Studies On Genetic Diversity And Genetic Structure Of Juglans Mandshurica Maxim Natural Population

Inter-simple sequence repeat (ISSR) molecular technique was applied to analyse the genetic diversity and genetic structure of 180 individuals among 6 populations from centralized distributing of Juglans mandshurica Maxim. The results would provide theoretical foundation for effective protection and proper utilization of genetic resources of Juglans mandshurica Maxim and be beneficial to practice.(1) the genomic DNA of winter bud and phloem from Juglans mandshurica Maxim was extracted using the conventional and the modified CTAB method respectively. The results indicated that the modified CTAB method gain clear and repeatable profiles which was the most suitable methods for genomic DNA. The genomic DNA of winter bud and phloem satisficed the request of experiment and solved the problem of season.(2) In order to establish an optimum ISSR-PCR amplification system on Juglans mandshurica Maxim, we carried out a single factor test and Orthogonal design test on the bases of four levels of five factors(Taq DNA polymerase, Mg2+, dNTP, DNA template, primer) respectively.14 primers with rich polymorphism and stable amplification for ISSR were screened. Besides, annealing temperature and cycles were also optimized.(3) 120 polymorphic loci were detected from total 140 loci, the total percentage of polymorphic band(P) was 85.71% using 14 primers selected. At species level Shannon's Information index (â… ) and Nei's gene diversity (h) of Juglans mandshurica Maxim was 0.4521 and 0.3024, respectively.The alleles gene (na) wasl.8571, effective number of alleles was1.5147, it indicated that the genetic diversity at species level relatively high; while at population level, the genetic diversity of LaoYeling was highest and SanHe was lowest.(4) Coefficient of gene differentiation among populations (Gst) was 0.1618 and the majority of genetic variation occurred within populations which accounted for 81.83%.the mean of gene flow (Nm) was 2.5904. Clustering analysis by UPGMA showed the populations that clustered together in genetic was near in geographical, which accord with distributing of physical geography.(5) The genetic diversity of Juglans mandshurica Maxim was high and mainly within the populations, so the mainly reason for preservation of Juglans mandshurica Maxim was because of cutting, habitat destruction and degradation but not genetic variations. The protection strategy should be taken to enhance the habitat protection, avoided from destroying further by mankind, and at the mean time pay more attention to the preservation of indispensably unique populatin in genetic diversity and species.