The Research On Population Genetics And Morphological Variation Of Chinese Wild Pyrus Ussuriensis Maxim

China is one of the center of genetic diversity for pear resources, widespread wild resources.Wild Pyrus ussuriensis Maxim is famous for the extremely cold resistance, rich flavor, high sugar and acid content and the unique aroma. However, due to the climate and anthropogenic reasons, wild P.ussuriensis resources have been seriously damaged, experts predict that if do not adopt appropriate conservation measures, the Chinese wild P.ussuriensis resources will disappear from the earth. This research was studied by SSR molecular marker on11wild P.ussuriensis populations in Inner Mongolia, Heilongjiang, Jilin and other7control populations,in order to reveal genetic characteristics of Chinese wild P.ussuriensis. At the same time,this paper evaluated the morphological characteristic for wild P.ussuriensis resources, to provide a theoretical basis for conservation of China’s wild P. ussuriensis. The main results and conclusions are as follows:1,This study selected20SSR primers which can obtain clear, high polymorphism bonds with good repeatability. Basing on the value of PIC, the order of the effectiveness for the20SSR primers from high to low is as follows:CH04g12, NH206a, CH03d10, NB109a, NB105, NH009, NH029a, NH203a, NB141b, TsuENH155, CH02g01, NH039a, CH03g06, BGA35, CH02b10, CH02d10, CH02e02, EMPc114, CH02b03,NB104a.2,The genetic diversity of20SSR loci for genetic resources shows that the value of na,ne, AR,He,Ho for Chinese wild P.ussuriensis is3.900,2.654,2.856,0.504,0.372; the value of na,ne,AR,He,Ho for Japanese wild P.ussuriensis is5.850,3.765,3.693,0.663,0.573; na, ne, AR, He, Ho for Chinese cultivated pear is7.225,4.696,4.449,0.773,0.573;The value of na,ne,AR,He,Ho for Japanese cultivated pear is44.350,2.788,3.212,0.625,0.423, for P.communis is5.650,3.883,4.048,0.742,0.518, this indicates that the genetic diversity for Chinese wild P.ussuriensis is the lowest compelling with Japanese wild P.ussuriensis,Chinese cultivated pear, Japanese cultivated and pear P.communis.3,The research for20SSR loci of18populations found that:23.76%of genetic differentiation is in the group,76.24%occurred between groups (FST=0.2376, P<0.01). Genetic diversity of P. ussuriensis in inner Mongolia is the lowest in all of the Chinese populations with0.41%gene exchange.The genetic differentiation for5populations in inner Mongolia is the lowest(Fst=0.016-0.041), with the most pure genetic background; Genetic diversity in Heilongjiang and Jilin is higher. The gene flow are14.71%,9.96%respectively, with higher genetic differentiation (Fst=0.029-0.337). Among the11wild P.ussuriensis populations,the genetic diversity for ’HLJ-FY’ were the lowest, the genetic background is the most pure, the gene exchange is only0.15%, but ’HLJ-CL’ has the highest genetic diversity,with the most complex genetic background.The gene exchange for this population reaches42.94%.4,Based on the genetic distance of all the genetic resources,using neighbor-joining clustering method though Mega4software,the18populations can be divided into4groups:group Ⅰ includes5Inner Mongolia wild P.ussuriensis (the genetic distance is0.032-0.104); group Ⅱ consisted of5wild P.ussuriensis in Heilongjiang and1population in Jilin (the genetic distance is0.088-0.322); group Ⅲ is Japanese pear groups including Japanese wild P.ussuriensis pear and Japanese cultivated pears (genetic distance was0.394); Group IV includes Chinese cultivated pear and P.communis (the genetic distance of0.192-0.819).5,Correlation analysis between the morphological characters and SSR markers showed that the gene pool in Inner Mongolia and Heilongjiang is significant or very significant correlated with flower diameter,petal length,petal width,fruit stalk length,fruit length/width,fruit stalk length.Morphological characteristics of the corresponding gene pool in Inner Mongolia is as follows:small flower,short flower stalk,large fruit length/width,short fruit stalk,and the morphological characteristics of the corresponding gene pool in Heilongjiang is as follows:large flowers,long flower stalks,long fruit stalks,small fruit length/width.From the morphological and molecular level we can infer that wild P.ussuriensis in Inner Mongolia and Heilongjiang has significantly genetic difference, may belong to different ecological types.