Polymorphic Analysis On The Key Genes Of Saponins And The Construction On Core Collection Of Psammosilene Tunicoides

Psammosilene tunicoides W.C.Wu et C.Y.Wu (Caryophyllaceae) is an endemicherb species in Southwest China, and mainly distributed in the Hengduan Mountainsregions, with some sporadic distribution in the northwest Guizhou, the central andsouthern Yunnan. the key enzyme genes (squalene synthase gene and β-amyrinsynthase gene) in the synthesis of triterpene saponins from P. tunicoides wasamplified and screened in11representative populations of P. tunicoides in order toanalyze its genetic diversity, genetic differentiation and spatial distribution patternsbased on the method of phylogeography, moreover, to explore the method to constructcore collections of the species. This research is significant to utilization,germplasmselection and resource protection of P. tunicoides. The main findings and conclusionsare summarized as follows.1. The β-amyrin synthase gene (β-AS gene) could be used as a potential nucleargenetic marker on phylogenetic and phylogeographic analyses for P. tunicoidesand other related genera of Caryophyllaceae.2. It was found that common haplotypes had a wild distribution and the rarehaplotypes distributed in one population or adjacent areas. The genetic spatialdistribution pattern of P. tunicoides which might be related to the complicatedtopography and strong environmental heterogeneity of this hotspot region, whichlikely limited seed and pollen flow, and resulted in differentiation on the geneflow and genetics among populations.3. Both exons and introns of the β-AS gene consistently revealed a high level ofgenetic diversity at the species level with a strong phylogeographic structure in P.tunicoides. Two major genotypes were detected in exons, while four in introns.The evolutionary trend of exons and introns was consistent. 4. The haplotypes were classified into three grades (unique haplotypes, rarehaplotypes and common haplotypes) according to the frequence and geographicdistribution. According to the rule of core collection, the areas containing uniquehaplotypes (Hap9), rare haplotypes (Hap3), both unique and rare haplotypes(Hap7) should be given special attention, as to other common haplotypes, it isbetter to protect as many populations as possible. The result of this study revealsthat the exons of the β-AS gene is a reliable genetic marker used to core collectionof P. tunicoides.