Resource Status And Genetic Diversity Of Picea Brachytyla(Franch.) Pritz.in Jiuzhaigou Valley And Its Conservation Strategy

Based on a comprehensive survey of the current situation of Picea brachytyla(Franch.)Pritz.resources in Jiuzhaigou using line transect method and quadrat method,this paper applied simplified genome sequencing technology to ninety individuals out of six populations,with 26,805 single nucleotide polymorphisms(SNP)identified.Analysis was done to the genetic diversity,phylogenetic,principal component and population genetic structure,which provides the basis for the protection and utilization of P.brachytyla resources.The main results are as follows:1.In Jiuzhaigou area,P.brachytyla are found mainly on the shady slope of acid soil.There are 17 species of undergrowth plants,including fir,spruce,birch,maple,Viburnum and Bashania fangiana.P.brachytyla are mainly natural and mature forests with 400-499 plants per hm2 found at 2200-2600 m a.s.l.in whole Jiuzhaigou area.The forests are at decline phase lacking the ability of natural regeneration.Natural regeneration seedlings were found in only 4 stands.2.Six natural populations of P.brachytyla can be divided into three subgroups POP1,POP2 and POP3 with high,medium and low altitude respectively.TPG and JWC mainly belong to POP1,QZG and YLG mainly belong to POP2,SXC and GGL mainly belong to POP3.SXC population is between POP2 and POP3,whose genetic communication is relatively extensive.The coefficient of genetic differentiation among the six populations was low.3.All the six populations showed low levels of genetic diversity,PIC values above 0.900,which indicate high polymorphism.The individual distribution within the population has a good balance with no significant difference among populations.The natural population of P.brachytyla had a low level of genetic diversity.4.Comprehensive Analysis:the main reasons for the endangerment of P.brachytyla in Jiuzhaigou are poor natural regeneration ability,lack of gene exchange among populations and low genetic diversity.It is suggested to implement in situ conservation at Shenxianchi,Daluxiang and Gonggangling,where P.brachytyla are most found,while creating ex situ germplasm at Shenxianchi to realize the sustainable development and utilization of the genetic resources of P.brachytyla.