Analysis of cytochrome P450 contribution to evolved plant toxin resistance in Drosophila sechellia

Drosophila sechellia is a dietary specialist species of fruit fly that has evolved resistance to the toxic secondary defence compounds produced by the fruit of its preferred host plant Morinda citrifolia. The genetic basis of adult toxin resistance is the result of evolution at five loci across the genome. Genetic mapping between D. sechellia and Drosophila simulans and subsequent functional studies in Drosophila melanogaster have identified candidate genes potentially underlying one locus involved in toxin resistance but the remainder of the genes involved are unknown. Genes in the mixed function oxidase or cytochrome P450 gene family are frequently utilized in evolved toxin resistance in insects, yet whether they play a role in D. sechellia's resistance to the toxins found in its host plant is unknown. Here we test the role of cytochrome P450 enzymatic activity in evolved resistance to the two primary toxins found in M. citrifolia fruit: octanoic acid and hexanoic acid. We found that ...西氏果蝇（Drosophila sechellia）是一类食性特化的果蝇，已演化出对其偏好寄主植物海巴戟（Morinda citrifolia）果实所产生的有毒次生防御化合物的抗性。成虫毒素抗性的遗传基础是基因组内五个位点发生演化的结果。通过西氏果蝇与模拟果蝇（Drosophila simulans）之间的遗传作图，以及后续在黑腹果蝇（Drosophila melanogaster）中的功能研究，现已鉴定出与毒素抗性相关的其中一个位点的潜在候选基因，但其余相关基因仍未明确。混合功能氧化酶（mixed function oxidase）或细胞色素P450（cytochrome P450）基因家族的基因，在昆虫演化获得的毒素抗性中常被利用，但这类基因是否参与西氏果蝇对其寄主植物毒素的抗性仍属未知。本研究针对细胞色素P450酶活性在西氏果蝇对抗海巴戟果实中两种主要毒素——辛酸（octanoic acid）和己酸（hexanoic acid）——的演化抗性中的作用展开验证。我们发现……