基于COI基因全长序列的假眼小绿叶蝉地理种群遗传分化研究

假眼小绿叶蝉Empoasca vitis(Gthe)是我国大陆茶区分布最广、为害最重的茶树害虫,其种群世代重叠严重,数量大。从我国13个主要产茶省份各选出一个重点产茶县(市),采集假眼小绿叶蝉标本,首次扩增得到其线粒体CO I基因全长序列,并以此探讨了假眼小绿叶蝉13个地理种群间的遗传多样性、分子变异、遗传分化程度及基因流水平。在13个地理种群中共得到了176条CO I基因序列,发现了113个变异位点,形成了105个CO I单倍型。总群体单倍型多样性Hd为0.9720,种群内单倍型多样性在0.804—1.000范围内,总群体和各种群的Tajima's D检验结果均不显著,说明茶园假眼小绿叶蝉的进化符合中性模型,种群数量较为稳定。AMOVA分子变异分析结果表明,茶园假眼小绿叶蝉的遗传分化主要来自于种群内部。Mantel检验显示各地理种群的遗传距离与地理距离之间不具有显著的相关性。总群体的遗传分化系数Gst为0.03652,固定系数Fst为0.10876,基因流Nm为4.097,表明地理种群间存在较频繁的基因交流,遗传差异较小。推测,20世纪90年代以来的省际之间频繁的茶树鲜叶贩运、异地茶苗的大批量调拨等因素促进了假眼小绿叶蝉的长距离迁移,加强了不同种群间的基因交流。

Genetic variation of Empoasca vitis (Göthe) (Hemiptera: Cicadellidae) among different geographical populations based on mtDNA CO I complete sequence

The tea green leafhopper, Empoasca vitis(Göthe), is one of the most important tea-plant pests that causes significant losses on tea leaf production throughout all growing regions in mainland of China. The multiple occurrences of the overlapping generations of this pest have led to serious infestation on tea leaves. Adults were collected from the thirteen primary tea-producing provinces respectively, with each representing one geographic population in the southeastern China. The complete sequences of the entire mtDNACO I gene (x bp) of E. vitis were compared among 13 populations. The genetic structure of these populations was further investigated based on the CO I DNA sequences. A total of 176 CO I gene complete sequences with 113 variable sites and 105 haplotypes were obtained. The haplotype diversity index (Hd) was 0.9720 among all populations, ranging from 0.804 to 1.000 within single population. The Tajima''s D tests for all populations or each single population did not reach any significant level, which suggest that the evolution and the abundance of E. vitison tea plantations remained on quantitative level,which fits well with the neutral model. The Results of ANOVA analyses demonstrated that genetic differentiation of E. vitis mainly occurred within populations. The Mantel test disclosed that the genetic distance among populations was not correlated with the geographic distance. Among the 13 populations, the total genetic differentiation coefficient (Gst) was 0.03652, the total fixation index (Fst) was 0.10876, and the gene flow (Nm) was 4.097. This indicates that the high level of gene exchange does exist in the different geographical populations, but not in genetic variation. We believe that the massive and frequent transportation and plantation of fresh tea leaves and seedlings in different host plant locations among 13 provinces since the 1990s promote the long-distance migration of E. vitis and reinforce the gene flow among these geographically different populations.