国际蚜虫基因组联盟已成功地对农业害虫“蚜虫”进行了基因组测序。根据对蚜虫基因信息的解读，研究人员期冀将来能开发出防治蚜虫的有效方法。该研究成果发表于2月23日美国《公共科学图书馆·生物学》杂志的网络版上。

蚜虫是以植物的韧皮部流体为食物的小型昆虫，不但以集团形式吸取植物的养分，而且是传播植物病毒的媒介，给全世界农作物带来巨大灾害。蚜虫能够收纳合成营养成分的共生细菌，并从一亿年前逐代相传，因此与各种微生物有着密切的关系。蚜虫还可以适应环境条件的变化，不断在单性繁殖和有性繁殖之间切换，变换自如地产生出各种表现形态。蚜虫由于具有非常奇特的生物学特性，也因而成为基础生物学研究重要的生物模型。

国际蚜虫基因组联盟的研究小组在北美采集到“豌豆蚜虫”，并提取其DNA，利用鸟枪法（shotgun sequence method）对其基因序列进行排序。在全基因组5亿个碱基对中，绘制了其中约4亿5000万个碱基对的序列图谱。国际研究小组利用计算机对遗传基因进行了预测，并对其中部分基因实行了手动结构验证，以对自动预测结果进行修正。

结果发现，蚜虫在昆虫中具有数量最多的遗传基因35000个。研究人员证实蚜虫具有非常独特的基因组特性：大量基因重复，重复基因在昆虫中属最多，约达2500组，总数13000个基因；免疫相关基因大量缺失；代谢相关基因组与蚜虫巴克纳氏菌构成辅助代谢体系；从共生细菌获得10种以上的基因，多发现于菌细胞。

研究人员认为，大量重复基因的发现，如单性生殖基因、信号传输复制基因和对病毒媒介起重要作用的膜输送相关基因，对揭开蚜虫独特特性的分子基础起到了重要作用。蚜虫放弃对来自外部微生物的攻击能力，使其成功地与各种微生物形成共生。蚜虫与共生细菌等各种异种生物就像一个生物一样协调代谢，构筑成二者不可分的关系。

人们一般使用药物对蚜虫进行防治，但化学药物防治害虫损害人类健康及增加环境的负担。近年来，已出现了对农药具有耐药性的蚜虫群。此次蚜虫基因组测序研究，不但使人们对蚜虫的特异生物学特性有了更深入的了解，还将对发生学、进化学、生态学、动物学、微生物学等生物学的广泛领域造成了巨大影响。

原始出处：

PLoS Biol 8(2): e1000313. doi:10.1371/journal.pbio.1000313

Genome Sequence of the Pea Aphid Acyrthosiphon pisum

The International Aphid Genomics Consortium

Aphids are important agricultural pests and also biological models for studies of insect-plant interactions, symbiosis, virus vectoring, and the developmental causes of extreme phenotypic plasticity. Here we present the 464 Mb draft genome assembly of the pea aphid Acyrthosiphon pisum. This first published whole genome sequence of a basal hemimetabolous insect provides an outgroup to the multiple published genomes of holometabolous insects. Pea aphids are host-plant specialists, they can reproduce both sexually and asexually, and they have coevolved with an obligate bacterial symbiont. Here we highlight findings from whole genome analysis that may be related to these unusual biological features. These findings include discovery of extensive gene duplication in more than 2000 gene families as well as loss of evolutionarily conserved genes. Gene family expansions relative to other published genomes include genes involved in chromatin modification, miRNA synthesis, and sugar transport. Gene losses include genes central to the IMD immune pathway, selenoprotein utilization, purine salvage, and the entire urea cycle. The pea aphid genome reveals that only a limited number of genes have been acquired from bacteria; thus the reduced gene count of Buchnera does not reflect gene transfer to the host genome. The inventory of metabolic genes in the pea aphid genome suggests that there is extensive metabolite exchange between the aphid and Buchnera, including sharing of amino acid biosynthesis between the aphid and Buchnera. The pea aphid genome provides a foundation for post-genomic studies of fundamental biological questions and applied agricultural problems.