Genetic Variation Among Different Trunk Types Populations Of Pinus Yunnanensis Franch

Pinus yunnanensis Franch.is a kind of endemic tree species in southwest of China.It is also main commercial tree species.P.yunnanensis can endure not only arid and barren field and it has powerful adaptation for environment,but also it has extremely powerful natural regeneration ability and fast grwoth.P.yunnanensis played an very important role in regional economy and ecosystem.But P.yunnanensis appeared a case that it became recession.There were more and more twisted or crooked unhealthy individuals.The protection of P.yunnanensis superior genetic resources were urgent.At present,there were little research for recession system of P.yunnanensis,and the genetic variation of P.yunnanensis between straight type of trunk and twisted or crooked type of trunk was fewer.Therefore three region(Yiliang,Kunming;Xinping,Yuxi;Lvfeng,Chuxiong)as sampling point in main distribution range of P.yunnanensis were chosed.Needles and cones were collected from every forest stand which were divided into different layers or types of trunk in sampling forest land.Genetic variation and genetic structure were analyzed by phenotypic characters and SSR marker to research the genetic diversity of P.yunnanensis.The main results showed as follows:(1)Genetic variation of the 20 phenotypic traits among 12 populations were analyzed.The result showed that all the 20 phenotypic traits had a wide range of variation both among populations and within populations.Coefficient variation ranged from 7.77 % to 38.97 %.The result of SSR marker showed: observed number of alleles,effective number of alleles,Shannon's information index,observed heterozygosity and percentage of polymorphic bands were 3.983,1.765,0.661,0.358 and 96.1%respectively.All the parameters revealed that P.yunnanensis population was rich in genetic diversity.It showed that the P.yunnanensis could be widely used in genetic improvement.P.yunnanensis could be used as an important tree species for propagation and breeding.The way of combination of populations selection and plus trees selection could better genetic gain.(2)The phenotypic diversity of the 12 P.yunnanensis populations were analyzed.The results showed that the phenotypic differentiation coefficient of needles,cones and seeds were 8.24 %,1.70 % and 6.81 %,respectively.The result of SSR marker showed the genetic differentiation coefficient was 0.012.The average gene flow was 26.938.It showed that genetic variation within populations was the main source.The best way was in situ conservation by the whole protection for superior populations' genetic resources or ex situ conservation by selecting excellent individuals from the superior populations.(3)There were differences both straight population and twisted or crooked population by the analysis of the phenotypic traits and SSR marker,but the differences was slight.Therefore,the different trunk types of P.yunnanensis had a slightly impactin genetic diversity when the stands need to be selected for harvesting.But P.yunnanensis had obvious natural regeneration.Straight plants as mother tree should be kept in order to improve the utilization value of P.yunnanensis forest and economic benefits.