Population Genetic Diversity Analysis Of Puccinia Triticina In Hebei、Shandong、Sichuan And Xinjiang Provincs Based On EST-SSR

Wheat leaf rust caused by Puccinia triticina is one important epidemic disease thatthreat to the safety of wheat production. The mutations and toxicity structure of Pucciniatriticina often leads to loss resistance to leaf rust of wheat varieties. Studying thepopulation genetic structure of P. triticina produced understanding genetic variability of P.triticina populations, and was also very important for the deployment of resistant cultivarsand disease control. In this study, all the P. triticina samples collected from Hebei,Shandong, Sichuan and Xinjiang provinces were analyzed by EST-SSR marker to researchthe molecular genetic diversity. The main results were as follows:1. Total217Single uredinial isolates were isolated from the collections and tested forvirulence phenotype on near-isogenic lines and other lines with known leaf rust (Lr)resistance genes. Dendrogram analysis showed that there was high virulence similarityamong different regions, and similarity coefficients were0.65-1.00. There was nosignificant correlation between virulence phenotype and isolates origin.2.217uredinial isolates were analyzed with21EST-SSR markers,18of them couldproduce steady and clear polymorphic bands. Dendrogram analysis showed that geneticsimilarity coefficients were0.62-1.00, genetic polymorphisms had some correlation withisolates origin. The isolates from same region had the same genotype, which demonstratedcorrelation between genetic polymorphisms and isolates origin, the isolates from differentregion had the same genotype, which demonstrated the gene flow among the regions. Thecorrelation between genetic polymorphisms and isolates origin higher than virulencepolymorphisms.3. The Nei’s gene diversity （H） of virulence polymorphisms and molecularpolymorphisms was0.31and0.35. Showed that genetic differences of molecular markersrevealed higher than virulence polymorphisms. The MXCOMP module in NTSYS-pc2.10ewas used to analyze the relationship between virulence and EST-SSR marker, indicatedthat there were not relative completely with the correlation coefficient of0.08. Twodimensional plot of principal coordinates analysis have the same result. 4. The four virulence phenotypes with high frequency including101isolates wereanalyzed for their molecular polymorphisms and virulence polymorphisms. Virulencephenotypes and molecular polymorphisms had high level of genetic diversity. Virulencephenotypes had no relationship with SSR genotypes. Different virulence and differentgenotypes might be present in the same pathotype. The same or near genotypes might bepresent in the different pathotype.5. Genetic analysis was conducted by POPGENE version1.32based on EST-SSRdatas, showed that there were genetic differentiation between and among populations (Gst=0.15, Dst=0.05). Genetic differentiation was investigated by AMOVA, the resultsshowed that there were about74.97%of the total variations within populations. The maingenetic variation came from the same population. The Nm was2.82, indicating thatmigration of pathogen among the regions was presented.6. Genetic differentiation analysis by POPGENE version1.32with the four popu-lations showed that the populations of Puccinia triticina were considerably genetic diver-sified at the higher molecular level. The Genetic diversity parameters of Hebei was themost complex（H=0.36，I=0.52）. The result showed that the genetic distance (D) was0.0686-0.1524, similarity coefficient of four groups was0.8587-0.9337, indicating a closerrelationship between the four groups. Hebei and Shandong have the recent genetic distance,showed the the highest genetic similarity was Hebei and Shandong, the lowest geneticsimilarity is Xinjiang and Shandong, the Similarity coefficient is0.8587. UPGMA clusteranalysis showed that4populations were clustered into3groups at similarity coefficient0.91, Hebei and Shandong clustered in group1, Sichuan clustered in group2, Xinjiangclustered in group3, and the closest genetic relationships were found between Hebei andShandong, indicating that there was high genetic similarity among regions, and the geneticrelationships were associated with geographical distribution.