O. Frenkel

Cornell University, Итак, New York, United States

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Publications (22)81.86 Total impact

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    ABSTRACT: Frenkel, O., Borenstein, M., Shulhani, R., Sharabani, G., Sofer, M., Abu-Moch, F., Lofthouse, M., Manulis-Sasson, S., and Shtienberg, D. 2015 Secondary spread of Clavibacter michiganensis subsp. michiganensis in nurseries and the conditions leading to infection of tomato seedlings. European Journal of Plant Pathology XX:XXX-XXX. Infected seedlings are one of the most important primary sources of inoculum of Clavibacter michiganensis subsp. michiganensis (Cmm), the causal agent of bacterial canker and wilt of tomatoes, in commercial production plots. In this study we tested the hypothesis that a low number of infected source seedlings may give rise to a large number of infected seedlings in the nursery even when careful measures are taken. It was found that the pathogen dispersed spatially from root-inoculated source seedlings and colonized the leaf surfaces of surrounding seedlings to distances of 65–75 cm. A sub-irrigation system reduced, but did not prevent, Cmm dispersal. Infections by epiphytic Cmm populations can occurred under a wide range of temperature conditions, seedling ages and foliar wetness periods. The results emphasize the need to minimize the primary infectious sources as well as developing new strategies to reduce the dispersal during the nursery stage.
    No preview · Article · Oct 2015 · European Journal of Plant Pathology
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    ABSTRACT: We studied the mechanisms of azole resistance in Erysiphe necator by quantifying the sensitivity to myclobutanil (EC50) in 65 isolates from the eastern United States and 12 from Chile. From each isolate, we sequenced the gene for sterol 14-demethylase (CYP51), and measured the expression of CYP51 and homologs of four putative efflux transporter genes, which we identified in the E. necator transcriptome. Sequence variation in CYP51 was relatively low, with sequences of 40 U.S. isolates identical to the reference sequence. Nine U.S. isolates and five from Chile carried a previously identified A to T nucleotide substitution in position 495 (A495T), which results in an amino acid substitution in codon 136 (Y136F) and correlates with high levels of azole resistance. We also found a nucleotide substitution in position 1119 (A1119C) in 15 U.S. isolates, whose mean EC50 value was equivalent to that for the Y136F isolates. Isolates carrying mutation A1119C had significantly greater CYP51 expression, even though A1119C does not affect the CYP51 amino acid sequence. Regression analysis showed no significant effects of the expression of efflux transporter genes on EC50. Both the Y136F mutation in CYP51 and increased CYP51 expression appear responsible for azole resistance in eastern U.S. populations of E. necator.
    No preview · Article · Mar 2015 · Phytopathology
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    ABSTRACT: Severe epidemics of bacterial canker and wilt disease (caused by Clavibacter michiganensis subsp. michiganensis; Cmm) occurred in Israel between the years 2005 to 2007, resulting in substantial yield loss in many greenhouses. As there were no effective means to cope with the disease, a national research project named 'Khosen Clavibacter' ('Khosen' in Hebrew is an acronym for 'Green Agriculture and Clean Environment'), in which all aspects of disease development were studied, was initiated. It was found that the main source of initial inoculum in commercial greenhouses was asymptomatic seedlings provided by the nurseries. The primary source of inoculum in the nurseries was infested seeds. Means to decrease the secondary spread of the pathogen from the primary infected seedling to the adjacent, healthy seedling in the nursery, were developed. In the commercial greenhouses the disease spread spatially during routine production procedures employed by the farm workers. Cmm-contaminated tools spread the disease for only a limited distance (<4 plants) from infected plants. However, touching asymptomatic infected plants bearing guttation droplets prior to touching nearby plants spread the pathogen over longer distances within rows (>22 plants). Experiments to study the effect of plant age at the time of inoculation on disease development revealed that the period during which inoculations led to wilt and death of tomato plants (designated "window of vulnerability") ranged from plants bearing 3-4 leaves (transplanting) to those with 17-18 leaves. Plants inoculated after this period expressed less severe disease symptoms and did not wilt or die. These results suggested that implementation of precautionary measures to avoid touching tomato plants bearing guttation droplets during the window of vulnerability would have a season-long effect on plant mortality and minimize, or even prevent, yield losses. This information was distributed to tomato growers in southern Israel. From August 2010 tomato growers received SMS messages twice a week informing them of the likelihood that weather conditions in the coming days would be conducive to guttation formation. Data collected in commercial greenhouses revealed that implementing the new recommendations resulted in a significant decrease in the occurrence of severe bacterial canker epidemics.
    No preview · Article · Feb 2015 · Acta horticulturae
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    ABSTRACT: Aims Biochar affects the progress of plant diseases caused by soilborne pathogens, frequently featuring U-shaped biochar dose/disease response curves. This study tested this phenomenon in common bean (Phaseolus vulgaris L.) with several biochars. Methods Four biochars prepared from two feedstocks (eucalyptus wood and greenhouse wastes) each at 350 and 600 °C were tested on bean seedling growth and infection caused by Rhizoctonia solani at concentrations of 0–3 % by weight. Biochar direct toxicity to R. solani was quantified in vitro. Results In general, lower concentrations (≤1 %) of biochar suppressed damping-off, whereas higher concentrations (3 %) were ineffective at disease protection. Plant growth in the absence of the pathogen was generally improved at all doses by the four biochars. Maximum growth response (G-Rmax) generally occurred at higher biochar doses than maximum disease reduction (D-Rmax). Direct toxicity to the pathogen could not explain disease reduction. Conclusion Inverted U-shaped biochar dose/plant growth and biochar dose/disease reduction curves are emerging as common patterns in biochar/crop/pathogen systems. Frequently, the inflection between growth promotion and suppression occurs at different doses than the inflection between disease suppression and promotion. We term this the “Shifted Rmax-Effect”. As there is no simple rule-of-thumb for crop/soil/biochar/dose/pathogen combinations, the possible effects of biochar on plant pathogens should not be overlooked.
    Full-text · Article · Nov 2014 · Plant and Soil
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    ABSTRACT: The soil application of biochar, the solid carbon-rich product of biomass pyrolysis, may improve soil quality and crop productivity. Recently, soil applied biochar was found to reduce severity of foliar diseases and soilborne diseases in various crops. Biochar characteristics are expected to affect its disease suppression capability, as there is a profound variability in the physical and chemical properties of biochar depending on the initial feedstock and production parameters. The aim of this research was to explore the influence of biochar produced from different feedstocks and at different production temperatures on its ability to suppress the soilborne pathogen, Rhizoctonia solani, in cucumber (Cucumis sativus L.). Biochar prepared from two feedstocks (Eucalyptus wood (EUC) and Greenhouse waste (GHW)), each produced at 350 and 600 °C were tested for their suppressive ability against damping-off at concentrations of 0–3%. In general, biochar addition at relatively lower concentrations enhanced plant growth performance and suppressed damping-off by R. solani. However, at higher concentrations, biochar was ineffective or even increased the disease incidence and severity as compared with the control, forming a U-shape response curve versus biochar concentration. Biochars produced at both low and high temperatures were equally effective against various disease parameters but suppression of disease was affected by the feedstock type. There was a significant interaction between feedstock and concentration for the final damping-off incidence and other disease parameters, indicating that each feedstock had an optimum concentration for disease control. The most effective dose for suppressing disease was 1% for EUC biochar and 0.5% for GHW biochar. In conclusion, R. solani suppression in cucumber induced by biochar soil amendment is feedstock and concentration dependent.
    Full-text · Article · Nov 2014
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    ABSTRACT: Clavibacter michiganensis subsp. michiganensis (Cmm), the causal agent of bacterial canker and wilt, causes severe economic losses in tomato nethouses and greenhouses worldwide. Seedlings which were transplanted and inoculated monthly during two years of research wilted and died earlier in the spring (21-24°C) and autumn (18-23°C) than in the winter (15-18°C) and summer (28-31°C): T50 (the time taken for 50% of the plants to wilt or die) was 2 and 3–4 months after inoculation, respectively. A highly significant correlation was found between the average temperatures during the first month after inoculation and T50; The shortest T50 mortality (70 days) was observed for an average temperature of 26o C. Expression of virulence genes (pat-1, celA, chpC and ppaA) was higher in plants inoculated in the spring than in those inoculated in the summer. In another set of experiments, seedlings were inoculated and maintained in controlled-environment growth chambers for two weeks. Then they were transplanted and maintained in commercial-type greenhouses for four to five months. The temperatures prevailing on the first 48 hours after inoculation were found to affect Cmm population size and virulence-gene expression and to have season-long effects on bacterial canker development. This article is protected by copyright. All rights reserved.
    No preview · Article · Oct 2014 · Plant Pathology
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    ABSTRACT: The purpose of this review is to examine how biochar additions to soil can affect plant diseases caused by soilborne pathogens, with particular attention to mechanisms and knowledge gaps. Until now, biochar soil amendment has been reported to affect the progress of diseases caused by soilborne plant pathogens in six distinct pathosystems. Disease severity frequently exhibits a U-shaped response curve, with a minimum at some intermediate biochar dose. Alteration of plant disease intensity by biochar added to soil may result from its varied influences on the soil–rhizosphere–pathogen–plant system. These influences may involve myriad biochar properties such as nutrient content, water holding capacity, redox activity, adsorption ability, pH and content of toxic or hormone-like compounds. The direct and indirect impacts of biochar on the soil environment, host plant, pathogen and the rhizosphere microbiome can have domino effects on both plant development and disease progress
    Full-text · Article · Aug 2014 · Carbon Management
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    Max Kolton · Omer Frenkel · Yigal Elad · Eddie Cytryn
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    ABSTRACT: Members of the Flavobacterium genus are often highly abundant in the rhizosphere. Nevertheless, the physiological characteristics associated with their enhanced rhizosphere competence are currently an enigma. Flavobacteria possess a unique gliding-motility mechanism that is tightly associated with a recently characterized Bacteroidetes-specific type IX (T9SS) protein secretion system, which distinguishes them from the rest of the rhizosphere microbiome. We hypothesize that proper functionality of this complex may confer a competitive advantage in the rhizosphere. To test this hypothesis, we constructed mutant and complement root-associated flavobacterial variants with dysfunctional secretion and gliding motility, and tested them in a series of in-planta experiments. These mutants demonstrated significantly lower rhizosphere persistence (approx. 10-fold), plant root colonization (approx. 5-fold) and seed adhesion capacity (approx. 7-fold) than the wild type strains. Furthermore, the biocontrol capacity of the mutant strain towards foliar-applied Clavibacter michiganensis was significantly impaired relative to the wild type strain, suggesting a role of the gliding/secretion complex in plant protection. Collectively these results provide an initial link between the high abundance of flavobacteria in rhizosphere and their unique physiology, indicating that the flavobacterial gliding-motility/secretion complex may play a central role in root colonization and plant defense.
    Full-text · Article · Jun 2014 · Molecular Plant-Microbe Interactions
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    ABSTRACT: The soil application of biochar, the solid carbon-rich product of biomass pyrolysis, may improve soil quality and crop productivity. Recently, soil applied biochar was found to reduce severity of foliar diseases and soilborne diseases in various crops. Biochar characteristics are expected to affect its disease suppression capability, as there is a profound variability in the physical and chemical properties of biochar depending on the initial feedstock and production parameters. The aim of this research was to explore the influence of biochar produced from different feedstocks and at different production temperatures on its ability to suppress the soilborne pathogen, Rhizoctonia solani, in cucumber (Cucumis sativus L.). Biochar prepared from two feedstocks (Eucalyptus wood (EUC) and Greenhouse waste (GHW)), each produced at 350 and 600 °C were tested for their suppressive ability against damping-off at concentrations of 0–3%. In general, biochar addition at relatively lower concentrations enhanced plant growth performance and suppressed damping-off by R. solani. However, at higher concentrations, biochar was ineffective or even increased the disease incidence and severity as compared with the control, forming a U-shape response curve versus biochar concentration. Biochars produced at both low and high temperatures were equally effective against various disease parameters but suppression of disease was affected by the feedstock type. There was a significant interaction between feedstock and concentration for the final damping-off incidence and other disease parameters, indicating that each feedstock had an optimum concentration for disease control. The most effective dose for suppressing disease was 1% for EUC biochar and 0.5% for GHW biochar. In conclusion, R. solani suppression in cucumber induced by biochar soil amendment is feedstock and concentration dependent.
    Full-text · Article · Jan 2014 · Soil Biology and Biochemistry
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    ABSTRACT: Random mating and recombination in heterothallic ascomycetes should result in high genotypic diversity, 1:1 mating-type ratios, and random associations of alleles, or linkage equilibrium, at different loci. To test for random mating in populations of the grape powdery mildew fungus Erysiphe necator, we sampled isolates from vineyards of Vitis vinifera in Burdett, NY (NY09) and Winchester, VA (VA09) at the end of the epidemic in fall 2009. We also sampled isolates from the same Winchester, VA vineyard in spring 2010 at the onset of the next epidemic. Isolates were genotyped for mating type and 11 microsatellite markers. In the spring sample, which originated from ascospore infections, nearly every isolate had a unique genotype. In contrast, fall populations were less diverse. In all, 9 of 45 total genotypes in VA09 were represented by two or more isolates; 3 of 40 total genotypes in NY09 were represented by two or more isolates, with 1 genotype represented by 20 isolates. After clone correction, mating-type ratios in the three populations did not deviate from 1:1. However, even with clone correction, we detected significant linkage disequilibrium (LD) in all populations. Mantel tests detected positive correlations between genetic and physical distances within vineyards. Spatial autocorrelation showed aggregations up to 42 and 3 m in VA09 and NY09, respectively. Spatial autocorrelation most likely results from short dispersal distances. Overall, these results suggest that spatial genetic aggregation and clonal genotypes that arise during the asexual phase of the epidemic contribute to persistent LD even though populations undergo sexual reproduction annually.
    No preview · Article · Jul 2012 · Phytopathology
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    ABSTRACT: Race-specific resistance against powdery mildews is well documented in small grains but, in other crops such as grapevine, controlled analysis of host-pathogen interactions on resistant plants is uncommon. In the current study, we attempted to confirm powdery mildew resistance phenotypes through vineyard, greenhouse, and in vitro inoculations for test cross-mapping populations for two resistance sources: (i) a complex hybrid breeding line, 'Bloodworth 81-107-11', of at least Vitis rotundifolia, V. vinifera, V. berlandieri, V. rupestris, V. labrusca, and V. aestivalis background; and (ii) Vitis hybrid 'Tamiami' of V. aestivalis and V. vinifera origin. Statistical analysis of vineyard resistance data suggested the segregation of two and three race-specific resistance genes from the two sources, respectively. However, in each population, some resistant progeny were susceptible in greenhouse or in vitro screens, which suggested the presence of Erysiphe necator isolates virulent on progeny segregating for one or more resistance genes. Controlled inoculation of resistant and susceptible progeny with a diverse set of E. necator isolates clearly demonstrated the presence of fungal races differentially interacting with race-specific resistance genes, providing proof of race specificity in the grape powdery mildew pathosystem. Consistent with known race-specific resistance mechanisms, both resistance sources were characterized by programmed cell death of host epidermal cells under appressoria, which arrested or slowed hyphal growth; this response was also accompanied by collapse of conidia, germ tubes, appressoria, and secondary hyphae. The observation of prevalent isolates virulent on progeny with multiple race-specific resistance genes before resistance gene deployment has implications for grape breeding strategies. We suggest that grape breeders should characterize the mechanisms of resistance and pyramid multiple resistance genes with different mechanisms for improved durability.
    Full-text · Article · Jan 2012 · Phytopathology
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    ABSTRACT: Ascochyta blight, caused by Didymella rabiei, affects both domesticated chickpea and its congeneric wild relatives. The aim of this study was to compare the aggressiveness of D. rabiei isolates from wild and domesticated Cicer spp. in Turkey and Israel on wild and domesticated hosts from both countries. A total of eight isolates of D. rabiei sampled from C. pinnatifidum, C. judaicum and C. arietinum in Turkey and Israel was tested on two domesticated chickpea cultivars and two wild Cicer accessions from Turkey and Israel. Using cross-inoculation experiments, we compared pathogen aggressiveness across the different pathogen and host origin combinations. Two measures of aggressiveness were used, incubation period and relative area under the disease progress curve. The eight tested isolates infected all of the host plants, but were more aggressive on their original hosts with one exception; Turkish domesticated isolates were less aggressive on their domesticated host in comparison to the aggressiveness of Israeli domesticated isolates on Turkish domesticated chickpea. C. judaicum plants were highly resistant against all of the isolates from different origins except for their own isolates. Regardless of the country of origin, the wild isolates were highly aggressive on domesticated chickpea while the domesticated isolates were less aggressive on the wild hosts compared with the wild isolates. These results suggest that the aggressiveness pattern of D. rabiei on different hosts could have been shaped by adaptation to the distinct ecological niches of wild vs. domesticated chickpea. KeywordsAscochyta blight–Disease severity–Host adaptation–Incubation period–Wild Cicer
    Full-text · Article · Nov 2011 · European Journal of Plant Pathology
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    ABSTRACT: Transcriptome sequences of the grape powdery mildew fungus Erysiphe necator were used to develop microsatellite markers (EST-SSRs) to study its relatively unexplored population structure in its centre of diversity in eastern North America. Screening the transcriptome sequences revealed 116 contigs with candidate microsatellites, from which 11 polymorphic microsatellite markers were developed from 31 markers tested. Eight of these markers were used to genotype isolates from different regions and hosts in the eastern USA and compare them to samples from southern France and Italy. Genetic diversity in the eastern USA is much greater than in Europe. Bayesian cluster analyses showed that 10 isolates from North America have high affinities with, but differ from, European group A; these are referred to as A-like isolates. No isolates with close affinity to European group B were found in the eastern USA. Bayesian analyses also detected genetic differentiation between isolates from Vitis rotundifolia and isolates from other Vitis hosts. Genetic differentiation detected between the northeastern and southeastern USA was mostly attributable to the A-like isolates in the southeast, which are significantly more aggressive than the other populations. This research demonstrates that transcriptome sequencing of fungal pathogens is useful for developing genetic markers in protein-coding regions and highlights the role of these markers in population biology studies of E. necator.
    No preview · Article · Jul 2011 · Plant Pathology
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    ABSTRACT: Powdery mildews are phytopathogens whose growth and reproduction are entirely dependent on living plant cells. The molecular basis of this life-style, obligate biotrophy, remains unknown. We present the genome analysis of barley powdery mildew, Blumeria graminis f.sp. hordei (Blumeria), as well as a comparison with the analysis of two powdery mildews pathogenic on dicotyledonous plants. These genomes display massive retrotransposon proliferation, genome-size expansion, and gene losses. The missing genes encode enzymes of primary and secondary metabolism, carbohydrate-active enzymes, and transporters, probably reflecting their redundancy in an exclusively biotrophic life-style. Among the 248 candidate effectors of pathogenesis identified in the Blumeria genome, very few (less than 10) define a core set conserved in all three mildews, suggesting that most effectors represent species-specific adaptations.
    Full-text · Article · Dec 2010 · Science
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    ABSTRACT: Eastern North America is considered the center of diversity for many Vitis spp. and for the grape powdery mildew pathogen, Erysiphe necator. However, little is known about populations of E. necator from wild Vitis spp. We determined the phenotypic variation in pathogenicity and aggressiveness of E. necator among isolates from wild and domesticated Vitis spp. from diverse geographic regions in the eastern United States. To test pathogenicity, we inoculated 38 E. necator isolates on three wild Vitis spp., two commercially grown hybrids and the European wine grape, Vitis vinifera. V. rotundifolia (muscadine grape) was the only host species on which complete host specialization was evident; it was only susceptible to isolates collected from V. rotundifolia. All isolates, regardless of source host, were pathogenic on the other Vitis spp. We found no differences in components of aggressiveness latent period and lesion size among isolates from different source hosts when inoculated on V. vinifera, which is highly susceptible to powdery mildew. However significant variation was evident among isolates on the more resistant V. labruscana 'Niagara'. Isolates from the wild species V. aestivalis were the most aggressive, whereas isolates from V. vinifera were not more aggressive than isolates from other source hosts. Greater aggressiveness was also detected among isolates from the southeastern United States compared with isolates from the northeastern United States.
    No preview · Article · Nov 2010 · Phytopathology
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    ABSTRACT: Boron is a microelement required for normal growth and development of plants but its positive effect is restricted to a narrow range of concentrations. The gradual increase in use of recycled water, which contains high concentrations of boron for irrigation, has already raised the level of boron in soils and plants in southern Israel. This research was conducted to examine the direct effects of sub-phytotoxic boron concentrations on potato late blight epidemics and to explore the mode of action of boron against Phytophthora infestans. When boron was applied alone to field grown potato plants it did not affect the epidemic. However, together with a reduced rate of the fungicide Melody Duo (propineb + iprovalicarb), boron improved late blight suppression compared to plants treated with the fungicide alone. The ED50 of boron against P. infestans (256·4 mg L−1) was about 6400 times higher than the ED50 value of the fungicide chlorothalonil (0·04 mg L−1), indicating that boron does not have a direct fungicidal activity that would explain the level of protection seen in the field. In greenhouse experiments conducted with potted tomato plants, boron decreased late blight severity in both treated leaves and distant leaves not treated with boron. The results suggest that boron is active locally but also may induce systemic acquired resistance against P. infestans.
    Full-text · Article · Jul 2010 · Plant Pathology
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    ABSTRACT: The Fertile Crescent is the centre of domestication of chickpea (Cicer arietinum) and also the place of origin of its pathogens. Agrosystems provide different environments to natural eco-systems, thus imposing different types of selection on pathogens. Here, the genetic structure and in vitro temperature growth response of the chickpea pathogen Didymella rabiei from domesticated chickpea (59 isolates from Turkey and 31 from Israel) and wild Cicer spp. (three isolates from Turkish C. pinnatifidum and 35 from Israeli C. judaicum) were studied. Six sequence-tagged microsatellite site (STMS) primer pairs were used to determine the genetic structure of the 128 D. rabiei isolates. Turkish isolates exhibited the highest genetic diversity (H = 0·69). Turkish and Israeli D. rabiei from domesticated chickpea were genetically closer to each other than isolates from the wild Cicer spp. Analysis of molecular variance showed that 54% of the genetic variation resided between isolates from wild and domesticated origins. EF1-α sequences distinguished between D. rabiei isolates from domesticated and wild Cicer spp. by four polymorphic sites. Nevertheless, a certain degree of mixing between isolates from wild and domesticated origin was demonstrated using the Bayesian algorithm as well as with principal coordinates analysis. Isolates sampled from domesticated chickpea from both countries were better adapted to temperatures typical of Levantine spring and had a significantly larger colony area at 25°C than at 15°C (typical Levantine winter temperature). These observations were in accordance to the heritability values of the temperature growth response.
    Full-text · Article · May 2010 · Plant Pathology
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    ABSTRACT: For millennia, chickpea (Cicer arietinum) has been grown in the Levant sympatrically with wild Cicer species. Chickpea is traditionally spring-sown, while its wild relatives germinate in the autumn and develop in the winter. It has been hypothesized that the human-directed shift of domesticated chickpea to summer production was an attempt to escape the devastating Ascochyta disease caused by Didymella rabiei. We estimated genetic divergence between D. rabiei isolates sampled from wild Cicer judaicum and domesticated C. arietinum and the potential role of temperature adaptation in this divergence. Neutral genetic markers showed strong differentiation between pathogen samples from the two hosts. Isolates from domesticated chickpea demonstrated increased adaptation to higher temperatures when grown in vitro compared with isolates from the wild host. The distribution of temperature responses among progeny from crosses of isolates from C. judaicum with isolates from C. arietinum was continuous, suggesting polygenic control of this trait. In vivo inoculations of host plants indicated that pathogenic fitness of the native isolates was higher than that of their hybrid progeny. The results indicate that there is a potential for adaptation to higher temperatures; however, the chances for formation of hybrids which are capable of parasitizing both hosts over a broad temperature range are low. We hypothesize that this pathogenic fitness cost is due to breakdown of coadapted gene complexes controlling pathogenic fitness on each host and may be responsible for maintenance of genetic differentiation between the pathogen demes.
    Full-text · Article · Nov 2009 · Applied and Environmental Microbiology
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    O Frenkel · A Sherman · S Abbo · D Shtienberg
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    ABSTRACT: Domesticated chickpea (Cicer arietinum) and its wild relative C. judaicum grow in sympatric distribution in Israel and both are susceptible to Ascochyta blight caused by Didymella rabiei. C. arietinum was grown for millennia in drier and hotter Levantine spring conditions while C. judaicum grows in the wetter and milder winters. Accordingly, it is possible that D. rabiei isolates originated from C. arietinum are adjusted to the less favorable spring conditions. Here, 60 isolates from both origins were tested in vitro for their hyphal growth at 15 and 25 degrees C. Isolates from C. arietinum had a significantly larger colony area at 25 degrees C than at 15 degrees C (P < 0.001) while no such differences were detected between isolates from C. judaicum. D. rabiei isolates from wild and domesticated origins were used to inoculate nine C. judaicum accessions and two domesticated chickpea cultivars and their aggressiveness patterns were determined using five measures. On domesticated chickpea, isolates from domesticated origin were significantly more aggressive in four out of the five aggressiveness measures than isolates from wild origin. On C. judaicum, isolates from wild origin were generally more aggressive than isolates from domesticated origin. The results suggest that the habitat segregation between wild and domesticated Cicer influences the pathogens ecological affinities and their aggressiveness patterns.
    Preview · Article · May 2008 · Phytopathology
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    S. Abbo · O. Frenkel · A. Sherman · D. Shtienberg
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    ABSTRACT: The primary and secondary centres of origin of domesticated plants are often also the places of origin of their pathogens. Therefore, the Near Eastern cradle of agriculture, where crop plants, their wild progenitors, and other con-generic taxa grow sympatrically, may hold some clues on the biology of the pathogens of the respective crops. Unlike the situation in the well-studied Near Eastern cereals and their important diseases, hardly any data are available on basic questions regarding grain legumes. What is the role of genetic diversity at resistance loci of the wild hosts and is it greater compared with the cultigens? Are populations of Ascochyta pathogens infecting wild legumes genetically distinct from populations infecting their domesticated counterparts, and if so, is this differentiation related to differences in host specialization or to adaptation to different ecological conditions? Do isolates originating from wild taxa exhibit a similar level of aggressiveness and have different aggressiveness alleles compared with those originating from domesticated grain legumes? In this review we propose an experimental framework aimed at gaining answers to some of the above questions. The proposed approach includes comparative epidemiology of wild vs. domesticated plant communities, co-evolutionary study of pathogens and their hosts, phenotypic and genetic characterization of fungal isolates from wild and domesticated origins, and genetic analyses of pathogenicity and parasitic fitness among progeny derived from crosses between isolates from wild and domesticated hosts.
    Full-text · Chapter · Sep 2007

Publication Stats

417 Citations
81.86 Total Impact Points

Institutions

  • 2010-2015
    • Cornell University
      • Department of Plant Pathology and Plant-Microbe Biology
      Итак, New York, United States
  • 2010-2014
    • Agricultural Research Organization ARO
      • Department of Plant Pathology and Weed Research
      Beit Dajan, Central District, Israel
  • 2005-2011
    • Hebrew University of Jerusalem
      • Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture
      Yerushalayim, Jerusalem District, Israel