop growth referring to as plant growth-promoting rhizobacteria (PGPR). PGPR can decrease plant disease directly, through the production of antagonistic compounds, and indirectly, through the elicitation of a plant defense response termed induced systemic resistance (ISR). While the mechanism of PGPR-elicited ISR has been studied extensively in the model plant Arabidopsis, it is less well characterized in crop plants such as pepper. In an effort to better understand the mechanism of ISR in crop plants, we investigated the induction of ISR by Bacillus cereus strain BS107 against Xanthomonas axonopodis pv. vesicatoria in pepper leaves. We focused on the priming effect of B. cereus strain BS107 on plant defense genes as an ISR mechanism. Of ten known pepper defense genes that were previously reported to be involved in pathogen defense signaling, the expression of Capsicum annum pathogenesis-protein 4 and CaPR1 was systemically primed by the application of strain BS107 onto pepper roots confirming by quantitative-reverse transcriptase PCR. Our results provide novel genetic evidence of the priming effect of a rhizobacterium on the expression of pepper defense genes involved in ISR.
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Systemic acquired resistance (SAR) is a form of induced resistance that is activated by pathogens that induce localized necrotic disease lesions or a hypersensitive response. A major characteristic of SAR is the broad spectrum nature of the protection it confers against a wide range of pathogens, although recent studies suggest that the resistance is most effective against biotrophic and hemibiotrophic pathogens and less effective against necrotrophs. SAR is dependent on salicylic acid signaling and is typically associated with systemic expression of pathogenesis-related protein genes and other putative defenses. Once induced, SAR-expressing plants are primed to respond to subsequent pathogen infection by induction of defenses that are localized at the site of attempted pathogen ingress. Finally, SAR typically does not provide full resistance to disease indicating that the practical application of this form of resistance will require the use of other disease management tools. On the basis of these types of observations, it is likely that SAR and other forms of induced resistance are based on the enhanced ability to express basal defenses.
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The effects of riboflavin on defense responses and secondary metabolism in tobacco (Nicotiana tabacum cv. NC89) cell suspensions and the effects of protecting tobacco seedlings against Phytophthora parasitica var. nicotianae and Ralstonia solanacearum were investigated. Defense responses elicited by riboflavin in tobacco cells included an oxidative burst, alkalinization of the extracellular medium, expression of 4 defense-related genes with different kinetics and intensities, and accumulation of 2 total phenolic compounds, scopoletin and lignin. When applied to tobacco plants challenged by P. parasitica and R. solanacearum, riboflavin treatment resulted in 47.9% and 48.0% protection, respectively. These results suggest that riboflavin can both induce a series of defense responses and secondary metabolism in cell suspensions and protect tobacco against P. parasitica and R. solanacearum.