AFLP Analysis On Genetic Diversity Of Larix Principis-rupprechtii Mayr. In Shanxi

Prince Rupprecht's larch (Larix principis-rupprechtii Mayr.), one of cold temperate coniferous trees in north China, is important for soil improvement and water conservation. The natural forest of this species is distributed mainly in Hebei and Shanxi with the elevation ranged from 1500m to 2700m. The object of this study is to estimate genetic diversity and spatial genetic structure characteristics of six natural populations of L. principis-rupprechtii in Shanxi Province by AFLP. The main results are as follows:1) AFLP reaction system and procedures was established. The influencing factors (the time of DNA digestion, the amount of endonucleases EcoR I and Mse I, the amount of DNA, the dilution times for ligated products and pre-amplification products) were optimized with 20μL reaction system. The reaction system was established as follows:7 hours (37℃3.5h; 65℃3.5h) of DNA digestion; 1U of EcoR I and Mse I enzymes, respectively; 3μL (50ng/μL) of DNA; 5μL of ligated products diluted by 10 times; and 4μL of pre-amplification products diluted by 70 times.2) 8 primer combinations were taken to generate 402 clearly identifiable bands of 144 individuals from 6 populations, and 289 bands were polymorphic (PPB=71.89%). Population HS (PPB=55.97%,h=0.2065, I=0.3047) had the highest genetic variation, whereas population GD (PPB=44.53%, h=0.1519,I=0.2284) had the lowest genetic variation.3) The six populations of Larix principis-rupprechtii Mayr. had a high level of gene diversity (Ht=0.2245,Hs=0.1810, Gst=0.1936), distributed mainly within (80.64%) rather than among (19.36%) populations. The gene flow among populations was at a high probability (Nm=2.0821).4) The Nei's unbiased measures (1978) of genetic identity (I) was ranged from 0.9269 to 0.9677, and the average was 0.9409. The genetic distance (D) was in the range of 0.0328-0.0759, and the average was 0.0610. While closely related, the six populations were not completely consistent. The highest genetic identity (I=0.9677) and lowest genetic distance (D=0.0328) was detected between populations GD and LY, while the lowest genetic identity (I=0.9269) and highest genetic distance (D=0.0759) was detected between population LL and HS. The result of UPGMA cluster analysis showed that six populations could be divided into three groups:WT and LL; LY and GD; HS and TY.