Genetic diversity and structure analyses of wild and ex-situ conservation populations of Taxus chinensis var. mairei based on ISSR marker.

Genetic diversity and structure of three wild populations(including populations of Huanggang and Huangsha of Jiangxi and Fengxi of Fujian),two cultivated and two derived populations of ex-situ conservation(all located in Nanjing Botanical Garden Mem.Sun Yat-Sen of Jiangsu and Lushan Botanical Garden of Jiangxi) of Taxus chinensis(Pilger) Rehd.var.mairei(Lemee et Levl.) Cheng et L.K.Fu were analyzed and compared by ISSR marker method.The results show that 73 bands are amplified from total genomic DNA of T.chinensis var.mairei with eight primers,in which there are 62 polymorphic bands.Percentage of polymorphic band(PPB),Nei's diversity index(h) and Shannon information index(I) of two ex-situ conservation derived populations are higher,and those of three wild populations are in the middle,but those of two ex-situ conservation cultivated populations are lower.Both of combined ex-situ conservation derived population and wild population have higher genetic diversity,and their PPB,h and I are close with values of 78.08% and 82.19%,0.207 6 and 0.205 8,0.322 9 and 0.325 9,respectively.But there are differences in genetic structure of two populations above,and genetic differentiation coefficient(GST) of ex-situ conservation derived population is 0.068 9,which is obviously lower than that of wild population(0.168 5).Genetic diversity of combined ex-situ conser- vation cultivated population is relatively lower,its PPB,h and I is 60.27%,0.180 7 and 0.275 2,respectively,and its GST is the highest(0.251 4),which is obviously higher than those of combined wild population and ex-situ conservation derived population.It is concluded that under conditions of secondary forest environment in botanical garden,genetic diversity of ex-situ conservation derived population of T.chinensis var.mairei returning to natural habitat tends to be abundant and is close to that of wild population,thus,it is proved that botanical garden has the huge potential in ex-situ conservation of endangered plants,which was never known in the past.