Biological Characteristics And Population Genetic Diversities Of Bipolaris Maydis In Anhui Province

Maize is one of the world's three major food crops in food security,which occupy a very important position,and the plant amount is ranked only second to wheat,rice.Corn southern leaf blight is the important diseases on the production of corn.It can cause huge losses on corn.This research collected samples of corn southern leaf blight from Fu Fang,Chu Zhou,Su Zhou,Lu An,Beng Bu,Huai Bei,Bo Zhou and He Fei eight major corn producing areas in Anhui Province.And 234 strains were identified as Bipolaria maydis by morphologic characters.The study assessed 234 strains and compared the biological characteristics and studied population genetic diversity analysis of Bipolaris maydis by ISSR technology.The results of the study were as follow:1.There were 234 strains of Bipolaria maydis isolated by using tissue isolation and single spore isolation from Fu Yang,Chu Zhou,Su Zhou,Lu An,Beng Bu,Huai Bei,Bo Zhou and He Fei eight major corn producing areas in Anhui Province,and they were identified as Bipolaria maydis.2.The comparison of biological behaviour of 234 strains of Bipolaria maydis from the same region and the different regions shown that mycelia growth ? conidia production ?colony colour and spore dimension all had obvious difference.3.Through comparing the different reaction conditions,the optimal ISSR-PCR reaction system was established.From 40 random primers,11 primers were selected,which showed clear hands,and good polymorphic,stability and repetition.It indicated that some repetitive sequence similarly to these primers were widespread in Bipolaria maydis.4.There were 137 polymorphic bands amplified by ISSR,of which 109(79.56%)were polymorphic.The results showed that these strains existed a high degree of genetic diversity in Anhui Province.5.According to the clustering analysis of ISSR,this research did data analysis by NTSYSPC.The strains from the same geographic region were distributed in different groups.And the average similarity coefficient of 234 strains with other ones was between 0.69 ~0.96.when 234 strains are classified as hefei,huaibei,suzhou,chuzhou,luan,bengbu and bozhou,fuyang eight geographic populations,the results showed that the average similarity coefficient was 0.92 ~ 0.97 among geographic populations.The genetic similarity coefficient between the chuzhou and hefei was highest.The results initially determined that the genetic diversity of Bipolaria maydis had certain relationship with geographical origin.6.The correlativity among mycelia growth,conidia production,pathogenic virulence,and genetic make-ups of 60 strains were analyzed by the statistical methods of MantelHanzel.It turned out that there was correlation among mycelia growth,conidia production and pathogenic virulence.The correlation between mycelia growth and conidia production was highly significantly inverse.The correlation between pathogenic virulence and conidia production was strong inverse,and there was the positive correlation between mycelia growth and pathogenic virulence.But they all had no correlation between genetic make-ups and the biological characteristics.7.The POPGENE analysis software showed that the ratio of the polymorphic loci(PPL)was 81.75%.The index of gene flow(Nm)was 2.8468.The average Shannon index(I)was 0.4320.It may result from some gene flow among populations;the population had a high level of genetic diversity.The general Nei's genetic diversity index was 0.2876,and the genetic diversity index in the population was 0.2438.The Nei's coefficient gene differentiation was 0.1494.The genetic variation come mainly from within the population,and the source of variation among populations was relatively little.