茶尺蠖(Ectropis oblIQua Prout)是我國茶樹主要害蟲之一，遍及我國各主產茶區，尤以浙、蘇、皖地區發生嚴重。課題組在前期研究中發現，不同地區茶尺蠖種群對茶尺蠖核型多角體病毒敏感性差異明顯，最大差異達到700余倍。
為了深入了解和揭示不同茶區茶尺蠖種群的遺傳分化，課題組通過收集全國8省17個地區茶尺蠖種群，以不同地理種群茶尺蠖為研究材料，測定了這些種群的線粒體序列，比較其同源性及序列多態性，構建單倍型分子系統發育樹，將茶尺蠖17個種群分為兩大類群，將兩個不同類群間的茶尺蠖種群進行遺傳雜交。研究發現，其產生的雜交F1代生長發育不正常，性比嚴重失衡，且F1代自交后不能產生可育的F2代;而來自同一類群的茶尺蠖種群間雜交，其后代均能正常生長發育。
這說明，兩個類群間的茶尺蠖存在著生殖隔離，遺傳分化已達到種間水平，這為進一步明確茶尺蠖是否存在近緣種或隱種以及這些種的分布提供了研究基礎，同時為科學有效使用病毒防治茶尺蠖提供了依據。
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. |
