The Genetic Diversity And Phylogeography Of Litsea Auriculata, An Endemic And Rare Plant In China

Litsea auriculata Chien et Cheng is a deciduous plant, Which is also rare and endemic to China, mainly distributed in mixed forests,500-1000 meters above sea level, of Zhejiang, Henan and Anhui provinces. Identifying this plant is easy because of the deer plaques after small bark flakes peeling, as well as its leaves, petioles, fruit cups. The wood is density, perfect for furniture, and fruits and roots have medicinal value.In these years, most researches in Litsea auriculata Chien et Cheng focus on breeding technology and chemical compounds, but no one aims at studying its genetic diversity. Using SSR molecular markers,231 individual plants from 8 natural populations were analyzed to explore its genetic diversity and structure. According to the geographical distribution of cpSSR haplotypes detected in Litsea auriculata Chien et Cheng, the author made a brief analysis in phylogeography. This research aims to provide theoretical basis for making scientific protection strategies.15 primer pairs are used in this experiment, containing 8 nuclear primer pairs screening from relative species’ and 7 cpSSR markers screening from consensus chloroplasts primer pairs. The main results are as follows:1、The genetic diversity of Litsea auriculata Chien et Cheng above the species level was 0.515, and the haplotype diversity was 0.1673. Inbreeding was relatively serious within all populations,so there existed too much homozygous form. The test for Hardy-Weinberg equilibrium showed that vast majority populations deviated from the equilibrium. Linkage disequilibrium test also indicated that inbreeding among individuals within groups was serious, and high level of chromosome restructuring existed.2、STRUCTURE analysis and Principal coordinates analysis exhibited that two clusters existed among the 8 populations. Cluster 1 and cluster 2 contain three (HX, AS,AY) and five (ZQ, ZD, ZT, HJ, HY) populations respectively. The redult of UPGMA cluster analysis also supported the above classification. Both nSSR and cpSSR research showed that more than 70% Litsea auriculata Chien et Cheng total genetic variation occurred within the populations.3、Analyzing the distribution of all 28 haploid types, we deduced that Dabie Moutain and Daming Moutain were two major glaciation shelters of this plant,and other three populations (HY,ZQ,HX) only retained limited individuals during glacier period. Then,in the interglacial period, Litsea auriculata Chien et Cheng spread outward from the Dabie Moutain and Daming Moutain.4、We inferred that ecological factors,including habitat destruction and fragmentation,deforestation,insect pest and so on, were the main reasons for Litsea auriculata Chien et Cheng becoming endangered. But it should be also noted that the genetic diversity mainly existed among the natural populations, and the gene flow was very low.