Genetic Diversity And Population Structure Of Endangered Ottelia Acuminata Var. Crispa

Ottelia acuminata var. crispa is a variant belong to Hydrocharitaceae, currently only exist in Lugu Lake in Yunnan Province. O. acuminata var. crispa is a submerged dioecious plant, water environment, climatic conditions, nutrient often been a factor to it and now has been an endangered species. Ottelia acuminata was classified in the IUCN Red list as critically endangered species in 2004. Except Ottelia acuminata var.crispa, the other varieties are mainly distributed in Guizhou, Yunnan, Guangxi and other places. Empirical study of Ottelia acuminata research has focused on the morphology,geographical distribution evolution, seed storage and germination, and these studies are usually years old. For O. acuminata var. crispa, genetic diversity of this rare species is seldom reported. Researches on the genetic diversity of O.acuminata var. crispa and puts forward the protection strategy becomes meaningful since the environment devastation. Therefore, our study use Ottelia acuminata var.crispa as the main material, using molecular marker technology to study the genetic diversity and population structure, illustrate the relationship between three species belong to Ottelia Pers., discuss the reasonable conservation strategies. The main results are as follows:1. We established AFLP reaction systems suites for O. acuminata var. crispa.DNA extraction was applied by genomic extraction kit(TINGEN), 100 ng DNA was preferred for our digestion and ligation. Digestion reaction was reacted at 4centigrade overnight, ligation reaction was at 37 centigrade for 1.5 hour. 10 fold dilution of digestion and ligation products was used as templates for Pre-PCR,also 10 fold dilution of Pre-PCR products was applied to selective PCR.2. We analyzed the genetic diversity and population structure of O. acuminata var. crispa distributed in Lugu Lake located in Yunnan province. 64 primer pairs was selected for experiment, finally 3 pairs of polymorphic, with clear bands were selected in our study. Using 3 fluorescence primer pairs, 138 bands were obtained from 11 populations of which 61 was polymorphic, percentage of polymorphic bands was 44.20%, indicated O. acuminata var. crispa maintained a low level of genetic diversity. Mean Nei’s genetic variance index HE was 0.1380(SD 0.1892), Shannon’sinformation index I was 0.2079(SD 0.2783). Gene flow of O. acuminata var. crispa was 0.3148, indicated a low level of gene flow between O. acuminata var. crispa populations. STRUCTURE analysis divided 11 populations into 2 groups, AMOVA analysis suggested 64% genetic variance between populations and 36% genetic variance within populations.3. Genetic relationship analysis indicated Ottelia acuminata var. songmingensis and Ottelia acuminata(Geghep.) Dandy maintained a close relation, Ottelia acuminata var. crispa and Ottelia acuminata var. songmingensis maintained a far relationship.4. Mantel test showed no apparently correlation between geographic and genetic distance. Therefore, besides in-situ protection, we suggestions ex-situ protections should be carefully investigated. A thoroughly sampled strategy was plausible and individuals from different populations was separated carefully to reduce genetic erosion.