Strobile Quantity Investigation And Genetic Diversity Of Microsatellites (SSRs) For 1.5 Generation Clonal Seed Orchard Of Masson's Pine(Pinus Massoniana L.)

A clonal seed orchard of masson's pine in Maanshan Forestry Farm, Guizhou Province was studied by microsatellite (SSR) markers. And the strobile quantity, the relationship between ratio of female to male strobile and ratio of fruiting was also analyzed. Comparison of the genetic diversity among the improvement course of masson's pine was made and the influence of pollination toward filial genetic diversity, and then discussed the strategies to manage seed orchards. The results were as follows:1. Vertical distribution of the strobile in the crown was a typical stratiform distribution pattern. About 89% male strobile were in the middle and bottom stratum while 80% female strobile were in the top and middle canopy. There were signiffieant differences in production of female and male strobile among clones. There were great differences in the ratio of female to male strobile among clones and this was quite constant over time .The difference of strobile quantity may influte genetic composition of filial generations. There was still a"relative lack of pollen"for seed orchards in pollinating period. The dominance of male or female strobili of a few clone in seed orchard made it possible for genetic base of seed orchard's seeds to become narrower.2. Ten polymorphic SSR primers were selected from 205 primers developed in P.massoniana, P. taeda, P. radiate, P. sylvestris, P. cembra, et al. The number of alleles per locus varied from 4 to 5, and the total polymorphic alleles in all loci were 42 and 4.2 on average.3. Parentage and the progeny population showed a high genetic diversity. The analysis compared between the progeny and parentage populations showed that: the mean alleles, the effective number of alleles (Ne), the Shannon's diversity index (I), mean observed heterozygosity (Ho) and the gene flow (Nm) of progeny which were 4.2, 3.1773, 1.2365, 0.9901, and 7.3444, were all higher than the parentage's 4.1667, 3.0371, 1.1674, 0.9667 and 3.0302 respectively, expect mean expected heterozygosity (He), the Nei diversity (Nei)of progeny (0.6758,0.6755) which was little lower than the parentage's 0.6999,0.6882. Those all showed relatively high level of gene flow among families and minished the genetic differentiation between families, meant that the progenies of this seed orchard keeped a higher level of genetic diversity.4. The analysis of the genetic distance of the progeny and parentage populations showed that the parents had a little influence on the progeny population, the result showed that the genetic distance of all the families of the progeny population had some difference with that of the parentage. It concluded that the collocation of single tree of every family was reasonable, which basically avoid the inbreeding depression.