Genetic Diversity And Population Structure Of The Endangered Species Ulmus Lamellosa

Ulmus lamellosa is endemic to China and few in number which ma-inly distributed in the North China area.And it is one of the precious g-ermplasm resources ulmaceae plant in our country.Total of16popul-ations of U. lamellosa were sampled from Shanxi Province,Hebei Pro-vince,Henan Province,Beijing and the Nei Monggol Autonomous Regi-on.This study was condueted by208individuals of16populations todetermine genetic variation,the present situation and the law of gen-etic differentiation to provide us the theoretical basis and basic datafor germplasm conservation and genetic improvement.The main resu-lts as following:(1)Morphological diversity among/within populations were discus-sed on the basis of16phenotypic traits analysis.Traits such as the le-af shape,petiole width and leaf thickness etc showed a trend of dicli-ne,upon increasing of the latitude.There existed correlations amongthe morphological characters mentioned above.According to the variation coefficient,indexs of the leaf vein,tooth of the widest partand the blade were more stable.The results of variable coefficientand Shannon diversity index showed that phenotypic variationshowed a trend of dicline upon increasing of the latitude. The mean p-henotypic differentiation coffieient(VST) showed that the variation am-ong populations(27.29%) was less than that within population.Accord-ing to the correlation analysis,the populations of U. Lamellosa invest-igated may be divided into three groups.(2)The SRAP system was built and used for the amplification reac-tion in the experiment.There were totally88primers were selected a-nd analyzed by amplifications using11pairs of SRAP primers screene-d.The bands amplified by each primer combination were17.7,whichranged from13to21.SRAP molecular marker showed that genetic di-versity at population level was higher than species level.Genetic di-versity was observed at population levels with the proportion of pol-ymorphic loci(PPB) varying from31.44%to57.73%(average44.46%),the observed allelic number(na) ranging from1.314to1.577(avera-ge1.451),the effective number of alleles(ne) ranging from1.203to1.268(average1.236),and the Shannon index information(I) ranging f-rom0.171to0.244(average0.214),and the Nei diversity index rangi-ng from0.116to0.156(average0.141).At species level,the geneticdiversity(PPB=82.72%;na=1.747;ne=1.3329;I=0.3583;h=0.221)showe- d a low level of genetic diversity.There was the relatively high levelof DNA genetic diversity in Shanxi(populations of CC,SGS,XTS,QLY)and Henan (populations of HLS,BYS), and the relatively low level ofgenetic diversity in Hebei (populations of TGS) and Nei Monggol(populations of MLG,JFS,NBG) among16populations based on inte-gration estimated.The level genetic differentiation coefficient (Gst=0.3696) among populations meant there was63.04%genetic differenti-ation within population,with a low level of gene flow(Nm=0.8528).Thegenetic distance was significantly correlated with the geographicaldistance between populations,according to the UPGMA cluster analy-sis and Mantel test.SSR molecular marker showed a low level of genetic diversity atpopulation levels with the average observed allelic number of allele-s per locus(na=2.9286),the effective number of alleles(ne) rangingfrom1.2647to4.5714(average2.5319),and the expected heterozyg-osity(He) ranging from0.2106to0.7862(average0.5683),and theobserved heterozygosity(Ho) ranging from0.2125to0.9375.The gen-etic diversity was observed at population levels with the observedallelic number(na) ranging from1.6429to1.9286(average1.8080),t-he effective number of alleles(ne) ranging from1.6016to1.8420(av-erage1.7245),and the expected heterozygosity (He) ranging from0.3302to0.4476(average0.4027),and the observed heterrozygosity(H o) ranging from0.5571to0.7429(average0.6509).There were the hi-ghest level of DNA genetic diversity in Henan(populations of BYS,HLS) and Shanxi(populations of MS,CC,DH,XTS),and the lowest level o-f genetic diversity in Hebei(populations of TGS) and Nei Monggol(p-opulations of JFS) among16populations.The level of genes heteroz-ygosity ratio varied degrees(Fst=0.3531) among populations demons-trated that there was a greatly genetic differentiation within populat-ion,which may result from low level of gene flow(Nm=0.6489).The ge-netic distance was significantly correlated with the geographical dis-tance between populations,according to the Mantel test.SSR and SRAP molecular marker showed a low level of genetic d-iversity was observed at U. lamellosa.And there was a greatly genet-ic differentiation within population.