Genetic Diversity And Phylogeny Of Salix Psammophila Based On TrnL-F And TrnD-T Sequence

Salix psammophila is an important tree species for wind and sand fixation and vegetation restoration in northwestern China.It has important ecological and production application values,and is mainly distributed in the Mu Us Sandy land and Kubuqi desert.In this paper,16 populations of 339 individuals in the National Germplasm Resource Bank of S.psammophlia were used as experimental materials.The sequences of the chloroplast non-coding regions trnL-F and trnD-T were sequenced,and haplotypes were obtained by analyzing chloroplast DNA sequence variations Types,calculating the genetic diversity and genetic structure of the populations of S.psammophila,inferring the genetic relationships between haplotypes,and exploring the dynamic history of populations.The main results are as follows:(1)The sequence of trnL-F in the chloroplast non-coding region of S.psammophila was obtained with a length of 965 bp and 6 mutation sites.Nine haplotypes were found with a haplotype diversity of 0.645 and nucleotide diversity of 0.00091;The trnD-T sequence is 846 bp long,with 6 variant sites and 6 haplotypes.The haplotype diversity and nucleotide diversity are 0.530 and 0.00013 respectively;the combined sequence of trnL-F and trnD-T is 1811 bp,there are 12 mutation sites and 16 haplotypes.The haplotype diversity and nucleotide diversity are 0.737 and 0.00107,respectively.(2)S.psammophila has higher genetic diversity(trnL-F:HT=0.650,Hs=0.603;trnD-T:HT=0.530,Hs=0.488;combine:HT=0.742,Hs=0.700),the total genetic diversity of the population was higher than the genetic diversity within the population.AMOVA analysis showed that S.psammophila,mainly occurred within the population(trnL-F:90.67%;trnD-T:91.57%;combine:91.16%).The genetic differentiation among the populations of S.psammophila was very small(trnL-F:GST=0.072;trnD-T:GST=0.079;combine:GST=0.0565).(3)The chloroplast gene haplotype network diagram of S.psammophila shows radioactive distribution,haplotypes L3(trnL-F:L3=191),D3(trnD-T:D3=226),H3(combine:H3=163)are located in the center of their respective network maps,and are the original haplotype and dominant haplotype of S.psammophila.The grouping of haplotype network graphs is consistent with the grouping of phylogenetic trees.(4)Permut calculation results based on cpDNA non-coding regions(trnL-F and trnD-T)data show that no single sequence or combine sequence has a phylogeographic structure;Mantel test results show that the genetic distance between populations no significant correlation with geographic distance(trnL-F:r=-0.55544,P=1;trnD-T:r=0.20699,P=0.171;combine:r=-0.31712,P=0.951);neutral test and mismatch analysis shows that S.psammophlia has not expanded recently.