College of Crop Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China; State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fuzhou, China.
College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
Pestic Biochem Physiol. 2019 Feb;154:60-66. doi: 10.1016/j.pestbp.2018.12.006. Epub 2018 Dec 18.
Generalist phytophagous insects adapt to adventurous chemical environment in a wide variety of host plants by extraordinary detoxifying metabolic abilities. However, how polyphagous insect cope with the diversity of plant defenses remains largely unknown and only a few counter-defense genes detoxifying a wide range of toxic secondary metabolites have been well characterized. Here, we identify a cytochrome P450 gene (CYP6AB60) from tobacco cutworm (Spodoptera litura) in response to three different plant's defense metabolites. After being exposed to artificial diet supplemented with coumarin (COU), xanthotoxin (XAN) or tomatine (TOM), activities of P450 and CYP6AB60 transcript levels in both midgut and fat body tissues were significantly increased. Developmental expression analysis revealed that CYP6AB60 was expressed highly during the larval stages, and tissue distribution analysis showed that CYP6AB60 was expressed extremely high in the midgut, which correspond to the physiological role of CYP6AB60 from S. litura larvae in response to plant allelochemicals. Furthermore, when larvae are injected with double-stranded RNA (dsRNA) specific to CYP6AB60, levels of this transcript in the midgut and fatbody decrease and the negative effect of plant's defense metabolites on larval growth is magnified. These data demonstrate that the generalist insect S. litura might take advantage of an individual detoxificative gene CYP6AB60 to toxic secondary metabolites from different host plants. The CYP6AB60 can be a potential gene to carry out RNAi-mediated crop protection against the major polyphagous pest S. litura in the future.
多食性植食性昆虫通过非凡的解毒代谢能力，适应了广泛宿主植物中冒险的化学环境。然而，多化性昆虫如何应对植物防御的多样性在很大程度上仍然未知，只有少数几种解毒多种有毒次生代谢物的解毒基因得到了很好的描述。在这里，我们从烟草夜蛾（Spodoptera litura）中鉴定出一个细胞色素 P450 基因（CYP6AB60），该基因对三种不同植物防御代谢物有反应。在用香豆素（COU）、黄樟素（XAN）或番茄素（TOM）补充的人工饲料中暴露后，中肠和脂肪体组织中的 P450 和 CYP6AB60 转录本水平的活性显著增加。发育表达分析显示，CYP6AB60 在幼虫阶段表达量较高，组织分布分析显示，CYP6AB60 在中肠中表达量极高，这与 CYP6AB60 在 S. litura 幼虫对植物化感物质的生理作用相对应。此外，当幼虫被针对 CYP6AB60 的双链 RNA（dsRNA）注射时，中肠和脂肪体中的这种转录本水平下降，植物防御代谢物对幼虫生长的负面影响放大。这些数据表明，一般昆虫 S. litura 可能利用单个解毒基因 CYP6AB60 来解毒来自不同宿主植物的有毒次生代谢物。CYP6AB60 可以成为未来针对主要多化性害虫 S. litura 的 RNAi 介导作物保护的潜在基因。
