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![Symptoms of ascochyta blight [Ascochyta rabiei] in chickpea. (A) Small lesions on foliage. (B) Severe foliar symptoms. (C) Stem lesion with pycnidia. (D) Stem breakage due to girdling. (E) Lesions with concentric rings of pycnidia on pods. (F) Healthy and infested seeds (left and right panels, respectively); kabuli and desi types (top and bottom panels, respectively). Reproduced from Chongo and Gossen (2003).](profile/Yantai-Gan/publication/248909930/figure/fig1/AS:610997236666368@1522684501178/Symptoms-of-ascochyta-blight-Ascochyta-rabiei-in-chickpea-A-Small-lesions-on.png)
Symptoms of ascochyta blight [Ascochyta rabiei] in chickpea. (A) Small lesions on foliage. (B) Severe foliar symptoms. (C) Stem lesion with pycnidia. (D) Stem breakage due to girdling. (E) Lesions with concentric rings of pycnidia on pods. (F) Healthy and infested seeds (left and right panels, respectively); kabuli and desi types (top and bottom panels, respectively). Reproduced from Chongo and Gossen (2003).
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![Fig. 1. Symptoms of ascochyta blight [Ascochyta rabiei] in chickpea....](profile/Yantai-Gan/publication/248909930/figure/fig1/AS:610997236666368@1522684501178/Symptoms-of-ascochyta-blight-Ascochyta-rabiei-in-chickpea-A-Small-lesions-on_Q320.jpg)
Ascochyta rabiei (teleomorph Didymella rabiei) is a directly penetrating, necrotrophic fungus that infects all aboveground parts of chickpea (Cicer arietinum). During spore germination and infection, germ tubes secrete a mucilaginous substance to facilitate attachment to the host surface, and the invading fungus produces cell-wall-lytic enzymes to...
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Context 1
... fungus Ascochyta rabiei (Pass.) Labrousse (teleomorph Didymella rabiei (Kovachevski) v. Arx), is an important disease of chickpea (Cicer arietinum L.) (Nene and Reddy 1987). The pathogen infects all aboveground parts of the plant during all stages of crop development. The disease symptoms caused by A. rabiei in chickpea are illustrated in Fig. 1. En- vironmental conditions and the genetic background of both the cultivars and the pathogen population in a region are important factors in epidemic development ( Chen et al. 2004;Navas-Cortés et al. 1998;Peever et al. 2004). Appli- cation of fungicide reduces disease severity, but is not al- ways cost-effective ( Reddy et al. 1990). ...
Citations
... This leguminous is devastated by the pathogenic fungus Ascochyta rabiei. Despite the use of various control methods, this pathogen continues to pose a significant threat (Jayakumar et al., 2005). Therefore, we focused on selecting resistant chickpea varieties through callus culture. ...
The contact between host plants and pathogens induces the production of phytoalexins composed of phenols, to resist against the pathogen. The aim of this study is to highlight this phenomenon using in vitro culture, and select resistant genotypes of chickpea (Cicer arietinum). Calluses of Cicer arietinum are exposed to the filtered filtrate (enzymes and toxins) of Ascochyta rabiei to demonstrate the production of phenols in the process of resistance. The calluses are produced from INRA 199 and FLIP 84-92C genotypes, as well as the Twist genotype of C. arietinum. The hormonal balances used are: K1 (3 mg/l 2,4-D and 1 mg/l BAP), K2 (2 mg/l 2,4-D), Ma (2 mg/l 2,4-D and 4 mg/l Kinetin), and M8 (2 mg/l 2,4-D, 4 mg/l NAA, and 1 mg/l Kinetin). The calluses are confronted with the filtered filtrate from isolates H1 and E2 of A. rabiei. Phenol extraction is carried out under reflux, and their quantitative estimation is performed using spectrophotometry. The results of callogenesis are influenced by genotype, organ, and hormonal balance (nature and concentration). Significant callogenesis from all four genotypes is recorded on medium K1. The results related to the interaction between C. arietinum calluses and enzymes and toxins of A. rabiei indicate that the highest quantities of phenols are produced by INRA 199 genotypes.
... Succeeding infiltration, the pathogen advances to have organic associations with the host cell, multiplies its hyphae, and spreads infection all over the host system (Ilarslan and Dolar 2002). In response to pathogen attack, the host produces oxidative pressure as an exertion to destroy or impair the pathogen hyphae (Jayakumar et al. 2005). A. rabiei harbors genes essential to overcome oxidative stress produced by the host all through pathogen invasion. ...
Chickpea (Cicer arietinum) is cultivated in more than 50 countries and is one of the most valued legumes due to its nutritional content. Ascochyta blight (AB) is a major disease that significantly affects crop yield leading to a large gap between demand and production. Approaches for disease management like cultural practices and chemical control either have limited effectiveness or are not ecofriendly. The only available environment-friendly approach to improve crop resistance with complete efficacy is breeding resistant genotypes. The vital prerequisite for sustainable agricultural production is the development of durable host resistance. Owing to the diversity of the pathogen population and prevalence of partial resistance in known sources of resistance, chickpea is susceptible to several races of Ascochyta rabiei. Hence, it is challenging to breed varieties with effective and stable resistance. Recent advances in the genetic and genomic know-hows have provided better understanding of the complex host-pathogen interactions. In addition, several AB-resistant gene(s)/QTL/genomic regions have been identified on various linkage groups. These genomic resources could be precisely utilized in genomic-assisted breeding by the plant breeders to develop and/or transfer AB-resistant genomic regions to elite cultivars.
... Certain phenolics such as chlorogenic acids, coumaric acids, caffeic acids, ferulic acids and protocathuic acids present in the roots of plant play a significant role in conferring FW resistance to chickpea (AICRPC, 2019). Several components like chitinase, β-1,3-glucanase, thaumatin proteins, phytoalexin, total phenolic content, sugars and antifungal peptides play a vital role in building up AB resistance in chickpea (Cho et al., 2004;Jayakumar et al., 2005). Information available on enzymes involvement in chickpea-DRR interaction is scanty (Sharma et al., 2016a). ...
... Certain phenolics such as chlorogenic acids, coumaric acids, caffeic acids, ferulic acids and protocathuic acids present in the roots of plant play a significant role in conferring FW resistance to chickpea (AICRPC, 2019). Several components like chitinase, β-1,3-glucanase, thaumatin proteins, phytoalexin, total phenolic content, sugars and antifungal peptides play a vital role in building up AB resistance in chickpea (Cho et al., 2004;Jayakumar et al., 2005). Information available on enzymes involvement in chickpea-DRR interaction is scanty (Sharma et al., 2016a). ...
Chickpea (Cicer arietinum L.) is an important grain legume at
the global level. Among different biotic stresses, diseases are
the most important factor limiting its production, causing
yield losses up to 100% in severe condition. The major dis-
eases that adversely affect yield of chickpea include Fusarium
wilt, Ascochyta blight and Botrytis gray mold. However, dry
root rot, collar rot, Sclerotinia stem rot, rust, stunt disease and
phyllody have been noted as emerging biotic threats to
chickpea production in many production regions. Identification and incorporation of different morphological
and biochemical traits are required through breeding to
enhance genetic gain for disease resistance. In recent years, remarkable progress has been made in the development of trait-specific breeding lines, genetic and genomic resources
in chickpea. Advances in genomics technologies have
opened up new avenues to introgress genes from secondary and tertiary gene pools for improving disease resistance in chickpea. In this review, we have discussed important diseases, constraints and improvement strategies for enhancing disease resistance in chickpea.
... Previously, cutinase (Tenhaken et al., 1997), xylanase (Bruns, 1999;Jayakumar et al., 2005), and exopolygalacturonase (pectinase) (Tenhaken & Barz, 1991) enzymes have been identified in A. rabiei. It was also reported that A. rabiei secretes solanopyrone A, solanopyrone B, solanopyrone C, cytochalasin D, and a proteinaceous toxin during pathogenesis (Chen & Strange, 1994;Hamid & Strange, 2000;Höhl et al., 1991;Kaur, 1995;Kim et al., 2017;Latif et al., 1993). ...
The necrotrophic fungus Ascochyta rabiei causes Ascochyta blight (AB) disease in chickpea. A. rabiei infects all aerial parts of the plant, which results in severe yield loss. At present, AB disease occurs in most chickpea-growing countries. Globally increased incidences of A. rabiei infection and the emergence of new aggressive isolates directed the interest of researchers toward understanding the evolution of pathogenic determinants in this fungus. In this review, we summarize the molecular and genetic studies of the pathogen along with approaches that are helping in combating the disease. Possible areas of future research are also suggested.
Taxonomy:
kingdom Mycota, phylum Ascomycota, class Dothideomycetes, subclass Coelomycetes, order Pleosporales, family Didymellaceae, genus Ascochyta, species rabiei.
Primary host:
A. rabiei survives primarily on Cicer species.
Disease symptoms:
A. rabiei infects aboveground parts of the plant including leaves, petioles, stems, pods, and seeds. The disease symptoms first appear as watersoaked lesions on the leaves and stems, which turn brown or dark brown. Early symptoms include small circular necrotic lesions visible on the leaves and oval brown lesions on the stem. At later stages of infection, the lesions may girdle the stem and the region above the girdle falls off. The disease severity increases at the reproductive stage and rounded lesions with concentric rings, due to asexual structures called pycnidia, appear on leaves, stems, and pods. The infected pod becomes blighted and often results in shrivelled and infected seeds.
Disease management strategies:
Crop failures may be avoided by judicious practices of integrated disease management based on the use of resistant or tolerant cultivars and growing chickpea in areas where conditions are least favourable for AB disease development. Use of healthy seeds free of A. rabiei, seed treatments with fungicides, and proper destruction of diseased stubbles can also reduce the fungal inoculum load. Crop rotation with nonhost crops is critical for controlling the disease. Planting moderately resistant cultivars and prudent application of fungicides is also a way to combat AB disease. However, the scarcity of AB-resistant accessions and the continuous evolution of the pathogen challenges the disease management process.
Useful websites:
https://www.ndsu.edu/pubweb/pulse-info/resourcespdf/Ascochyta%20blight%20of%20chickpea.pdf https://saskpulse.com/files/newsletters/180531_ascochyta_in_chickpeas-compressed.pdf http://www.pulseaus.com.au/growing-pulses/bmp/chickpea/ascochyta-blight http://agriculture.vic.gov.au/agriculture/pests-diseases-and-weeds/plant-diseases/grains-pulses-and-cereals/ascochyta-blight-of-chickpea http://www.croppro.com.au/crop_disease_manual/ch05s02.php https://www.northernpulse.com/uploads/resources/722/handout-chickpeaascochyta-nov13-2011.pdf http://oar.icrisat.org/184/1/24_2010_IB_no_82_Host_Plant https://www.crop.bayer.com.au/find-crop-solutions/by-pest/diseases/ascochyta-blight.
... Ascochyta Blight It is one of the most important foliar diseases of chickpea leading to yield losses as high as 100% (Nene and Reddy 1987;Singh 1990) and prevalent in many parts of the world including India. Ascochyta rabiei (causal organism) isolates have been classified based on their levels of virulence (Udupa et al. 1998;Chen et al. 2004;Jayakumar et al. 2005) into either a two-or three-pathotype system (I, II and III). It is speculated that the disease might have spread from its site of origin to distant continents through chickpea germplasm exchanges. ...
Chickpea is the major pulse crop of India, and it accounts for about 45% of the total area and production of pulses grown in the country. Impressive progress has been made in development of cultivars suited to rainfed ecology. This has helped India in expanding chickpea area in central and southern India and compensating the loss in chickpea area that occurred earlier due to expansion of wheat in irrigated areas of northern India. The genetic variability available in the germplasm, particularly in wild species, should be exploited for broadening the genetic base of varieties and introgressing useful traits, such as resistance to insect pests and diseases. The barriers to interspecific hybridization have restricted utilization of several wild species, and, therefore, dedicated efforts are needed to access genes from these species. High-throughput precision phenotyping protocols need to be developed and used for screening of germplasm and breeding materials for different traits related to stress tolerance and nutritional quality. Rapid advancements in development of chickpea genomic resources during the past decade have made it possible to initiate genomics-assisted breeding in chickpea improvement. Molecular markers associated with several useful traits have been identified. Some of these markers have been validated and are being used in the breeding programmes. Efforts should be made on increasing the number of validated/diagnostic markers, so that genomics-assisted breeding becomes an integrated approach in chickpea breeding programmes. Marker-assisted selection can accelerate breeding process and facilitate combining different desired traits. Integration of these approaches would be important for improving precision and efficiency of chickpea breeding programmes. In this paper, we have reviewed the status of current research efforts and advancements in Indian and future research priorities to tackle newer challenges.KeywordsBreedingChickpeaGenetic improvementImproved varietiesResearch strategies
... Complete resistance or high level of resistance to D. rabiei has not been found in chickpea cultivars so far, and the resistance shown by many cultivars is either partial or incomplete (Jayakumar et al., 2005). Some studies support the idea of oligogenic inheritance, where resistance is conferred by one or two genes (Bhardwaj et al., 2010), while others support the idea that AB resistance is conferred by polygenic inheritance, and several quantitative trait loci (QTLs) have been identified in different mapping populations (Sabbavarapu et al., 2013;Stephens et al., 2014;Garg et al., 2018;Kushwah et al., 2021). ...
Ascochyta blight (AB), caused by the fungal pathogen Ascochyta rabiei, is a devastating foliar disease of chickpea (Cicer arietinum L.). The genotyping-by-sequencing (GBS)-based approach was deployed for mapping QTLs associated with AB resistance in chickpea in two recombinant inbred line populations derived from two crosses (AB3279 derived from ILC 1929 × ILC 3279 and AB482 derived from ILC 1929 × ILC 482) and tested in six different environments. Twenty-one different genomic regions linked to AB resistance were identified in regions CalG02 and CalG04 in both populations AB3279 and AB482. These regions contain 1,118 SNPs significantly associated with AB resistance (p ≤ 0.001), which explained 11.2–39.3% of the phenotypic variation (PVE). Nine of the AB resistance-associated genomic regions were newly detected in this study, while twelve regions were known from previous AB studies. The proposed physical map narrows down AB resistance to consistent genomic regions identified across different environments. Gene ontology (GO) assigned these QTLs to 319 genes, many of which were associated with stress and disease resistance, and with most important genes belonging to resistance gene families such as leucine-rich repeat (LRR) and transcription factor families. Our results indicate that the flowering-associated gene GIGANTEA is a possible key factor in AB resistance in chickpea. The results have identified AB resistance-associated regions on the physical genetic map of chickpea and allowed for the identification of associated markers that will help in breeding of AB-resistant varieties.
... Therefore, to diversify the genetic basis of resistance to AB and to promote resistance durability by gene pyramidization in breeding programs more sources of resistance in chickpea genetic stocks are required. Although resistant varieties have been used to fight the disease since the early 1960s, lack of complete information on the genetic diversity of fungal isolates has always hampered breeding programs so that the resistance of breeding varieties has been broken after sometimes (Jayakumar et al., 2005). Studies have shown that biotic stresses, such as fungi and bacteria, affect plant growth and development. ...
The present study was conducted to identify the genetic sources of resistance of 20 chickpea genotypes in three seedling, Flowering, and podding stages in greenhouse conditions at University of Mohaghegh Ardabili. Disease damage was recorded using a 9-degree scale after observing complete death in the sensitive control genotype. Analysis of variance of the studied traits of chickpea genotypes was conducted via factorial experiment in a completely randomized design at two levels for factor A (disease-free and disease-contaminated conditions) and 18 levels (genotypes) for factor B (Given that the 13 and 15 genotypes were lost due to high susceptibility to disease in the first stage of growth, Samples were taken from 18 genotypes). The results showed that the resistant and susceptible genotypes were more accurately distinguished from each other in the podding stage. At this stage, 9 genotypes with a degree of damage 1, 2, and 3 (less than five) showed high resistance to the causative agent of Ascochyta blight. Physiological and biochemical traits involved in disease resistance were measured. The results showed that all traits except chlorophyll a, chlorophyll b and polyphenol oxidase had significant differences at 1% probability level in terms of disease stress. Chlorophyll a, chlorophyll b and polyphenol oxidase traits were significantly different at 5% probability level. Genotypes were significantly different in terms of chlorophyll a and total chlorophyll traits. In interaction of disease × genotype, only catalase was significantly different among all studied traits. The amount of peroxidase and polyphenol oxidase have been affected by the disease and their rates increased.
... In addition, disruption of the melanin biosynthetic pathway, with regard to the disruption of ArPKS1, in A. rabiei did not alter its virulence towards chickpea [16]. Both these pathogens synthesize DHN and deposit melanin pigment in both pycnidia and pseudothecia fruiting bodies [16,48] but naturally produce unmelanized appressoria [49]. In the case of A. lentis, we did not observe melanin deposition in spores, hyphae or appressoria [50], consistent with its close relative A. rabiei. ...
Sustainable crop production is constantly challenged by the rapid evolution of fungal pathogens equipped with an array of host infection strategies and survival mechanisms. One of the devastating fungal pathogens that infect lentil is the ascomycete Ascochyta lentis which causes black spot or ascochyta blight (AB) on all above ground parts of the plant. In order to explore the mechanisms involved in the pathogenicity of A. lentis, we developed a targeted gene replacement method using Agrobacterium tumefaciens mediated transformation (ATMT) to study and characterize gene function. In this study, we investigated the role of scytalone dehydratase (SCD) in the synthesis of 1,8-dihydroxynaphthalene (DHN)-melanin in AlKewell. Two SCD genes have been identified in AlKewell, AlSCD1 and AlSCD2. Phylogenetic analysis revealed that AlSCD1 clustered with the previously characterized fungal SCDs; thus, AlSCD1 was disrupted using the targeted gene replacement vector, pTAR-hyg-SCD1. The vector was constructed in a single step process using Gibson Assembly, which facilitated an easy and seamless assembly of multiple inserts. The resulting AlKewell scd1::hyg transformants appeared light brown/brownish-pink in contrast to the dark brown pycnidia of the WT strain and ectopic transformant, indicating an altered DHN-melanin production. Disruption of AlSCD1 gene did not result in a change in the virulence profile of AlKewell towards susceptible and resistant lentil varieties. This is the first report of a targeted gene manipulation in A. lentis which serves as a foundation for the functional gene characterization to provide a better understanding of molecular mechanisms involved in pathogen diversity and host specificity.
... (Jayakumar et al., 2005) . (Kimurto et al., 2013) . ...
Background and Objectives
The Fungus causing Ascochyta blight is one of the most important biological factors limiting chickpea cultivation and production in most parts of the world, including Iran.
Materials and Methods
The present study was conducted to evaluating genetic sources of resistance of 20 chickpea genotypes in three seedling, Flowering, and podding stages in greenhouse conditions at University of Mohaghegh Ardabili. Disease damage was recorded using a 9-degree scale after observing complete death in the sensitive control genotype. Analysis of variance of the studied traits of chickpea genotypes was conducted via factorial experiment in a completely randomized design at two levels for factor A (disease-free and disease-contaminated conditions) and 18 levels (genotypes) for factor B (Given that the 13 and 15 genotypes were lost due to high susceptibility to disease in the first stage of growth, Samples were taken from 18 genotypes). Kolmogorov-Smirnov test used to evaluate the normality of data distribution.
Results
The results showed that the resistant and susceptible genotypes were more accurately distinguished from each other in the podding stage. At this stage, 9 genotypes with a degree of damage 1, 2, and 3 (less than five) showed high resistance to the causative agent of Ascochyta blight. Physiological and biochemical traits involved in disease resistance were measured. The results showed that all traits except chlorophyll a, chlorophyll b and polyphenol oxidase had significant differences at 1% probability level in terms of disease stress. Chlorophyll a, chlorophyll b and polyphenol oxidase traits were significantly different at 5% probability level. Genotypes were significantly different in terms of chlorophyll a and total chlorophyll traits. In interaction of disease × genotype, only catalase was significantly different among all studied traits. The amounts of peroxidase and polyphenol oxidase have been affected by the disease and their rates increased. The highest coefficient of variation for Content soluble protein was 74.1 and the lowest for soluble sugar was 16.5. Significant interaction of genotype in stress showed that the trend of genotypes for traits under normal and stress conditions was not the same and superior genotypes under normal conditions were not necessarily recommended for disease stress conditions.
Discussion
A positive relationship between polyphenol oxidase level and pathogen resistance was observed in the plants. The amount of damage that stress inflicts on crops leads to further efforts to understand the effects of disease on different plant mechanisms and requires understanding of appropriate adaptive responses to this environmental factor.
