Molecular Identification And Genetic Analysis Of Wild Taraxacum Kok-saghyz From Xinjiang

Russian dandelion(Taraxacum kok-saghyz,TKS)is a perennial dandelion herb in composite family.Its root can produce natural rubber,also known as rubber dandelion.It is an important substitute resource for rubber production and a model plant for rubber production research.T.brevicorniculatum(TB)and T.officinale(TO)are two dandelion species widely occurring in the locations of wild TKS.The morphology of these three dandelion species is similar in seedling stage,which affects the collection and evaluation of TKS germplasm resources and future large scale commercial planting.In addition,there was no study of population structure of TKS wild germplasm from in Xinjiang Tianshan Valley bordering China and Kazakstan.This molecular identification and population structure study of TKS wild germplasm resources in Xinjiang were respectively conducted by using DNA barcoding and SSR molecular markers.The main work contents and research results are as follows:1.Using 10 TKS,2 TB and 2 TO wild resources as materials,four DNA barcodes,including three chloroplast DNA(trn H-psb A,pet L and ycf1)and one nuclear DNA(ITS2)sequences,were screened.It was found that ITS2 and trn H-psb A sequences showed significant interspecific variation.In ITS2,a total of 12 interspecific variation sites at 30,43,44,73,95,158,166,176,197,202,208 and 211 could effectively distinguish TKS,TB and TO.2.Using ITS2 sequences,we constructed phylogenetic trees of 39 TKS,10 TB and 11 TO.We found that all TKS sequences and some TB sequences were clustered into a large group,while other TB sequences were clustered into groups of different sizes either alone or with TO sequences.At the same time,it was found that ITS2 could’t cluster TKS resources according to the geographical distribution of sampling,but could cluster TB resources according to the geographical distribution of sampling.3.Using SSR analysis of 11 pairs of primers,the population structure and genetic diversity of 48 wild TKS from Xiaaksu and Xiata regions in Zhaosu County,Xinjiang were studied.The results showed that the heterozygosity of TKS in Xiaaksu area was higher than that in Xiata area,and the principal coordinate analysis showed that most of the samples could be divided into two clusters according to the geographical distribution,while a few samples could’t be classified,and the population structure of TKS was relatively low.4.The rubber was extracted from the dry roots of 6 wild TKS in Xiaoksu and Xiata areas by acid-alkali boiling method,and the molecular weight of rubber was measured.The results showed that the rubber content of TKS in the two regions was similar,which was about 10.2% of the root dry weight.The rubber molecular weight of TKS in two regions(Mw = 1,390 k Da;Mn = 832 k Da)was similar to that of rubber tree rubber,and the molecular weight of Xiata was higher than that of Xiaoaksu...