Prevalence and Geographic Distribution of Resistance to Crown Rust in Avena sterilis

Wahl, I.

doi:10.1094/phyto-60-746

Cited by 65 publications

(14 citation statements)

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“…Levels of polymorphism for resistance have been correlated with ecological conditions or with pathogen population structure indicative of the amount of heterogeneity in selection pressures (Whal 1970;Burdon et al 1983;Parker 1985;Lawrence and Burdon 1989). In this study, high level of polymorphism for resistance at the RGAP loci in T. dicoccoides has been detected Table 7 Spearman rank correlations (r s ) between genetic indices at each RGAP sites and climatic variables, with regular letters for non-significant and bold letters for significant The narrow genetic basis weakened the resistance of wheat cultivars facing adverse factors, and threatened the further improvement of wheat.…”

Section: Discussionmentioning

confidence: 99%

Resistance gene analog polymorphisms (RGAPs) in wild emmer wheat (Triticum dicoccoides) and their ecological associations

Pei

Wei

Chen

et al. 2008

Genet Resour Crop Evol

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Using the 8 specific primer pairs based on the conserved motifs of plant resistance genes, the plant disease resistance gene analog polymorphisms (RGAPs) in 15 wild emmer wheat (Triticum dicoccoides) populations from Israel had been detected. High genetic variations at the RGAP loci were observed in T. dicoccoides populations. A total of 254 discernible bands were obtained among 115 accessions, and 192 bands (75.6%) were polymorphic. Each genotype had a unique banding profile, and the genetic similarity coefficient ranged from 0.094 to 0.862. In T. dicoccoides, the proportion of polymorphic loci (P), the genetic diversity (He) and Shannon's information index were 0.756, 0.362 and 0.541, respectively. The proportion of polymorphic loci (P) per population averaged 0.732 (range: 0.515-0.932); genetic diversity (He) averaged 0.271 (range: 0.212-0.338); and Shannon's information index averaged 0.404 (range: 0.310-0.493). The coefficients of genetic distance (D) among populations averaged 0.107 (range: 0.043-0.178), and the results of Mantel test (r = 0.168, P = 0.091) showed that the estimates of genetic distance were geographically independent. Neighbor-joining cluster analysis suggested that the genetic relationships of T. dicoccoides populations were associated with their ecogeographic distribution. The hierarchical analysis of molecular variance (AMOVA) and the coefficient of gene differentiation (G ST ) values revealed that most of the variations were presented within populations, although significant differences among populations and regions were also detected. The values of P and Shannon's information index were negatively correlated with the two factors: Tdd (day-night temperature difference) and Ev (mean annual evaporation), whereas they were positively correlated with one water factor: Rn (mean annual rainfall). The correlation matrix between He in the RGAPs and geographic variables contained 20 significant (P \ 0.05) correlations. The present study established that T. dicoccoides in Israel had a considerable amount of genetic variations at RGAP loci at least partly correlated with ecological factors.

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Section: Discussionmentioning

confidence: 99%

Resistance gene analog polymorphisms (RGAPs) in wild emmer wheat (Triticum dicoccoides) and their ecological associations

Pei

Wei

Chen

et al. 2008

Genet Resour Crop Evol

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“…The high percentage of intermediate and highly resistant accessions identified in the present study provides evidence that plant explorations that collect in the center of diversity of pathogens or in locations with high incidence of disease or pathogen diversity are a very efficient approach for the identification of new sources of resistance that can broaden the genetic base for disease resistance in common bean. Previous studies in different plantpathogen systems, including the Hordeum spontaneoum-Erysiphe graminis hordei and the A. sterilis-Puccinia coronata avenae systems, have shown that resistance genes tend to aggregate in populations occurring in areas favorable for disease development (25,26,46).…”

Section: Discussionmentioning

confidence: 99%

“…Samples were stored at -20°C until used for characterization. The virulence characteristics of each urediniospore sample was determined by the disease reaction on the primary leaves of one plant of each line of a set of the new 12 standard common bean rust differentials (46). Each of the differential lines or cultivars contains a different source of common bean rust resistance (Table 3).…”

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confidence: 99%

Uromyces appendiculatus in Honduras: Pathogen Diversity and Host Resistance Screening

2013

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Acevedo, M., Steadman, J. R., and Rosas, J. C. 2013. Uromyces appendiculatus in Honduras: Pathogen diversity and host resistance screening Plant Dis. 97:652-661.Bean rust, caused by the fungus Uromyces appendiculatus, is a major constraint for common bean production worldwide. Virulence of U. appendiculatus collected from wild and cultivated Phaseotus spp. was examined in 28 locations across Honduras. Host accessions representing wild and domesticated Phaseolus spp. collected at the same sampling locations were evaluated for resistance against U. appendiculatus. In total, 91 pathotypes were identified from 385 U. appendiculatus isolates according to their virulence on each of the 12 host differentials. No significant difference in pathogen total virulence, measured as the mean disease score, was found between locations. However, significant differences were found in pathotype virulence among isolates collected from different Phaseolus spp. within a location. Moreover, when locations were compared on the basis of pathotype occurrence and frequency, differences among locations were evident. No two locations had the same pathotype composition. The most common pathotype was virulent on 9 of the 12 differential lines. A high number of resistant accessions were identified in Phaseolus coccineus and P. lunatus. Although most wild P. vulgaris accessions were highly susceptible, rust resistance was observed in P. vulgaris landraces collected from farmer's fields. Thirty-two (52%) of the accessions screened showed intermediate to high levels of resistance and, of those, 16% were P. coccineus accessions. Our findings support the hypothesis that interaction of U. appendiculatus in host populations composed of diverse Phaseolus spp. and genotypes has favored highly diverse and virulent pathotypes, creating a center for virulence diversity of the pathogen in Honduras. The high percentage of interrhediate and highly resistant accessions identified in the present study supports the strategy of collecting plants from the center of diversity of a pathogen or in locations with high incidence of disease and pathogen diversity to maximize the probability of identifying new sources of resistance.Bean rust, caused by the fungus Uromyces appendiculatus, is a major constraint for common bean production around the world. U. appendiculatus epidemics have been most serious in tropical and subtropical areas in the Americas and Africa but severe epidemics have also occurred in temperate climates. A high virulence diversity in U. appendiculatus in many geographic regions has been documented (14,21,23,33,39,40,41,44). Despite the high number of virulence patterns described worldwide, two major pathotype groups can be distinguished in {/. appendiculatus. One of the pathotype groups is virulent on common bean cultivars of Andean origin while the second pathotype group is virulent on common bean cultivars of both the Andean gene pool and the Middle American gene pool (2,23). Based on these results, parallel evolution of host and pathogen has been ...

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“…Although wild relatives of crops have long been known to possess polymorphism in pathogen resistance (Wahl, 1970;Zimmer and Rehder, 1976), work in the 1980's documented that wild plant populations possess extensive natural genetic variation in resistance to their natural pathogens (Burdon, 1980;Burdon and Marshall, 1981;Harry and Clarke, 1987;Parker, 1988). Because pathogens are expected to generate strong selection on plant resistance, these observations implied that there may be general costs or tradeoffs that could constrain resistance evolution and thereby promote the maintenance of genetic variation (Parker, 1988(Parker, , 1990).…”

Section: Ipomoea and The Evolution Of Plant-parasite Interactionsmentioning

confidence: 99%

Morning glory as a powerful model in ecological genomics: tracing adaptation through both natural and artificial selection

et al. 2011

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Many diverse questions in ecology and evolution have been addressed using species belonging to the genus Ipomoea, commonly referred to as the morning glory genus. Ipomoea exhibits a wide range of diversity in floral color, growth form, mating system and tolerance to environmental factors, both within and among species, and as such has been a focal group of many investigations in the last 80 years. In this review, we highlight recent work to which Ipomoea species have contributed-from studies of the mating system, molecular evolution, plant-herbivore and plant-parasite interactions to their impact on and importance to agriculture. Genomic resources for this group are currently under development, and given the breadth of studies and history of this group, combined with an expanding genetics toolkit, we argue that Ipomoea should provide the next model organism for ecological genomics.

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Prevalence and Geographic Distribution of Resistance to Crown Rust in Avena sterilis

Cited by 65 publications

References 2 publications

Resistance gene analog polymorphisms (RGAPs) in wild emmer wheat (Triticum dicoccoides) and their ecological associations

Resistance gene analog polymorphisms (RGAPs) in wild emmer wheat (Triticum dicoccoides) and their ecological associations

Uromyces appendiculatus in Honduras: Pathogen Diversity and Host Resistance Screening

Morning glory as a powerful model in ecological genomics: tracing adaptation through both natural and artificial selection

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