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1.
Virulence on a standard set of 12 common bean differential varieties, DNA sequence of repetitive-elements (Rep-PCR) and random amplified microsatellites (RAMS) were used to assess the genetic variability of 200 Colletotrichum lindemuthianum isolates collected from Andean and Mesoamerican bean varieties and regions. High levels of pathotypic (90 pathotypes) and genetic diversity (0.97) were identified among 200 isolates, revealing that C. lindemuthianum is a highly diverse pathogen. Although a significant number of pathotypes were common to Andean and Mesoamerican regions, many more were only found in the Mesoamerican region. Cluster analysis of virulence and molecular data did not separate isolates into groups that were structured with common bean gene pools. No genetic differentiation (G ST=0.03) was apparent between Andean and Mesoamerican isolates of C. lindemuthianum. The diversity exhibited by C. lindemuthianum does not appear to cluster according to common bean gene pools, and the high diversity found in the Mesoamerican region seems to indicate that C. lindemuthianum originated and was disseminated from this region. Due to the high genetic variation exhibited by C. lindemuthianum, stacking major resistance genes appears to be the best option for developing cultivars with durable anthracnose resistance.  相似文献   

2.
The slow growth rate of the fungus Phaeoisariopsis griseola and the availability of a homogeneous highly concentrated inoculum is an important constraint for pathogenicity or virulence studies, where plant inoculations are needed. Therefore, the purpose of this paper was to evaluate the effect of supplementing culture media with Amaranthus cruentus seed meal on fungal growth and sporulation of isolates of P. griseola belonging to the Mesoamerican and Andean groups. The amendment of PDA or V8 media with A. cruentus seed meal resulted in a considerable increase in the number of conidia and also in their capacity to germinate; this depended mostly on the stage of maturity of conidia. Mesoamerican and Andean isolates produced a different number of conidia when cultured in vitro. Furthermore, while in Mesoamerican isolates a second degree polynomial represented the relationship between number of conidia and amount of A. cruentus supplementation, in Andean isolates the relationship was linear. It seems that either one or several of the nutritional factors provided by A. cruentus contributed to the increased production of conidia and their development, resulting in faster development of the disease and an earlier appearance of symptoms. Therefore, for cultural studies, especially for inoculum production and for pathogenicity evaluations, supplementation of the media with A. cruentus seed meal proved to be a good alternative.  相似文献   

3.
为查明西藏小麦条锈菌Puccinia striiformis f. sp. tritici群体结构和遗传多样性,采用中国鉴别寄主和近等基因系鉴别寄主,以及竞争性等位基因特异性PCR-单核苷酸多态性（kompetitive al-lele specific PCR-single nucleotide polymorphism,KASP-SNP）分子标记对2017年采自西藏的150个小麦条锈菌菌系分别进行表型分析和基因型分析。表型分析结果显示,中国鉴别寄主将150个菌系区分为 12 个已知小种、6 个已知致病类型和 13 个未知致病类型,所有菌系均不能侵染中四和Triticum spelta album鉴别寄主。近等基因系鉴别寄主将150个菌系区分为88个毒性类型,这些毒性类型均不侵染携带抗性基因Yr5、Yr10或Yr15的品种。基因型分析结果显示,26对引物将150个菌系划分为73个基因型,表明西藏小麦条锈菌群体基因型丰富。基因流分析结果表明,波密县与洛扎县小麦条锈菌亚群体之间的基因流Nm最高,达5.86,米林县西部与波密县、洛扎县、巴宜县、米林县东部条锈菌亚群体之间的Nm较低,分别为0.25、0.34、0.42和0.67,表明西藏不同地区条锈菌群体之间基因交流强度差异较大。说明西藏作为我国小麦条锈病的独立流行区,条锈菌群体毒性结构复杂,遗传多样性高。  相似文献   

4.
The genetic structure of wild populations of Colletotrichum lindemuthianum was evaluated for virulence and molecular markers. Forty-five isolates were collected from five wild common bean populations located in their South-Andean centre of origin. The five pathogen populations were monomorphic in their ITS regions, but 45 polymorphic markers were identified using RAPDs. Polymorphism for virulence was also observed; 15 pathotypes were characterized on an international set of 12 differentials. A molecular variance analysis ( AMOVA ) showed that a very large part of the total genetic variation was within populations. Statistical analysis showed that there was a weak though significant differentiation among the five populations for the RAPD and virulence markers. A positive and significant correlation was found between geographic distance and the distances from RAPD and virulence data, suggesting migration between adjacent populations along the Argentinian transect. Our results suggest that the Andean wild isolates of C. lindemuthianum do not reflect all the putative diversity found in the isolates from cultivated common bean.  相似文献   

5.
The genetic and virulence variability of 112 isolates of Phaeoisariopsis griseola , collected from various locations in Central America, were studied using seven random amplified polymorphic DNA (RAPD) primers and 12 common-bean differential genotypes. Broad molecular diversity ( H  = 0·92) among isolates was found using RAPD markers. Fifty pathotypes were identified on 12 differential bean genotypes, 29 of which were represented by only one isolate. Only 18 pathotypes were found in two or more countries. Pathotype 63-63 was the most virulent and caused leaf spots on all 12 common-bean differential genotypes. Comparison of virulence phenotypes and RAPD profiles to known Andean P. griseola isolates confirmed that all isolates belonged to the Mesoamerican group. Pairwise comparison between individual RAPD loci showed that the majority were in gametic phase linkage disequilibrium, revealing that P. griseola maintains a genetic structure that is consistent with asexual reproduction. The molecular and virulence diversities of P. griseola isolates from Central America imply that using single resistance genes to manage angular leaf spot is inadequate and stacking resistance genes may be necessary to manage the disease effectively.  相似文献   

6.
A large collection of German rye leaf rust isolates was analysed to characterize the diversity, spatial variation and temporal dynamics of virulences. Virulence-avirulence phenotypes (=pathotypes) were determined on 23 host differentials. We found 93 pathotypes among 177 single-uredinial isolates in 2000, 201 pathotypes among 437 isolates in 2001, and 125 pathotypes among 213 isolates in 2002. In total, the 827 analyzed isolates represented 317 pathotypes. Frequency of virulences on the individual differentials varied from 2% to 97%. Eight of the differentials showed a high resistance level with virulence frequencies <10%. Virulence complexity of the isolates ranged from 3 to 21 with a mean of nine. The percentages of highly virulent isolates (>14 virulences) increased from 4 to 15% during the sampling period. A high level of virulence diversity was observed within and between individual sampling sites with Simpson indices around 0.9. Evenness indices ranged from 0.88 to 0.92. Four of the five most frequent pathotypes were found in each year but their frequency never exceeded 10%. Isolates with unusual virulence combinations could be clearly separated by principal component analysis. Location-specific pathotype frequencies were revealed in each year, but the frequency patterns varied across years. On four fields a considerable increase of highly virulent pathotypes occurred within 6 weeks during the epidemic. The high diversity of pathotypes as well as the fast accumulation of highly virulent pathotypes favour the adaptation of the pathogen to race-specific host resistances. More durable resistance might be achievable by combining new effective race-specific resistances with adult-plant and/or race-non-specific quantitative resistances.  相似文献   

7.
Five pathotypes belonging to formae speciales larici-epitea typica (LET), larici-retusae (LR) and larici-daphnoides (LD) of Melampsora larici-epitea were examined using amplified fragment length polymorphism (AFLP). Of 213 AFLP markers scored, several were found to be exclusive to different formae speciales. The dendrogram placed the five pathotypes into distinct groups. Within pathotypes, average Nei & Li's similarity coefficients were calculated as 0.71–0.85. The similarities were 0.66–0.72 among the three pathotypes within LET and 0.34–0.44 between pathotypes belonging to different formae speciales. When assessed using the Shannon index, the diversity within locations was estimated as 0.55–0.59, greater than that found within pathotypes (0.24–0.42). The average per-locus diversity was 0.37 among the pathotypes and 0.11 among the locations. When the data from both LET and LR isolates were examined using AMOVA, the majority of the variation (70.85%) was attributed to among pathotypes within location. When only LET types were included, approximately half of the variation was partitioned to among pathotypes within location and the other half to among the isolates within collection. It appears that the degree of differentiation of LET4 on S. × mollissima between Loughgall and Long Ashton sites has decreased markedly since 1992, when it was first detected.  相似文献   

8.
Potato wart disease, caused by the chytridiomycete Synchytrium endobioticum, was first introduced into Europe in the late 19th century. It spread quickly, and today is reported in 15 European countries. Initially, only one pathotype was found, and the disease was efficiently controlled using resistant cultivars. In 1941, however, formerly resistant cultivars showed wart formation in the field simultaneously in Germany and South Bohemia (Czech Republic), indicating the occurrence of new pathotypes. New pathotypes have since been reported from Germany, The Netherlands, Czech Republic, Ukraine and Canada. Today the pathogen is present in The Netherlands (only in fields for ware and starch potatoes) but restricted to two demarcated areas and subject to official control. Outside these areas, the pathogen is absent. For pathotyping, different countries have used different sets of differential cultivars, and the usual system of numerical coding of pathotypes has not been consistently followed. In this review we propose a new standardised code to be used for the 43 pathotypes currently known and described in Europe. The code is a combination of a numerical and letter code, combining the two terminologies used by former West and East Germany, respectively. We also plead for harmonisation in the choice of differential cultivars used for pathotype identification. The set of differentials described in the international standard for diagnosis of S. endobioticum issued by the European and Mediterranean Plant Protection Organisation (EPPO), should serve as a basis. Through close collaboration of European countries dealing with new pathotypes of potato wart disease, a final agreed upon set of differentials, combined with a set of reference isolates, should ultimately be established, allowing a clear distinction between the most important pathotypes occurring in Europe.  相似文献   

9.
Phakopsora pachyrhizi is a biotrophic fungus that causes rust on soybean, leading to devastating yield losses. Development of resistant cultivars for deployment in different geographic regions requires a comprehensive understanding of the prevalent P. pachyrhizi pathotypes. To determine the pathotypes existing in four East African countries, 65 isolates were tested on 11 soybean host differentials. In addition, the virulence spectrum of isolates collected from the same region over multiple years was compared. The majority of the isolates (54%) belonged to pathotype 1000, which was found in all countries. The pathotypes with the most complex virulence spectrum, which comprised isolates from Kenya and Malawi, were virulent on four differentials. All pathotypes were virulent on soybean genotypes carrying the Rpp1 resistance gene to P. pachyrhizi, but they were avirulent on cultivars carrying the Rpp1b, Rpp2, or Rpp3 gene, as well as on cultivar No6-12-1 that carries Rpp2, Rpp4, and Rpp5. Two of the pathotypes were virulent on cultivar UG 5 that carries Rpp1 and Rpp3 and on Hyuuga that carries Rpp3 and Rpp5. The isolates collected from different countries differed in their virulence spectrum across the years. Shannon's index (H) and Simpson's index (S) of diversity indicated that the isolates from Malawi were more diverse (H = 1.55, S = 0.90) while those from Uganda had lower diversity (H = 0.78, S = 0.46 ). The Rpp genes that were found to provide resistance to all pathotypes of P. pachyrhizi can be employed for soybean breeding aimed at durable rust resistance.  相似文献   

10.
Tan spot, caused by Pyrenophora tritici-repentis, is a common disease of wheat (Triticum aestivum) responsible for economic losses in some wheat growing areas worldwide. In this study the pathogenic and genetic diversity of 51 P. tritici-repentis isolates collected from different ecological regions of Argentina were analyzed. Virulence tests were conducted on 10 selected wheat cultivars: Buck Halcón, Chris, Gabo, Glenlea, Klein Dragón, Klein Sendero, Max, ND 495, ProInta Guazú and ProInta Imperial. Data revealed significant differences between all main factors evaluated and the interactions for 19 of the isolates analyzed. Based on the reaction type of each isolate/cultivar combination, 48 different pathogenic patterns were detected. The molecular analysis using Inter-Simple Sequence Repeats (ISSR) revealed the existence of 36 different haplotypes among 37 isolates of P. tritici-repentis originally selected for this study. These results indicate that P. tritici-repentis on wheat in Argentina is a heterogeneous fungus, implying that screening wheat germoplasm for resistance for tan spot disease requires a wide range of pathogen isolates.  相似文献   

11.
Molecular diagnostic techniques have been developed to differentiate the Ascochyta pathogens that infect cool season food and feed legumes, as well as to improve the sensitivity of detecting latent infection in plant tissues. A seed sampling technique was developed to detect a 1% level of infection by Ascochyta rabiei in commercial chickpea seed. The Ascochyta pathogens were shown to be genetically diverse in countries where the pathogen and host have coexisted for a long time. However, where the pathogen was recently introduced, such as A. rabiei to Australia, the level of diversity remained relatively low, even as the pathogen spread to all chickpea-growing areas. Pathogenic variability of A. rabiei and Ascochyta pinodes pathogens in chickpea and field pea respectively, appears to be quantitative, where measures of disease severity were based on aggressiveness (quantitative level of infection) rather than on true qualitative virulence. In contrast, qualitative differences in pathogenicity in lentil and faba bean genotypes indicated the existence of pathotypes of Ascochyta lentis and Ascochyta fabae. Therefore, reports of pathotype discrimination based on quantitative differences in pathogenicity in a set of specific genotypes is questionable for several of the ascochyta-legume pathosystems such as A. rabiei and A. pinodes. This is not surprising since host resistance to these pathogens has been reported to be mainly quantitative, making it difficult for the pathogen to overcome specific resistance genes and form pathotypes. For robust pathogenicity assessment, there needs to be consistency in selection of differential host genotypes, screening conditions and disease evaluation techniques for each of the Ascochyta sp. in legume-growing countries throughout the world. Nevertheless, knowledge of pathotype diversity and aggressiveness within populations is important in the selection of resistant genotypes.  相似文献   

12.
Knowledge of pathotype diversity and virulence in local populations of Pyrenophora teres is a prerequisite to screening for durable resistance to net blotch. The current study aimed to quantify the virulence level of Moroccan isolates, identify and designate existing pathotypes, and select resistant genotypes. We developed a method for virulence quantification of P. teres isolates based on a conversion of infection responses into frequencies for use in correspondence analysis. Coordinates of the first axis of this analysis had a virulence spectrum and ranked isolates from virulent to avirulent. Mixed model analysis was also devised for virulence quantification. Coordinates of the first dimension of correspondence analysis were linearly correlated to BLUPs (Best Linear Unbiased Predictors) of the mixed model. A genotype by genotype by environment model (GGE) coupled with cluster analysis differentiated P. teres isolates into ten and nine pathotypes for net- and spot-forms respectively. Populations of these two forms were dissimilar in terms of classes of virulence. For P. teres f. maculata, avirulent, moderately virulent and highly virulent isolates represented one-third of the population, whereas 90% of P. teres f. teres population was composed of avirulent to moderately avirulent isolates. Barley differential sets were subsequently reduced to two new sets that simplified pathotyping through a key code based on resistant or susceptible reactions. Dendrograms of cluster analysis based on GGE analysis depicted the stability of a genotype’s reactions across all isolates, and using only resistant cultivars as sources of resistance to control net blotch disease would, based on this analysis, fail to control all pathotypes. Therefore, we propose an alternative breeding strategy to control net blotch effectively.  相似文献   

13.
White mould, caused by Sclerotinia sclerotiorum, is one of the most threatening fungal diseases occurring across major bean production regions worldwide. In Argentina, under favourable weather conditions, up to 100% seed yield losses occur on susceptible common bean cultivars. The aim of this study was to characterize the diversity of S. sclerotiorum isolates from six dry bean fields in the main production area of Argentina by means of molecular, morphological (mycelium colour, number and pattern of sclerotia distribution) and pathogenic approaches. Among 116 isolates analysed, high genotypic and morphological variability was observed. A total of 52 mycelial compatibility groups (MCGs) and 59 URPs (universal rice primers) molecular haplotypes were found. All the MCGs were location specific, while only 12% of the URP haplotypes were shared among locations. The molecular analysis of variance revealed a significant differentiation among populations, with higher genetic variability within the populations analysed than among them. The aggressiveness of the isolates towards bean seedlings was assessed in the greenhouse. Most of the isolates were highly aggressive, while no variation among locations was observed. The information generated in the present study provides, for the first time, information on the variability of S. sclerotiorum associated with white mould in the main common bean production area in Argentina. In addition, the findings suggest the occurrence of both clonal and sexual reproduction in the populations analysed. This work contributes to the development of sustainable management strategies in bean production aimed to minimize yield losses due to white mould.  相似文献   

14.
Angular leaf spot (ALS), an important disease of common bean (Phaseolus vulgaris), is caused by the fungus Pseudocercospora griseola. This pathogen has a wide genetic variability and, therefore, poses a challenge to integrated disease management. The use of resistant cultivars is difficult; hence, the application of fungicides has been a common practice in common bean cultivation. P. griseola strains were morphophysiologically characterized and their sensitivity to common fungicides used to control ALS was studied. The strains were evaluated for sporulation capacity and a representative sample of 34 strains was bioassayed to determine their sensitivity to commercial concentrations of five fungicides, namely pyraclostrobin, mancozeb, pyraclostrobin + metconazole, chlorothalonil and tebuconazole. Another sample of 29 strains was studied for conidial germination and dimensions. Sporulation capacity ranged from 0.88 to 27.67 × 104 conidia/ml and germination percentage ranged from 39% to 72%. The large differences among strains suggest a wide genetic variability among the strains. A wide variability in aggressiveness of P. griseola was observed, which has consequences for breeding programmes aimed at resistance. The behaviour of pathogen strains differed in every fungicide evaluated, even in a population that has not been under selection pressure in the field. These results confirm the need for further studies and may guide future research with this pathogen.  相似文献   

15.
Rice blast caused by Pyricularia oryzae is a devastating disease worldwide. In Vietnam, rice blast is especially severe in the Red River Delta in the North. The genetic diversity of 114 P. oryzae isolates collected from rice in 2001 in the Red River Delta and nine additional Vietnamese P. oryzae isolates was analysed using Amplified Fragment Length Polymorphism (AFLP). DNA similarity and cluster analysis based on 160 polymorphic AFLP markers showed twelve different AFLP genetic groups among the 123 field isolates. Isolates collected from japonica hosts clustered separately from indica host isolates with at least 60% dissimilarity with little evidence for gene flow between the two populations. In the 2001 population originating from indica hosts, three genetic groups were predominant and represented 99% of the isolates sampled. One predominant clonal lineage represented 59% of the 2001 indica host population and was found in eleven provinces in the Red River Delta of North Vietnam. Significant genotype flow could be demonstrated between the indica population south of Red river and the indica population north of Red river. There was significant linkage disequilibrium between the AFLP loci within the indica population, indicating that this is not a random mating population. Pathogenicity tests of 25 isolates selected from the 12 AFLP groups on a set of 29 differential rice lines revealed two avirulent isolates and 23 pathotypes. Different combinations of known resistance genes were found to have potential for blast resistance breeding for North Vietnam. First two authors contributed equally  相似文献   

16.
Amplified fragment length polymorphism (AFLP) based genetic diversity was analyzed for 232 Colletotrichum sublineolum isolates collected between 2002 and 2004 from three geographically distinct regions of Texas, and from Arkansas, Georgia, and Puerto Rico. Results revealed significant levels of polymorphism (59%) among the isolates. Even so, genetic similarity between isolates was high, ranging from 0.78 to 1.00. Clustering of similar isolates did not correlate with either geographic origin or year of collection. Pathotypes of 20 of the isolates were determined using 14 sorghum lines previously used in Brazil and the United States and 4 from Sudan. Seventeen new pathotypes were established from the 18 isolates that gave uniform and consistent reactions on all host differentials over 2?years of greenhouse testing. Differentials BTx378 and QL3 were resistant to all isolates while BTx623 and TAM428 were universally susceptible both years. Each of these lines had shown differential responses in prior studies indicating that the pathogen population has sufficient diversity to adapt rapidly to changes in resistant host lines deployed. When the 2-step pathotype classification scheme was used, the 18 isolates examined in this study were placed in four pathotype groups (A, C, D and G), which would further then be separated into ten distinct pathotypes. Common sets of differentials and a standardized nomenclature will allow for comparison to be made among pathotypes of C. sublineolum detected from different regions and also could help direct planting of appropriate sorghum lines and aid in the development of more durable forms of resistance.  相似文献   

17.
为明确水稻抗性基因Piz-t、Pib和Pii的有效性,利用无毒基因AvrPiz-t、AvrPib和Avr-Pii的特异性引物对自云南省6个水稻产区采集并分离获得的348株稻瘟病菌Magnaporthe oryzae菌株进行PCR扩增检测,并测定其对仅含Piz-t、Pib和Pii基因的水稻抗性单基因系IRBLzt-T、IRBLb-B和IRBLi-F5品种的致病性,明确这3个无毒基因在云南省水稻产区组成及分布。结果表明,在348株稻瘟病菌菌株中,分别有51.7%、46.8%和15.8%的菌株含有无毒基因AvrPiz-t、AvrPib和Avr-Pii,GT8、GT2、GT5、GT6、GT1、GT3、GT4和GT7基因型菌株检测频率分别为24.7%、21.8%、21.0%、16.7%、4.9%、4.0%、3.4%和3.4%;分别有4.9%、29.2%、41.1%和24.7%的菌株含有3、2、1和0个无毒基因;云南省稻瘟病菌群体总多样性指数水平较高,为2.81,其中滇中水稻产区的最高,为2.97;在348株稻瘟病菌菌株中,分别有89.1%、63.2%和38.5%的菌株对单基因系IRBLzt-T、IRBLb-B和IR‐BLi-F5表现为不致病,表明对Piz-t基因和Pib基因的抗性利用价值较Pii基因高;PT1、PT2、PT3、PT4、PT5、PT6、PT7和PT8致病型菌株检测频率分别为23.0%、30.2%、8.9%、2.0%、21.8%、5.2%、4.6%和4.3%,其中PT2、PT1和PT5为云南省稻瘟病菌的主要致病型。表明云南省6个水稻产区稻瘟病菌3个无毒基因的分布及组成差异较大,群体多样性水平较高。  相似文献   

18.
Forty-eight chickpea germplasm lines, including 22 differentials used in previous studies, were characterized for disease phenotypes following inoculation with six isolates of Didymella (anamorph Ascochyta ) rabiei , representing a wide spectrum of pathogenic variation. Representative isolates were also directly compared with six previously identified races on eight chickpea genotypes. Many of the chickpea differentials reacted similarly to inoculation with each isolate of D. rabiei , and several previously identified races caused similar levels of disease on the differentials. This indicates that the number of differentials can be reduced significantly without sacrificing accuracy in describing pathogenic variation of D. rabiei on chickpea. Pathogenic variation among samples of US isolates allowed classification of the isolates into two pathotypes. The distribution of disease phenotypes of the 48 germplasm lines was bimodal after inoculation with pathotype I isolates, whereas the distribution of disease phenotypes was continuous after inoculation with pathotype II isolates. Such distinct distribution patterns suggest that chickpea plants employ different resistance mechanisms to each pathotype and that the two pathotypes may have different genetic mechanisms controlling pathogenicity. The advantages of using the two-pathotype system in assaying pathogenicity of the pathogen and in studying resistance mechanisms of the host are discussed. Three chickpea accessions, PI 559361, PI 559363 and W6 22589, showed a high level of resistance to both pathotypes, and can be employed as resistance sources in chickpea breeding programmes for resistance to ascochyta blight.  相似文献   

19.
In this study, the Estonian population of Phytophthora infestans was characterized with mating type, sensitivity to metalaxyl, virulence on 11 potato R-gene differentials and 12 SSR markers to show the outcome of potential sexual reproduction in the population. During the three years 2010–2012, 141 P. infestans isolates, collected from 23 potato fields, showed quite a high and stable frequency of the A2 mating type, 48% of the total population. In 87% of all sampled potato fields, both mating types were recorded, suggesting continuous sexual reproduction of P. infestans and possible oospore production. Metalaxyl-sensitive isolates prevailed in all three years (68 out of 99 isolates). Amongst the 95 isolates tested, 51 virulence races were found. The race structure was diverse, and most pathotypes were unique, appearing only once; the two most common pathotypes, 1.2.3.4.6.7.10.11 and 1.2.3.4.7.10.11, comprised 35% of the population. The P. infestans population was genetically highly diverse and most of the multilocus genotypes (MLGs) appeared only once. Furthermore, all of the MLGs appeared in only one of the three sampling years. Our results confirm that the high diversity in the Estonian P. infestans population is most likely the result of frequent sexual reproduction, which benefits the survival, adaptability and diversity of the pathogen in the climate of North-Eastern Europe.  相似文献   

20.
Yellow rust, caused by Puccinia striiformis f.sp. tritici (PST), is an important disease that threatens wheat production in Pakistan. This study was designed to explore the virulence and simple sequence repeat (SSR) diversity of the Pakistani PST population and the ongoing selective pressures of widely grown wheat cultivars. Analyses of 49 isolates sampled from the North‐West Frontier Province of Pakistan led to the identification of 12 distinct pathotypes. The virulence frequencies of v2 (virulent against Yr2), v6, v7, v9, vSU and v27 ranged from 63% to 100%. Virulences v3, v4, v17 and vSD were uncommon, whilst v5, v10, v15, v24, v32 and vSp were not detected. The pathotypes thus described were then classified into 27 distinct genotypes. Bayesian structure analysis clustered these genotypes into five groups (in addition to one hybrid isolate) which represent three distinct lineages of the SSR‐based phylogenetic tree. Of the studied isolates, 80%, represented by three predominant pathotypes (P1–P3), belonged to the same characteristic Pakistani lineage, whilst the other isolates were close to either a Mediterranean lineage or a Northern European lineage. Genetic recombination was detected within P2 isolates. Resistance genes postulated in 40 Pakistani wheat cultivars indicated the high frequency of Yr2, Yr6, Yr7, Yr9, Yr27 and YrSU. Only 11 cultivars were found to be resistant to P1–P3. Migration and varietal diversity factors might contribute to maintaining the currently high genetic diversity in Pakistani PST, and have serious regional implications for wheat improvement programmes.  相似文献   

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