Population Genetic Diversity And Structure Of Elsino? Arachidis In Liaoning,Hebei And Shandong Provinces

Peanut scab caused by Elsino?arachidis was one of the most important disease in Chinese peanut production.This disease caused wrinkle on peanut leaves and stems,leading to weak growth and yield reduction.Production loss in general diseased yield was 10%-30%and over 50%when it was severe,restricting development of peanut industry.After reported in Guangdong of epidemic,the disease was found gradually in Guangxi,Fujian,Henan,Jiangsu and Hebei Provinces.The disease bursted into sudden epidemic in Liaoning Province in 2011,just one year after firstly found in several locations in Xingcheng,which caused huge amount of reduction and economic loss.As a newly emerged disease in Liaoning,origin of the pathogen was still unknown,limiting resistant variety management and distribution.In this paper,the pathogen genetic structure in Liaoing,Hebei and Shandong Provinces was estimated to make it clear that how was the genetic diversity and divergence distributed and pathogenic relationship among the 3 provinces.1.Samling,identification and cultural morpholocical characteristics of E.arachidisMore than 3,000 diseased specimens from Liaoning,Hebei,Shandong,Jiangsu,Fujian and Guangxi were collected and 519 isolates was successfully isolated in optimal tissue isolation,375 of which were to test in this study.Morpholocical and molecular characteristics were used and the isolates were all identified as E.arachdis.Cultural characteristics of E.arachdis on PDA diversed significantly.The 30-day colony on PDA raised and wrinkled irregularly.Some isolates were covered with dense aerial mycelium while others were scanty or even none aerial mycelium displayed.Most of the isolates were with a circle of red pigment by the colony margin.Colony diameter were 0.67-3.76 cm.2.Establishment and Optimization of ISSR-PCR Reaction System for E.arachidisIn order to build a foundation for genetic diversity research,ISSR-PCR reaction system of E.arachidis was established and optimized.The optimal system of E.arachidis was as follows:2.0 mmol/L Mg²⁺,0.2 mmol/L dNTPs,1.5 U Taq DNA polymerase,0.88?mol/L primer,30-40 ng DNA template.Eight primers were screened for genetic diversity research.3.Genetic diversity of E.arachidis in Liaoing,Hebei and Shandong ProvincesIn Liaoning Province,Nei's genetic diversity index?H?and Shannon index?I?were 0.26and 0.37 of the whole population as well as these among subpopulations ranged from 0.14 to0.25 and 0.20 to 0.37.Divergence index was 0.087⁰.25.Xingcheng,Shenyang and Jinzhou populations were close in genetic distance.Genetic divergence between each province's subpopulations were insignificant.4.Comparision of genetic structure of E.arachidis in Liaoning,Hebei and Shandong Provinces and pathogen relationship analysis.By comparing genetic structure among three populationgs,pathogen relationship were analysed firstly.Ranking of genetic diversity was Liaoning,Hebei and Shandong and gene flow was frequent between populations with a range of 5.032-10.010 showed insignificant genetic divergence.AMOVA showed that 82%variance was within subpopulations,10%was among subpopulations and only 8%were among the three populations.PCA showed greater variance in Liaoning Province and larger overlapping area between Liaoing and Shandong populations.Four genetic groups were divided with a different distribution in each population.Three groups were shared by the three populations and only one was in Liaoing Province.Genetic distance was closer between Liaoning and Shandong populations than Liaoing and Hebei populations.Combined with field investigation,pathogen relationship was analysed preliminarily:partial Liaoing population was from Shandong and Hebei populations and partial Hebei population was from Hebei.