Genetic Diversity Analysis Of Salsola Passerina Bunge. Under Different Habitats In Alxa Plateau

Alxa Plateau has the characteristics of desertification,located in the northwest arid region of Inner Mongolia.Salsola passerina Bunge.is a hyperxerophytic semi-shrub with sandstorm resistance and drought tolerance,which is one of the important species in desert areas.Due to the harsh ecological environment in Alxa plateau,the external morphological characteristics,internal physiological structure and genetic characteristics of Salsola passerina have all changed to adapt to the environment.In this study,SSR molecular marker technology was used to analyze the genetic diversity of the Salsola passerina populations collected from 7 different habitats according to wetness gradient in Alxa plateau.In addition,the correlation between environmental factors and genetic characteristics and the impact of environment on their morphology were analyzed by combining the meteorological factors and soil factors of each corresponding sample point.Focusing on the molecular level to study the response of Salsola passerina to the harsh environment,the research conclusions are mainly:1)The correlation analysis between plant morphological charac-teristics and habitat:Average plant crown is 627.77 cm² and average height is 14.73 cm,the differences of plant height and crown amplitude between populations were very significant?P<0.001?.The morphological differentiation is the result of the long-term adaptation of Salsola passerina to the environment,and is also an adaptation strategy to the diverse environment.Correlation analysis shows that there is a significant correlation between the crown of species with annual relative humidity and soil organic matter in 0¹0cm soil layer?P<0.05?.Moreover,the height with soil organic matter in 0¹0cm soil layer have significant correlation?P<0.05?.The PH value of the seven samples is between 7and 10,and the soil is weakly alkaline.2)The SSR genetic diversity of Salsola passerina was analyzed:Salsola passerina has rich genetic diversity.14 SSR primers amplified177 polymorphisms bands and the percentage of polymorphic bands?PPB?was as high as 98.33%.Nei's genetic diversity index and Shannon information index were 0.2507 and 0.3951.The genetic differentiation coefficient(G_ST)at population level was 0.3137 and the gene differentiation index(F_ST)value was 0.3620,and there was a high degree of genetic differentiation between populations,which is the genetic basis for Salsola passerina to adapt to diverse environments and to be widely distributed.The interpopulation gene flow Nm was 1.0939>1,which indicated that the Salsola passerina could maintain the genetic diversity within the population and was not prone to genetic drift.Population 1 and population 2 in regions with good hydrothermal conditions have high genetic diversity,and the genetic diversity of the population decreases with the decrease of wetness gradient.3)The clustering analysis shows that the clusters can be clearly distinguished from each other,showing the form of clustering gradually from east to west in the direction of decreasing wetness gradient.Mantel test results is show that there was no significant correlation between genetic distance and geographic distance.4)Correlation analysis showed that genetic diversity and the environmental factors:Stepwise regression analysis results on number of alleles,Nei's genetic diversity index,Shannon diversity index,percentage of polymorphic loci,the Numbers of polymorphic sites,the effective number of alleles,six genetic diversity index and 0¹0cm of soil organic matter have significant correlation?P<0.05?.This indicates that both soil and meteorological factors have significant effects on the genetic characteristics of Salsola passerina.5)The research results showed that the natural distribution of Salsola passerina in Alxa plateau was characterized by rich genetic diversity and high degree of genetic differentiation,and it could well adapt to different habitats.