Population Genetic Characteristics And Representative Populations’ Phenotypic Traits Of Sophora Moorcroftiana

Sophora moorcroftiana is a perennial leguminous shrub endemic to the Yarlung Zangbo River basin in Tibet which has irreplaceable economical and ecological value.Some studies have found that S.moorcroftiana grow at different geographical locations in the Yarlung Zangbo River Basin have huge differences in phenotype.However,there was are few studies on genetics of S.moorcroftiana in different geographical locations.Researching population genetics of S.moorcroftiana,understanding the driving forces of the genetic structures and the expanding directions and patterns of the species,evaluating the phenotype characteristics of representative populations are particularly important for the development,utilization and subsequent research of S.moorcroftiana.In this study,high-throughput Gentotyping-by-Sequencing was used to perform simplified genome sequencing of 225 individuals from 15 populations of S.moorcroftiana in different geographical locations.A sequence of 2,828.95 M on average was generated from each individual and 2,394,536 single nucleotide polymorphisms(SNPs)were identified in these individuals.The genetic characteristics of each population and subgroup were understood by population genetic diversity assessment,phylogenetic analysis,principal component analysis,and population genetic structure analysis based on filtered SNPs data.In order to In order to explore the association between phenotypic traits and genetic traits of different subgroups,and to select dominant populations with the potential desertification control and introduction,we selected three representative populations,Pop 1,Pop 7 and Pop 15,and made the following observation for these three representative populations.Five seed qualitive traits and seven germination traits of the three representative populations were determined,and multiple comparisons were made to evaluate different subgroups’ seed quality and germination ability.Mild and severe drought stress conditions were set,and the growth index,physiological indexes,chlorophyll fluorescence index and photosynthetic index of the three representative populations were determined.The drought resistance of the three populations were ranked by using the membership function The main results obtained in this study were exhibited as follows:1.15 natural populations could be divided into four subgroups: high altitude Shigatse subgroup,Lhasa and Shannan mixed subgroup,low altitude Linzhi subgroup and Linzhi Gongbu Jiangda subgroup.2.Shigatse has the highest altitude and is located in the upper reaches of the Yarlung Zangbo River,where the gene flow among 6 populations were large and the degree of genetic differentiation were small.There were two populations in the middle reaches of the Yarlung Zangbo River-Pop 7 in Shannan and Pop 8 in Lhasa,of which the locations are between the Shigatse subgroup and the Lhasa and Shannan mixed subgroup,so there were extensive genetic exchanges between pop7,pop8 and the two subgroups they had the genetic information from the two subgroups.The Linzhi populations was located in the lower reaches of the Yarlung Zangbo River basin,with the farthest genetic distance from other subgroups and high levels of differentiation among populations.3.The genetic diversity of S.moorcroftiana populations in the Yarlung Zangbo River Basin was positively correlated with altitude and negatively correlated with longitude.The genetic diversity increased from Linzhi to Shigatse along the elevation gradient,but there were two populations(Pop 7 and Pop 8)in the middle area with the outstanding levels of genetic diversity.4.Through the comprehensive analysis of genetic structure and gene flow and environmental factors,it was found that the seed flow caused by sandstorm is an important driving force for population expansion.5.The representative populations Pop 1 and Pop 7 in the middle and high altitude areas were superior to the low-altitude Linzhi population Pop 15 in drought resistance,seed quality and germination ability.In the mild drought,Pop 1,from Shigatse subgroup,showed the strongest drought resistance ability.In severe drought,Pop 7,from Shannan subgroup,exhibited the strongest drought resistance ability,and exhibited high desertification control and introduction potential.6.The genetic diversity and phenotypic adaptability of S.moorcroftiana populations were consistent in a certain sense,that is,the adaptability to the environment is strong when the genetic diversity is high.Therefore,the utilization and development of S.moorcroftiana in medium and high altitude areas could be comprehensively considered according to their biological characteristics,and the protection for population in Linzhi area could be strengthened.