不同地理种群美洲斑潜蝇及近缘种的rDNA-ITS1序列分析和比较

Sequence analysis and comparison of rDNA-ITS1 of geographical populations of Liriomyza sativae Blanchard (Diptera: Agromyzidae) from China and closely related species

目的通过对美洲斑潜蝇Liriomyzasativae Blanchard不同地理种群及近缘种间的核糖体DNA第一内转录间隔区（rDNA-ITS1）进行比较,分析美洲斑潜蝇不同地理种群间的遗传分化情况,并为美洲斑潜蝇与近缘种间提供分子鉴别标记。方法用PCR产物直接测序法及克隆测序法对我国美洲斑潜蝇8个地理种群的rDNA-ITS1序列进行测序,并调用GenBank中3个近缘种的rDNA-ITS序列,运用软件MEGA3.1对美洲斑潜蝇不同地理种群及近缘种间的rDNA-ITS1序列进行分析。结果美洲斑潜蝇8个地理种群间的分化程度较低,只有8个变异位点,遗传距离都在0.02以下,但4个近缘种间的碱基差异显著,遗传距离为0.149-0.390,有126个变异位点,12个美洲斑潜蝇特异性识别位点。结论虽然基于rDNA-ITS1序列所显示的美洲斑潜蝇各地理种群之间的遗传分化很小,但是其分化趋势与地理分布基本相吻合;得到的12个特异性识别位点不仅可以作为美洲斑潜蝇与其近缘种间鉴别的分子标记,而且可为今后设计鉴别性PCR引物提供重要的参考依据。

[ Aim] To analyze the genetic differentiation of rDNA-ITS1 sequences among the geographical populations of Liriomyza sativae Blanchard and to provide molecular markers for identifying L. sativae against its closely related species. [ Method] rDNA-ITSI regions of eight geographical populations of L. sativae from China were sequenced by using PCR product sequencing method or clone sequencing method, and rDNA-ITSI sequences of three closely related species （L. trifolii, L. huidobrensis, and L. bryoniae ） were retrieved from GenBank. The rDNA-ITSI sequences among populations of L. sativae and their closely related species were analyzed using MEGA3.1. [ Results ] The ITSI difference among the geographical populations of L. sativae was very low, with only 8 variable sites for L. sativae and genetic distance below 0.02. But the difference of the ITSI sequences among L. sativae and its closely related species was significant, with 126 variable sites, 12 authenticable sites for L.sativae and genetic distance between 0.149 - 0.390. [Conclusion] Despite of the low diversity, the trends of differentiation of geographical populations of L. sativae were consistent with the geographical distribution. The characteristics of rDNA ITS sequence can be used as good markers for authenticating L. sativae populations form their closely related species.