Genetic Diversity And Specific DNA Fragments Conversion Of Melampsora Larici-populina

Melampsora larici-populina(MLP),a heteroecious fungus caused serious damage and spread widely around the world.In China,it mainly distributed across the northwest to northern,and infects various poplars,such as Sect.Tacamachacae,Sect.Aigerios and their hybrids poplars.Melampsora larici-populina can reproduce and be dispersed rapidly with huge population and high pathogenic mutation frequency.In order to further investigate the genetic evolution of the strains,63 collections from 11 population in China were analyzed by SSR molecular marker technique.The following results were obtained:(1)10 out of 27 selected primer pairs were screened out,with which 98 alleles were detected in 63 MLP strains,including 13 alleles detected by primer MLP4,MLP12 and MLP43,and 6 alleles detected by MLP57.The average number of alleles(Na)was 9.8000,and the effective number(Ne)was 5.9878.The MLP strains showed higher genetic diversities and rich genotypes.The observed average heterozygosity of all strains was 0.4109,significantly less than the expected heterozygosity of 0.8267,7 inbreeding coefficient values are positive within the amplicons from10 primer pairs in this study,indicating that there are less hybrids within the parental population and more homozygote.(2)The average genetic differentiation coefficient(Fst)was 0.3505 between the 11 MLP populations,indicating that he level of genetic differentiation is generally high,and the genotypes among groups are diverse.The average gene flow is 0.4634.Among them,gene flows of 8 loci(Nm)are less than <1,indicating that the gene flow is partially obstructed.In different regions,the genetic diversity of MLP flora is different.The lowest Shannon’s diversity index(I)is 0.2971 in Jiangsu(Pop11),and the highest is 1.7332 in Huoditang area of Qinling(Pop3)。(3)The UPGMA phylogenetic tree was constructed which was based on the Nei’s genetic distance.11 populations were divided into 6 groups.And the population of Qinling is the base population of other geographical groups.UPGMA clustering of 63 strains showed that MLP population differentiation was associated with the geographic origin of the strain.The Guanzhong Plain population may be from the Tiantai Mountain,and the Sichuan population may be from the Qinling HouZhenzi,and the complex differentiation of the remaining population may be related to the transportation of poplar seedlings,but both are related to the Qinling strain.(4)This study screened and cloned the specific DNA fragments of Guanzhong population in Shaanxi(Group5)and Huoditang population in Qinling(Group6),then transformed them into codominant markers and detected the sensitivity.And the minimum concentration of DNA detected was 5 ng/L.This study laid the foundation for distinguishing the two floras and monitoring the distribution,variation and epidemic characteristics of the floras in the area.