Genetic Study Of Different Population Of Ectropis Obliqua Using Mitochondrial Gene/Ribosomal Gene Markers And Cross-Breeding

In this study, the inheritance structures of17tea geometrid populations that are distributed in8provinces in China was analyzed using mtDNA COI and rDNA ITS2molecule markers. Thecross-breeding experiments were conducted with different geographical groups of Ectropis obliquaProut and the experiment data suggests reproduction isolation between different geographical groups ofEctropis obliqua Prout exists. The main results are as follows:1.Mitochondrial DNA COI gene sequences of171individuals of tea geometrid from17differentgeographical populations have been cloned and sequenced. The homologous of all sequences arecompared, with nucleotide composition calculated and molecular phylogenetic tree constructed bymethods of Maximum Likelihood （ML） and Maximum Parsimony （MP） respectively. Through thesequential analysis, it is found that A+T accounts for70.6%of657bp fragment where77nucleotidemutations exist.50haplotypes were detected in171sequences. Haplotype diversity index （Hd） andmean nucleotide diversity index （Pi） were0.7315and0.01818respectively. The mean gene flow （Nm）among17populations was0.05, and the stable index of the overall group Fst was0.8773. Molecularphylogenetic tree was constructed by the Maximum Likelihood, Maximum Parsimony and Bayesionmethods, with the sequences from Buzura suppressaria and Scopula subpunctaria Herrich-Schaeffer asoutgroups. The analysis of phylogenetic trees indicates that all haplotypes clustered in2biotypes. Ibiotype included HZ, YH, YX and SZZ populations, while other haplotypes clustered together belongsto II biotype. The genetic distance between two biotypes is0.037⁰.042.2.Ribosomal DNA ITS gene sequences of151individuals tea geometrid from17differentgeographical populations were tested and systematic phylogenetic tree analysis were conducted. Wecompared the homologous sequences and calculated nucleotide compositions of all the individuals.Based on sequential analysis, we found that G+C make up about63.2%in the484bp fragment of teageometrid including52nucleotide mutations.50haplotypes were detected in151individuals, withhaplotype diversity index （Hd）0.789and mean nucleotide diversity index （Pi）0.0055. The analysis ofphylogenetic trees and the genetic distance suggest that there is no obvious evidence of geneticdifferentiation among populations on the ITS level.3.Four populations from two biotypes are selected for cross-breeding experiments based on theresults of molecular phylogenetic analysis. The research suggests that reproductive isolation betweenYH population and SY population exists. The statistics analysis of hybridization test suggests thatemerging rate of the adult of hybrid F₁is few, and no female adults of hybrids （F₁） exist based oncross-breeding （SY×YH）. It also shows the unbalance of sex proportion and hatching rate of hybridscross-breeding （YH×SY）. What’s more, the hybrids （F₁） are sterile. In other words, no reproductionisolation between WY population and QS population exists. The results show that hybrids F₁are thesame as parents on hatching rate, larvae duration, pupa weight, emerging rate and the number ofoviposition of adults. Hatching rate of hybrid F₂is normal.