基于COI基因5′端与3′端序列田间常见粉虱的分子鉴定

【目的】粉虱种类繁多，个体微小，其种类识别与鉴定常需借助分子生物学技术。本研究旨在明确线粒体COI基因(mitochondrial cytochrome c oxidase subunit I gene) 5′端和3′端序列对常见种类粉虱识别鉴定的可行性。【方法】以我国田间常见的16种粉虱为对象，以COI基因5′端(641 bp)和3′端(738 bp)序列为靶标进行比对分析，以MEGA 5.10软件的K2-P模型计算种内与种间遗传距离，以邻接法(NJ法)构建进化树并进行系统发育分析。【结果】当以5′端为靶标时，16种粉虱的种内平均遗传距离为0.0015，种间平均遗传距离为0.2897，种间遗传距离为种内遗传距离的193.1倍；而且种内、种间遗传距离没有重叠区域。当以3′端为靶标时种内平均遗传距离为0.0007，种间平均遗传距离为0.2817，种间遗传距离为种内遗传距离的402.4倍；但桑粉虱Pealius mori与烟粉虱Bemisia tabaci Asia II 1的种内和种间遗传距离重叠。系统发育分析结果显示，以5′端为靶标时，16种粉虱可以形成独立的进化分支；以3′端为靶标时，除桑粉虱与传统分类学不一致外，其余种类均可形成独立的分支。【结论】结果表明，5′端序列更适用于基于DNA条形码技术的物种识别鉴定研究。

Identification of common whitefly species (Hemiptera: Aleyrodidae) in China based on the 5′- and 3′-end sequences of the COI gene

【Aim】 Whiteflies belong to a species-rich family with small body size. Identification of whitefly species is commonly done with the aid of molecular methods.  This study aims to clarify the effectiveness of the 5′- and 3′-ends of the mitochondrial cytochrome c oxidase subunit I (COI) gene sequences in molecular identification of common whiteflies species. 【Methods】 The COI gene sequences in 16 whitefly species common in China were amplified using the 5′- and 3′-end universal primers. The obtained 5′-end (641 bp) and 3′-end (738 bp) fragments were sequenced. The intra- and inter-species genetic distances were calculated using the Kimura-2-Parameter model; the phylogenetic trees were established by a neighbor-joining (NJ) method of the MEGA (Version 5.10) software.【Results】 The identification based on the phylogenetic tree was consistent with those based on morphological characteristics for the 16 whitefly species when the 5′-end fragments were analyzed. However, when the 3′-end fragments were analyzed, the identification results based on the phylogenetic tree were not consistent with those based on morphological characteristics in the case of Pealius mori and Bemisia tabaci Asia II 1. The average inter-species genetic distance was 193.1 (0.2897 vs. 0.0015) and 402.4 (0.2817 vs. 0.0007) times higher than the corresponding intra-species genetic distance for the 5′- and 3′-end fragments, respectively. There was no overlap between inter- and intra-species genetic distances when the 5′-end fragments were analyzed, but overlap was observed between P. mori and B. tabaci Asia II 1 when the 3′-end fragments were analyzed. 【Conclusion】 The DNA barcoding based on the 5′-end fragment of the partial COI gene can provide a rapid and accurate identification of these whitefly species.