Molecular characterization of <Emphasis Type="Italic">Phoma tracheiphila</Emphasis>, causal agent of Mal secco disease of citrus,in Israel

Mal secco disease of citrus caused by Phoma tracheiphila is a devastating disease in the Mediterranean basin. Susceptible citrus species include lemon, citron, lime and others. Trees attacked by the fungus show characteristic symptoms; the smallest twigs die first, followed by the larger branches. Eventually, the whole tree is killed. The symptoms are clear in the orchards but by the time they are visible the disease is already well established. The need for a sensitive, reliable and rapid diagnostic method for the early identification of the fungus in trees and fruit exists. We have developed a PCR-based method for the identification of P. tracheiphila from plant tissues including fruit. Any such method must take into account the genetic variability in the pathogen population. Molecular methods were used to compare different isolates of P. tracheiphila. This study found no significant differences between different isolates from different citrus species from different parts of Israel.     

四川西南部小麦白粉菌群体毒性及遗传多样性分析

为明确四川西南部白粉菌群体毒性及其遗传变异情况,本文将2011年采自四川西南部的小麦白粉病标样进行单孢子堆分离纯化,共获得48个白粉菌菌株,并将其按采集地划分为4个地理群体。利用28份已知抗白粉病基因材料测定了群体的毒性频率,并运用SRAP分子标记技术探讨了其遗传多样性。毒性测定结果表明,白粉菌群体毒性较强,群体间毒性结构存在差异。供试群体对Pm1、Pm3a、Pm3b、Pm3d、Pm5a、Pm6、Pm19的平均毒性频率达50%以上,而Pm13、Pm XBD、Pm5b、Pm2+6、Pm5+6抗性保持良好,平均毒性频率在10%以下。群体间毒性遗传距离与地理距离之间有一定的相关性,但未达到显著水平。用筛选出的10对SRAP引物共获得160个清晰、稳定的扩增位点,多态性频率为50.63%;白粉菌群体遗传多样度(h)、Shannon信息指数(I)分别为0.198 8、0.322 7,遗传变异主要源于群体内部。群体间基因流数值均在6.50以上,说明四川西南部白粉菌群体间菌源迁移频繁,基因交流较为充分。M antel Test分析表明SRAP标记解释的群体遗传多样性与地理距离、毒性多样性间的相关性未达到显著水平。     

High diversity, low spatial structure and rapid pathotype evolution in Moroccan populations of Blumeria graminis f.sp. hordei

Limited information is available about the spatial distribution and evolution of Blumeria graminis f.sp. hordei populations in North African countries, such as Morocco. Frequencies of virulence alleles in B. graminis populations are mainly driven by selection exerted by host resistance genes in addition to neutral processes such as migration and genetic drift. In Morocco, in contrast to Europe, there has been no systematic deployment of resistant cultivars, although some R genes are present in the traditional varieties. This is expected to result in the evolution of pathotypes with virulence to different R genes, and higher diversity in Morocco compared to Europe. To test this, we used 24 differential cultivars to characterise 72 isolates from Morocco in 2009. We assessed diversity and spatial structure of pathotypes and compared them to past isolates from the same area (collected in 1992). There was a high diversity of pathotypes. Isolates from 2009 were distinct from isolates from 1992, due to loss of virulence to Mla12, increased virulence to Mla8, Mla3 and Mlk1, and decreased virulence to Mla6, Ml(Ru2), Mlg and MlLa. Many virulences were different from those observed in European and Asian populations of B. graminis. At the spatial scale investigated, airborne dispersal and a lack of strong selection in the host population likely prevented the formation of population structure and allowed the accumulation of high isolate diversity. The evolution of novel and distinct pathotypes since 1992 is likely attributable to gene flow from Europe and selection by the host population in Morocco.     

Molecular evidence supports hypervariability in Phytophthora colocasiae associated with leaf blight of taro

The oomycete Phytophthora colocasiae that causes taro leaf blight is the most devastating disease of taro and is widely distributed worldwide. Molecular and phenotypic techniques were employed for assessing and exploiting the genetic variability among four populations of P. colocasiae obtained from a fine spatial scale (multiple leaf blight lesions on single taro leaf). Phenotypic characters such as virulence, morphology and mating type showed no variation. ITS characterization revealed detectable polymorphism among isolates of P. colocasiae. The mean number of haplotypes (H), haplotype diversity (HD), nucleotide diversity (π), and nucleotide substitution rate (θ) among analyzed sequences were 6.75, 1.00, 0.069, and 0.088 respectively. High levels of inter and intra specific variation were detected by random amplified polymorphic DNA (RAPD) assays. Moderate genetic diversity (H?=?0.2651) was observed among populations of P. colocasiae. Analysis of molecular variance (AMOVA) confirmed that most of the genetic variability was confined to within a population (63.54 %). The coefficient of genetic differentiation among populations (G _ST ) was 0.2007 and estimates of gene flow (Nm) among populations was 1.991 migrants per generation. Cluster analysis using UPGMA revealed that individuals from the same population failed to cluster in one distinct group. The results of the study reveal considerable genetic diversity among and within populations of P. colocasiae obtained from fine spatial scale. The possible mechanisms and implications of this genetic variation are discussed.     

Diversity among isolates ofVerticillium lecanii as expressed by DNA polymorphism and virulence towardsBemisia tabaci

Thirty-six isolates ofVerticillium lecanii andVerticillium sp. were taken from different hosts (both insects and rusts) and geographical locations. The isolates were analyzed for genomic variability, as expressed by random amplified polymorphic DNA (RAPD), in relation to virulence onBemisia tabaci. Virulence on larvae ofB. tabaci within these isolates ranged from 0% to 83%. RAPD analysis was performed employing two different arbitrary decamer primers and the calculated similarity coefficients were subjected to cluster analysis using the unweighted average linkage (UPGMA) algorithm. The dendrograms obtained with each of the two primers were identical. Eight cluster groups and three unclustered isolates were obtained by selecting a similarity level of 80%. The amplification pattern of DNA obtained by RAPD for the various isolates suggested thatV. lecanii is a highly diverse species. No correlation could be established between virulence and either RAPD polymorphism of the fungal isolates or the insect host from which they were isolated. Generally, no correlation could be established between the clustering ofV lecanii strain and geographical location although a limited number of strains obtained from Russia and Georgia were assembled in the same cluster and those from Kazakhstan were clonal.     

Genetic and virulence diversity, and mating type distribution of Togninia minima causing grapevine trunk diseases in Spain

Fifty eight single-spore Togninia minima (anamorph Phaeoacremonium aleophilum) isolates were recovered from grape rootstock wood of plants that showed symptoms of Petri disease and esca from 2001 to 2008 in Spain. These isolates were studied by means of mating type distribution, UP-PCR analysis, and virulence assays. Analysis of clone-corrected data sets showed equal frequencies of both mating types in the entire Spanish population, in the Ciudad Real region, at inter-vineyard and intra-vine spatial scales; while unequal mating type distribution was detected in Valencia and Zaragoza regions, at intra-vineyard and intra-vine spatial scales. This is the first study on distribution of T. minima mating types on spatial scales varying from vineyards to regions. A total of 49 polymorphic UP-PCR markers were obtained using seven UP-PCR primers. Four optimal clusters were inferred with Bayesian structure and multivariate analyses from the UP-PCR data. The high number of unique genotypes observed within the Spanish population, combined with a near-equal distribution of mating types, suggested that sexual reproduction probably does occur. However, based on allele distribution and frequency, each of the three subpopulations appeared to be evolving independently. Gene and genotype diversities across the subpopulations were similar and ranged from 0.24 to 0.27 and from 0.27 to 0.37, respectively. The detection of genetically identical isolates within and among subpopulations indicates that an asexual reproductive component should not be excluded. Contrast analysis among groups defined by UP-PCR analyses showed no significant differences in the virulence of T. minima isolates.     

Genetic differentiation of the wheat leaf rust fungus Puccinia triticina in Europe

The objective of this study was to determine whether genetically differentiated groups of Puccinia triticina are present in Europe. In total, 133 isolates of P. triticina collected from western Europe, central Europe and Turkey were tested for virulence on 20 lines of wheat with single leaf rust resistance genes, and for molecular genotypes with 23 simple sequence repeat (SSR) markers. After removal of isolates with identical virulence and SSR genotype within countries, 121 isolates were retained for further analysis. Isolates were grouped based on SSR genotypes using a Bayesian approach and a genetic distance method. Both methods optimally placed the isolates into eight European (EU) groups of P. triticina SSR genotypes. Seven of the groups had virulence characteristics of isolates collected from common hexaploid wheat, and one of the groups had virulence characteristics of isolates from tetraploid durum wheat. There was a significant correlation between the SSR genotypes and virulence phenotypes of the isolates. All EU groups had observed values of heterozygosity greater than expected and significant fixation values, which indicated the clonal reproduction of urediniospores in the overall population. Linkage disequilibria for SSR genotypes were high across the entire population and within countries. The overall values of R_ST and F_ST were lower when isolates were grouped by country, which indicated the migration of isolates within Europe. The European population of P. triticina had higher levels of genetic differentiation compared to other continental populations.     

Scientific critique of the paper “Climatic distribution of citrus black spot caused by <Emphasis Type="Italic">Phyllosticta citricarpa</Emphasis>. A historical analysis of disease spread in South Africa” by Martínez-Minaya et al. (2015)

The global distribution of citrus black spot (CBS) disease, caused by Phyllosticta citricarpa, is climatically constrained, which is evident from its occurrence in citrus growing areas with warm, summer rainfall and its absence from areas with cooler, Mediterranean-type winter rainfall. Various epidemiological and modelling studies have supported this observation, predominantly estimating unsuitability for P. citricarpa in Mediterranean type climates, with no more than marginal suitability estimated at a few localities within some regions with Mediterranean type climates. The study by Martínez-Minaya et al. (European Journal of Plant Pathology, 143, 69–83, 2015), describes an historic sequence of recorded CBS occurrence in parts of South Africa, conducts an autocorrelation analysis and a correlative analysis with Köppen-Geiger climate zones and makes observations about the occurrence of certain Köppen-Geiger climate zones in the European Union. The study suggests that significant portions of the European Union and the broader Mediterranean basin are climatically similar to warm, summer rainfall areas in South Africa where P. citricarpa persists and causes CBS disease and concludes that the potential distribution of P. citricarpa is less constrained by climatic factors than spatial contagion. However, in this critique we expose methodological shortcomings in the Martínez-Minaya et al. (European Journal of Plant Pathology, 143, 69–83, 2015) study and conclude that the study grossly overestimated the extent of the geographical area that could support P. citricarpa, thereby rendering the findings scientifically unreliable.     

Morphological and pathogenic characterization of Corynespora cassiicola isolates reveals specific genotypic interactions in soybean

Soybean target spot, caused by the fungus Corynespora cassiicola, is an important disease in northwestern Argentina (NWA). A cultural, morphological, and virulence characterization of 24 C. cassiicola isolates from different geographic localities in NWA was performed. The isolates were classified into five different cultural phenotypes, one of which has not been previously described. The ribosomal DNA internal transcribed spacer region sequence from five representative isolates (587 bp) exhibited 100% identity with C. cassiicola. A high variability of conidial morphology was observed among isolates, but no correlation with cultural phenotype was observed. When the soybean cultivar A 8000 RG was challenged with the 24 isolates, different degrees of virulence were observed, ranging from highly virulent to nonvirulent. No association of virulence with cultural or morphological characters was observed, but a relationship with geographical origin was demonstrated. Histopathological studies were performed on a nonvirulent and a highly virulent isolate. Microscopic observations of infected tissues of the former showed low mycelium development restricted to the upper epidermis, a thickening of the cuticle and primary wall of subepidermal cells, and accumulation of callose in phloematic vessels. In tissue infected with the latter, there was abundant mycelium development accompanied by cellular disorganization in mesophyll cells. Pathological challenges of isolates on nine different cultivars indicated that the degree of virulence of isolates depends on the plant genotype, demonstrating that the C. cassiicola–soybean interaction is highly specific. Understanding the genetic basis of this interaction will provide new information for better disease management and breeding strategies.     

Identification and characterization of Phoma tracheiphila mutants impaired in pathogenicity following Agrobacterium-mediated mutagenesis

Mal secco disease, caused by the pathogenic fungus Phoma tracheiphila, is a devastating disease of susceptible citrus species, especially lemon. To study the molecular interactions between the pathogen and its host, a method for identifying the genes involved in pathogenicity is needed. This work describes the transformation of P. tracheiphila phialoconidia by Agrobacterium tumefaciens, and the generation of mutated P. tracheiphila isolates exhibiting reduced virulence on rough lemon seedlings. A rapid, replicable, and reliable method for screening P. tracheiphila mutants to assess their virulence by using rough lemon seedlings was developed. Among 2263 transformants obtained, three were non-virulent and 43 displayed reduced virulence. In addition, one of the transformants, which exhibited virulence similar to that of the wild type, was used for in planta visualization of the fungus progression through the plant xylem. To our knowledge, this is the first report of A. tumefaciens-mediated transformation of P. tracheiphila, and subsequent screening of the transformants to identify non-virulent mutants.     

Genetic diversity and aggressiveness of Erwinia psidii on Eucalyptus spp. in Brazil

The genetic variability and aggressiveness of Brazilian Erwinia psidii isolates from Eucalyptus spp. was studied and compared with reference isolates from guava (Psidium guajava). Repetitive element sequence (rep)-based PCR markers of 101 isolates from Eucalyptus spp. and five from guava showed that the populations of E. psidii displayed a relatively low genetic variability. No correlation of genetic clustering based on rep-PCR analysis with geographic origin or host of origin was observed, indicating that genome rearrangements associated with adaptation to a particular host were not detected by these molecular markers. A higher genotypic richness was detected in the Mato Grosso do Sul population, probably reflecting a pathogen dissemination associated with the recent expansion in eucalypt plantations. Wilcoxon and ANOVA tests of disease severity data indicated differences in aggressiveness among isolates and an isolate × clone interaction. The area under the disease progress curve (AUDPC) and disease severity for some isolates were significantly different between two susceptible clones tested. Notably, isolate LPF681 from guava was not able to cause disease on a susceptible Eucalyptus urophylla clone, suggesting that some co-evolution between pathogen and host has taken place. The variability in aggressiveness and virulence among isolates of E. psidii observed in this study will be important for the establishment of appropriate screening approaches to select for disease resistance.     

Morphological and molecular variability among Indian isolates of <Emphasis Type="Italic">Rhizoctonia solani</Emphasis> causing banded leaf and sheath blight in maize

Rhizoctonia solani, a devastating soil borne fungus inciting banded leaf and sheath blight (BLSB) disease is a constraint in maize production and improvement program. Rhizoctonia isolates collected from seven diverse maize cropping zones of India were examined for morphological and molecular variability. All the tested isolates caused symptoms of BLSB on maize and were also cross infective on rice and sugarcane hosts, but showed significant variability in hyphal diameter, mean hyphal cell size, weight, size and distribution of scleorotia, culture pigmentation, incubation period, pathogenicity and expression of symptoms. Neighbour joining cluster analysis placed the 62 isolates of R. solani into four major groups, A, B, C and D. Group A was more diverse and included isolates of diverse agro-ecological zones. The cluster analysis corresponded well with principle component analysis. Pathogenicity testing of R. solani isolates on maize genotype (CM 501) revealed highly variable virulence pattern of the pathogen population suggesting its high evolutionary potential, and hence adaptability to diverse geographical regions. The study reveals a strong evidence of inherent potential of the R. solani isolates to survive in diverse ecological zones and its probable spread to other maize cultivars across India. Sequence comparisons of the internal transcribed sequence-ribosomal DNA region of 62 isolates did not reveal much diversity among the isolates. Majority of the isolates (n?=?61) clustered together with anastomosis group (AG) AG1-IA used as reference strain in the phylogram, distinct from AG1-IB, AG2–2IIIB and Waitea circinata used as reference strains. BLSB isolates representing distinct geographical locations shared identical sequences indicating long-distance dispersal of the pathogen. The study confirms that the genetic flexibility of the pathogen allows for its adaptation to variable ecological niches and long-distance introduction of new genotypes into the region. The study emphasizes that epidemiological studies may complement the molecular studies.     

Outcome of sexual reproduction in the <Emphasis Type="Italic">Phytophthora infestans</Emphasis> population in Estonian potato fields

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.     

Development of molecular markers based on retrotransposons for the analysis of genetic variability in Moniliophthora perniciosa

Moniliophthora perniciosa is a fungus that causes witches?? broom disease (WBD) in the cacao tree (Theobroma cacao). The M. perniciosa genome contains different transposable elements; this prompted an evaluation of the use of its retrotransposons as molecular markers for population studies. The inter-retrotransposon amplified polymorphism (IRAP) and retrotransposon-microsatellite amplified polymorphism (REMAP) techniques were used to study the variability of 70?M. perniciosa isolates from different geographic origins and biotypes. A total of 43 loci was amplified. Cluster analysis of different geographical regions of C biotype revealed two large groups in the state of Bahia, Brazil. Techniques using retrotransposon-based molecular markers showed advantages over previously used molecular techniques for the study of genetic variability in M. perniciosa.     

Genetic and phenotypic diversity of Mediterranean populations of the olive knot pathogen,Pseudomonas savastanoi pv. savastanoi

Pseudomonas savastanoi pv. savastanoi (Psav) is a member of P. syringae sensu lato, and causes olive knot disease, a disease first reported over 2000 years ago. Analysing 124 isolates of Psav from 15 countries by rep‐PCR, the population genetic structure of Psav was investigated. A total of 113 distinct fingerprints were detected. Cluster analysis revealed the existence of two clusters and four subclusters. These clusters were associated with the geographic origin of isolates, which in turn correspond to historic human migration events and trade routes across the Mediterranean Sea. In contrast, multilocus sequence typing (MLST) of 2788 bp of the gapA, gltA, gyrB and rpoD genes found only one variable site among 77 representative isolates. Virulence variation was observed within the Psav population, with the most virulent strains generating knots that had a weight that was 10‐fold greater than those generated by the least virulent strains. Taken together, these data suggest that today's Psav population is the result of clonal expansion of a single strain, that moderate migration of the pathogen occurred between countries, and that changes in virulence arose during its evolution.     

Lack of host specificity of Colletotrichum spp. isolates associated with anthracnose symptoms on mango in Brazil

The aim of the present study was to analyse the genetic and pathogenic variability of Colletotrichum spp. isolates from various organs and cultivars of mango with anthracnose symptoms, collected from different municipalities of São Paulo State, Brazil. Colletotrichum gloeosporioides isolates from symptomless citrus leaves and C. acutatum isolates from citrus flowers with post‐bloom fruit drop symptoms were included as controls. Sequencing of the ITS region allowed the identification of 183 C. gloeosporioides isolates from mango; only one isolate was identified as C. acutatum. amova analysis of ITS sequences showed larger genetic variability among isolates from the same municipality than among those from different populations. fAFLP markers indicated high levels of genetic variability among the C. gloeosporioides isolates from mango and no correlation between genetic variability and isolate source. Only one C. gloeosporioides mango isolate had the same genotype as the C. gloeosporioides isolates from citrus leaves, as determined by ITS sequencing and fAFLP analysis. Pathogenicity tests revealed that C. gloeosporioides and C. acutatum isolates from either mango or citrus can cause anthracnose symptoms on leaves of mango cvs Palmer and Tommy Atkins and blossom blight symptoms in citrus flowers. These outcomes indicate a lack of host specificity of the Colletotrichum species and suggest the possibility of host migration.     

Multiparametric analysis of diversity in <Emphasis Type="Italic">Botrytis cinerea</Emphasis> isolates from Israel

The necrotrophic fungus Botrytis cinerea, known as the causal agent of gray mold, is ranked second for its phytopathological global-impact. The disease is controlled by cultural means and fungicides, however, these techniques have variable effect on different fungal isolates due to the plasticity of the pathogen populations. Here we studied and characterized the genetic and virulence associated variability of B. cinerea isolates from different sources. Starting from initial survey of 31 B. cinerea isolates, collected from seven hosts in different locations of Israel, we have focused on 10 isolates that exhibited potential phytopathogenic variability. Two genetic markers (microsatellite) Bc1 and Bc7, were able to differentiate between these isolates. Our analysis demonstrates significant variability in saprophytic growth rate, necrotrophic growth rate on tomato leaves and stems, and in the incidence of infection on leaves of whole plants. Following the observation of significant correlation between saprophytic growth rate, and necrotrophic growth on leaves, we have studied normalized (by saprophytic growth) virulence. Utilization of normalized necrotrophic growth rate enabled to indicate on the presence of virulence mechanisms other than growth rate, for several isolates. Exploration of this direction illustrated variability in resistance to paraquat (associated with resistance to oxidation), which was associated with high and low superoxide dismutase (SOD) gene expression for selected isolates showing high or low paraquat resistance, respectively. Finally, we have used unsupervised learning (clustering analysis) to explore patterns in the multivariable space, which demonstrated two modes of pathogenicity in the tested B. cinerea isolates.     

Pathogenicity variation and DNA polymorphism of Bipolaris sorokiniana infecting winter wheat in the Huanghuai floodplain of China

Wheat root rot, caused by Bipolaris sorokiniana, has led to severe losses of wheat products worldwide. To evaluate the pathogenicity and genetic variation of B. sorokiniana, diseased wheat samples were collected from 97 locations in the Huanghuai floodplain of China in 2014 and 2015 for analysis. A total of 673 isolates were obtained, 262 of which were identified as B. sorokiniana. Pathogenicity analysis of the isolates revealed variation in pathogenicity, which was not directly correlated with geographic region. Large variations in pathogenicity were also found within geographic groups. To determine the genetic structure of the populations, PCR was performed with universal rice primers (URP). Cluster analysis based on amplification patterns showed that the classified groups were correlated with geographical regions. Thus, analysis of the genetic diversity of the population indicated a negative correlation with geographic origin, that is, the greater the distance between sites, the lower the genetic variation similarity coefficient. Identification of wheat germplasm resistance showed that resistant cultivars accounted for a low percentage, while susceptible and highly susceptible cultivars were in the majority. Overall, these results are meaningful for developing strategies to prevent and control wheat root rot.     

基于DYMEX和DIVA-GIS的昆士兰果实蝇潜在地理分布预测

利用DYMEX软件的地点比较和DIVA-GIS软件的BIOCLIM两种模型,分析昆士兰果实蝇Bactrocera tryoni(Froggatt)在中国及全球的潜在地理分布.结果表明,两种模型均能预测出我国33.3～18.2°N、95.8～122.1°E范围内的地区为昆士兰果实蝇的潜在地理分布区,其中,海南、云南、广西、广东、福建、贵州和江西南部、四川东部、重庆西部及台湾部分地区为高度适生区;全球昆士兰果实蝇的潜在分布区主要包括澳大利亚、南亚、南美洲、北美洲南部沿海地区、地中海沿岸部分地区以及非洲中南部地区.     

黄淮麦区小麦全蚀病菌群体的遗传多样性分析

为了解小麦全蚀病病菌的群体组成和遗传多样性,采用8对多态性较好的微卫星标记,对我国黄淮麦区的116个小麦全蚀病菌株进行了分析。8个SSR标记的平均等位基因数为4.25个,多态性信息含量的平均值为0.66。供试菌株的平均有效等位基因数和基因遗传多样性指数分别为1.46和0.27,漯河群体的遗传多样性水平最高,周口群体最低。不同群体间遗传距离均较小,为0.0199~0.1153,其中徐州和周口群体间的遗传距离相对较大,而周口和驻马店群体间的遗传距离相对较小。分子方差分析结果显示,小麦全蚀病菌群体间和群体内均存在着一定的遗传分化,群体间的遗传变异占总变异的10%,群体内遗传变异占90%。6个群体间的基因流为3.5。根据SSR多态性,对来源不同菌株的UPGMA聚类分析结果显示,小麦全蚀病菌群体结构与地理来源有一定的关系。