Analysis On Genetic Basis Of Excellent Trees Of Ginkgo Biloba

Ginkgo biloba is the only living species in Ginkgoaceae and an important forest tree species. In this paper, by applying morphological markers and ISSR molecular markers, researches on genetic variation of30excellent trees in Suizhou and Anlu in Hubei Province were carried out to analysis the genetic basis of these trees, in order to provide references for ginkgo germplasm evaluation, protection and utilization. Main results were as follows:(1) The30excellent trees belong to four types according to the seed nucleus type index:25trees belong to Meihe type,3trees belong to Maling type;1tree (SZ515) belongs to Fozhi type;1tree (SZ601) belongs to Yuanzi type. Meihe types accounted for83.3%of the total.(2) The trees with the widest genetic basis and the narrowest genetic basis was AL211and AL212in respective, according to comprehensive order based on variation degree of6quantitative traits (length, width, thickness, karyotype index, thickness ratio, single grain weight).(3) Differences of the6quantitative traits among the30excellent trees vary in different extent, of which the largest was single seed nucleus weight and the minimal was kernel rate. Variance analysis showed that differences of the six traits among30trees were all extremely significant. Meanwhile, the single seed nucleus weight had extremely significant correlation with length, width and thickness of the seed nucleus.(4) ISSR analysis on endosperm DNA samples of the30ginkgo trees was carried out using12ISSR primers. Results showed that these ginkgo trees had high heterozygosity, which was between31.37%and47.55%, and the average was41.44%.(5) Genetic diversity of the30trees was different according to the analysis with POPGEN32software. PPL was between30.83%and44.72%; Na was between1.2083and1.2372; Ne was between1.1416and1.2533; H was between0.0810and0.1427; I was between0.1191and0.2074. The genetic differentiation analysis showed that the variation within the trees is greater than among the trees. Comprehensive order based on the above five parameters suggested that the genetic basis of SZ510was the widest and that of SZ502was the narrowest.(6) Genetic diversity analysis of the30trees showed that at totality level, PPL was99.07%, Na was1.9907, Ne was1.3025, H was0.1934, I was0.3144, which indicating that these30trees in totality has high genetic diversity and wide genetic basis. Differences in genetic variation existed among the four seed nucleus types. Analysis of genetic differentiation indicated that the genetic variation within types was larger than that among types.(7) Genetic identity of the30trees based on haploid data ranged from0.8314to0.9782; and that based on diploid data ranged from0.6111to0.9306. Cluster results based on haploid data and diploid data were not totally the same.