Researches On Seed Nucleus' Variation Of The Ancient Ginkgo Trees In Dabie Mountain Area In Hubei Province

Ginkgo biloba L., belonging to Ginkgoaceae and Ginkgo and endemic to China, isone of the oldest remained tree species in gymnosperm. As Ginkgo trees can live verylong, there are lots of ancient ginkgo trees in China. Dabie Mountain area is one of theimportant distribution regions of ancient Ginkgo trees. In this paper, seed samples werecollected from 113 ancient Ginkgo trees in Dabie Mountain area in Hubei province, andthe variation of ginkgo seed nucleus was studied in three aspects—seed nucleus'characteristics, content of nutritional components and molecular genetic variations, inorder to provide basis for the evaluation, utlization and conservation of germplasmresources of Ginkgo biloba Results are as follows:(1) Seed nucleus' characteristics: There were five types of seed nucleus in DabieMountain in Hubei province, i.e., Changzi, Fozhi, Maling, Meihe and Yuanzi type, andthe Maling type was more than other types. Differences existed in variation of seednucleus' characteristics, whether among or within the regions. The variation of single pitweight was the highest and the variation of the fresh kernel rate was the lowest in all ofthe nucleus characteristics. So single pit weight can be considered as the important indexfor the evaluation of germplasm. The variation within regions was higher than that amongregions. The correlation among seed nucleus' characteristics was very complex. In all ofthe correlations, the correlations among pit weight, length, width, thickness and thatbetween fresh kernel rate and dry kernel rate were high, however, there was no significantcorrelation between fresh kernel rate, dry kernel rate and pit weight, length, width,thickness. Principal component analysis showed that all the characters were simplifiedinto four character group, i.e., pit weight (or length or width or thickness), fresh kernelrate (or dry kernel rate), length/width, thickness/width, which could evaluate seed nucleusand simplified the criterion of evaluation. Clustering analysis showed that individualscould be clustered basically on length/width when they were clustered by seed nucleus'characteristics.(2) Nutritional components: Variations of nutritional components content existedamong and within the Ginkgo regions and the variation within regions was higher thanthat among regions. In twelve kinds of nutritional components (starch, soluble sugar, rawprotein, N, P, K, Ca, Mg, Fe, Mn, Cu, Zn), the variation of starch content was the lowest,and the variations of the content of soluble sugar and mineral were higher than others.Variations of the content of nutritional components was higher than that of seed nucleus'characteristics. There were correlations among nutritional components content and the correlations among starch, soluble sugar and raw protein were higher that among metalmineral nutritional elements, high correlations existed among the elements of Fe, Mn, Cu,Zn. There were no significant correlations between all of the nutritional components andseed nucleus' characteristics.(3) ISSR analysis on genetic variation: Based on the optimum ISSR creationsystem and procedure, polymorphic data of ancient ginkgo trees in Dabie Mountainregion in Hubei province were obtained. 7 ISSR primers produced 87 amplification bands,with an average of 12.43 bands per primer, and the percentage of polymorphic bands(PPB) was 98.85%. At species level, Nei's gene diversity (H_E) was 0.2784, shannon'sinformation index (H_O) was 0.4338. It showed that the ancient ginkgo trees had highgenetic diversity. Analysis on genetic variation within and among populations showedthat genetic differentiation index (ф_ST) was 11.31%, revealing that the genetic variationof ancient Ginkgo trees in Dabie Mountain in Hubei province mainly existed withinpopulations. Molecular cluster results was not exactly consistent with that based on seednucleus' characteristics.