茶尺蠖(Ectropis oblIQua Prout)是我国茶树主要害虫之一，遍及我国各主产茶区，尤以浙、苏、皖地区发生严重。课题组在前期研究中发现，不同地区茶尺蠖种群对茶尺蠖核型多角体病毒敏感性差异明显，最大差异达到700余倍。
为了深入了解和揭示不同茶区茶尺蠖种群的遗传分化，课题组通过收集全国8省17个地区茶尺蠖种群，以不同地理种群茶尺蠖为研究材料，测定了这些种群的线粒体序列，比较其同源性及序列多态性，构建单倍型分子系统发育树，将茶尺蠖17个种群分为两大类群，将两个不同类群间的茶尺蠖种群进行遗传杂交。研究发现，其产生的杂交F1代生长发育不正常，性比严重失衡，且F1代自交后不能产生可育的F2代;而来自同一类群的茶尺蠖种群间杂交，其后代均能正常生长发育。
这说明，两个类群间的茶尺蠖存在着生殖隔离，遗传分化已达到种间水平，这为进一步明确茶尺蠖是否存在近缘种或隐种以及这些种的分布提供了研究基础，同时为科学有效使用病毒防治茶尺蠖提供了依据。
原文摘要：
Detecting Deep Divergence in Seventeen Populations of Tea Geometrid (Ectropis obliqua Prout) in China by COI mtDNA and Cross-Breeding
Gui-Hua Zhang, Zhi-Jun Yuan, Chuan-Xi Zhang, Kun-Shan Yin, Mei-Jun Tang, Hua-Wei Guo, Jian-Yu Fu mail, Qiang Xiao
The tea geometrid (Ectropis obliqua Prout, Lepidoptera: Geometridae) is a dominant chewing insect endemic in most tea-growing areas in China. Recently some E. obliqua populations have been found to be resistant to the nucleopolyhedrovirus (EoNPV), a host-specific virus that has so far been found only in E. obliqua. Although the resistant populations are morphologically indistinguishable from susceptible populations, we conducted a nationwide collection and examined the genetic divergence in the COI region of the mtDNA in E. obliqua. Phylogenetic analyses of mtDNA in 17 populations revealed two divergent clades with genetic distance greater than 3.7% between clades and less than 0.7% within clades. Therefore, we suggest that E. obliqua falls into two distinct groups. Further inheritance analyses using reciprocal single-pair mating showed an abnormal F1 generation with an unbalanced sex ratio and the inability to produce fertile eggs (or any eggs) through F1 self-crossing. These data revealed a potential cryptic species complex with deep divergence and reproductive isolation within E. obliqua. Uneven distribution of the groups suggests a possible geographic effect on the divergence. Future investigations will be conducted to examine whether EoNPV selection or other factors prompted the evolution of resistance. |
