Population Genetic Structure Of Chinese Puccinia Triticina Based On Multi-locus Sequence

Wheat leaf rust, caused by Puccinia triticina, was a significant disease in wheat which is widespreadand occurs in the growing areas of wheat in China, and seriously affect the yield of wheat. Thus, it issignificant to know the genetic structure of virulence and molecular phylogeny so as to understand thevariation pattern which could help to control wheat leaf rust. In this study,76Puccinia triticina isolateswere collected from Yunnan, Sichuan, Gansu and Henan in2012.31differential hosts were used toanalysis the virulence of P. triticina in seeding stage and four partial genes EF-1α（1227bp）, GAPDH（1289bp），TUB（1198bp） and RPB2（711bp） were used to analysis the moelcular genetic structureof P. triticina. The results help to1. understand the virulence structure of P. triticinaFourty one pathotypes were identified mainly including SHJ(9.2%)、THT(7.9%)、SHF(5.3%)、PHT(5.3%)、THP(3.9%)、THF(3.9%)�'�THK(3.9%). Virulence frequency to Lr2b, Lr2c, Lr10, Lr14a,Lr14b and Lr33were above75%in all the four populations, indicating the lost of resistance of thesegenes. Virulence frequency to Lr9, Lr19, Lr24, Lr25, Lr28, Lr29, Lr38and Lr42were lower than30%in all the four populations showing the effective of the resistance genes. Lr2a, Lr3, Lr11, Lr18, Lr20,Lr27+31and Lr36were variable in the four populations for the virulence frequency which variedgreater than50%. The result showed that the virulence diversity in Sichuan and Yunnan were higher,followed by Gansu and Henan. UPGMA dendrogram showed the virulence in Yunnan, Sichuan andGansu were similar, and were different from Gansu population.2. understand the molecular genetic polymorphisms of the four populationsThe total length of the four sequences was4425bp in which12variation locus were found, one wastransition and11were transversion, they were all parsimony-informative site. In total,32haplotypeswere detected. Out of the32haplotypes, there were11haplotype found in Yunnan population,12inSichuan,12in Henan and13in Gansu population. The high haplotype diversity and low nucleotidediversity in the four populations indicating the expansion of P.triticina.3. understand the genetic differentiation and gene flow among populationsThe results of Fst showed insignificant genetic difference in Sichuan-Yunnan and Gansu-Henan,while Yunnan-Gansu, Yunnan-Henan, Sichuan-Gansu and Sichuan-Henan existed a significantdifference. Gene flow existed in all the four populations and the gene flow were frequent in Yunnan-Sicuan and Gansu-Henan while Nm were below1between any other two populations expalining thebarrier between these populations.4. make the genetic structure and evolution of P. triticina clearNeighbor-joining(NJ) tree and STRUCTURE2.3.4divided the76P.triticina into two clusters.AMOVA analysis clarified the main variation of P. triticina was within population. Network ofhaplotypes indicated most of Yunnan and Sichuan haplotypes were ancient haplotypes and most ofGansu and Henan haplotypes were young Neutrality tests showed Tajima’s D, Fu’s and Li’s D and Fu’sand Li’s F were not significant indicating that the evolution of P. triticina populations was according with neutral theory and population expansion was testified in the four P. triticina populations for thesignificant value of Fu’s Fs.