Key Laboratory of Forest Disaster Warning and Control of Yunnan Province, Southwest Forestry University, Kunming 650224, China.
Key Laboratory of Forest Disaster Warning and Control of Yunnan Province, Southwest Forestry University, Kunming 650224, China.
Comp Biochem Physiol B Biochem Mol Biol. 2020 Jun;243-244:110431. doi: 10.1016/j.cbpb.2020.110431. Epub 2020 Mar 4.
The longhorned beetles, Rhaphuma horsfieldi and Xylotrechus quadripes, are two polyphagous insects with larvae feeding on different host plants. In this study, we identified and characterized three gene superfamilies of cytochrome P450s (CYPs), carboxylesterases (COEs) and glutathione-S-transferases (GSTs) involved in the detoxification of endobiotics (e.g., hormones and steroids) and xenobiotics (e.g., insecticides, sex pheromones and plant allelochemicals) through a combination approach of bioinformatics, phylogenetics, expression profiles and genomics. Transcriptome analyses led to the identification of 281 transcripts encoding 135 P450s, 108 COEs and 38 GSTs from the two beetles, coupled with comparative studies of detoxification genes among coleopteran species, suggesting a correlation between host range and the sizes of P450 or COE gene repertoires. The P450s of two beetles were phylogenetically classified into four clades, representing the majority of genes in the CYP3 clan. The COEs from R. horsfieldi and X. quadripes were separately grouped into 11 and 10 clades, and the GST superfamily was assigned into six clades. Expression profiles revealed that the detoxification genes were broadly expressed in various tissues as an implication of functional diversities. Ultimately and more importantly, five alternative splicing events in the Epsilon GSTs, including RhorGSTe7.1/GSTe7.2 and XquaGSTe3.1/GST3.2, were acquired in Coleoptera, in which these genes and their orthologs shared highly conserved gene structure. Our current study has complemented the resources for the detoxification genes in the family Cerambycidae, and allows for functional experiments to identify candidate molecular targets involved in pest resistance to insecticides like organophosphates, organochlorines and pyrethroids.
长角象甲科昆虫，包括印度谷螟和四纹豆象，是两种多食性昆虫，幼虫以不同的寄主植物为食。在本研究中，我们通过生物信息学、系统发生学、表达谱和基因组学相结合的方法，鉴定和描述了三个基因超家族，即细胞色素 P450s（CYPs）、羧酸酯酶（COEs）和谷胱甘肽-S-转移酶（GSTs），它们参与内源性物质（如激素和类固醇）和外源性物质（如杀虫剂、性信息素和植物化感物质）的解毒。转录组分析导致从两种甲虫中鉴定出 281 个编码 135 个 P450s、108 个 COEs 和 38 个 GSTs 的转录本，加上对鞘翅目物种解毒基因的比较研究，表明寄主范围与 P450 或 COE 基因库的大小之间存在相关性。两种甲虫的 P450s 被系统发生学分为四个分支，代表了 CYP3 家族中的大部分基因。R. horsfieldi 和 X. quadripes 的 COEs 分别分为 11 个和 10 个分支，GST 超家族分为 6 个分支。表达谱显示，解毒基因在各种组织中广泛表达，暗示其功能多样性。最终，更重要的是，Epsilon GSTs 中的五个选择性剪接事件，包括 RhorGSTe7.1/GSTe7.2 和 XquaGSTe3.1/GST3.2，在鞘翅目动物中获得，其中这些基因及其同源基因具有高度保守的基因结构。我们目前的研究补充了象甲科昆虫解毒基因的资源，并允许进行功能实验，以鉴定参与害虫对有机磷、有机氯和拟除虫菊酯等杀虫剂产生抗性的候选分子靶标。
