Cytochrome P450 diversification and hostplant utilization patterns in specialist and generalist moths: birth, death, and adaptation

Across insect genomes, the size of the cytochrome P450 monooxygenase (CYP) gene superfamily varies widely. CYPome size variation has been attributed to reciprocal adaptive radiations in insect detoxification genes in response to plant biosynthetic gene radiations driven by coevolution between herbivores and their chemically defended hostplants. Alternatively, variation in CYPome size may be due to random “birth and death” processes, whereby exponential increase via gene duplications is limited by random decay via gene death or transition via divergence. We examined CYPome diversification in the genomes of seven Lepidoptera species varying in host breadth from monophagous (Bombyx mori) to highly polyphagous (Amyelois transitella). CYPome size largely reflects the size of Clan 3, the clan associated with xenobiotic detoxification, and to some extent phylogenetic age. Consistently across genomes, families CYP6, CYP9, and CYP321 are most diverse and CYP6AB, CYP6AE, CYP6B, CYP9A, and CYP9G a...在昆虫基因组中，细胞色素P450单加氧酶（cytochrome P450 monooxygenase, CYP）基因超家族的大小差异悬殊。CYP组（CYPome）大小的变异此前被归因于：植食性昆虫与其具有化学防御机制的寄主植物协同演化所驱动的植物生物合成基因辐射，进而引发昆虫解毒基因的协同适应性辐射。另有假说认为，CYP组大小的变异可能源于随机的“出生-死亡”进化过程：即通过基因复制实现的指数级增长，会被基因丢失或序列趋异分化所带来的随机衰变所限制。本研究对7种鳞翅目（Lepidoptera）昆虫的基因组开展了CYP组多样化分析，这些物种的寄主范围跨度从单食性的家蚕（Bombyx mori）到高度多食性的杏螟（Amyelois transitella）。CYP组大小主要与3族（Clan 3）的规模相关——该族与异生物质解毒功能密切相关，同时在一定程度上也与系统发育年龄有关。在所有受试基因组中，CYP6、CYP9和CYP321家族的多样性最高，而CYP6AB、CYP6AE、CYP6B、CYP9A及CYP9G……