One possible way to overcome the diversity of toxic plant allelochemicals idiosyncratically distributed among potential host plants is to have more counterdefense genes via gene duplication or fewer gene losses. Cytochrome P450 is the most important gene family responsible for detoxification of the diversity of plant allelochemicals. We have recently reported the identification and cloning of the transposon (HzSINE1)-disrupted non-functional CYP321A2, a duplicated paralog of the xenobiotic-metabolizing P450 CYP321A1 from a laboratory colony of Helicoverpa zea. Here we report the identification of the wild-type intact allele of CYP321A2 from another H. zea colony. This CYP321A2 allele encodes a deduced protein of 498 amino acids and has the P450 signature motifs. Quantitative RT-PCR experiments showed that this CYP321A2 allele was highly expressed in midgut and fat body and achieved the highest expression level in the developmental stage of 5th and 3rd instar larvae. CYP321A2 and CYP321A1 were constitutively expressed in low levels but can be differentially and significantly induced by a range of the plant allelochemicals and plant signal molecules, among which xanthotoxin, flavone, and coumarin were the most prominent inducers of CYP321A2 both in midgut and fat body, whereas flavone, coumarin, and indole-3-carbinol were the prominent inducers of CYP321A1 in midgut and fat body. Moreover, xanthotoxin- and flavone-responsive regulatory elements of CYP321A1 were also detected in the promoter region of CYP321A2. Our results enrich the P450 inventory by identifying an allelochemical broadly induced CYP321A2, a paralog of CYP321A1 in H. zea. Our data also suggest that the CYP321A2/CYP321A1 paralogs are a pair of duplicated genes of multigene families and CYP321A2 could potentially be involved in the detoxification of plant allelochemicals and adaptation of H. zea to its chemical environment.

中文翻译：

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玉米夜蛾野生型 CYP321A2 的鉴定以及化感化学诱导的 CYP321A2 及其旁系同源物 CYP321A1 表达谱的比较


克服潜在宿主植物中特殊分布的有毒植物化感物质多样性的一种可能方法是通过基因复制或更少的基因丢失获得更多的反防御基因。细胞色素P450是负责植物化感物质多样性解毒的最重要的基因家族。我们最近报道了转座子 ( HzSINE1 ) 破坏的非功能性CYP321A2的鉴定和克隆，该 CYP321A2 是来自玉米夜蛾实验室菌落的外源代谢 P450 CYP321A1的复制旁系同源物。在这里，我们报告了来自另一个玉米群体的CYP321A2野生型完整等位基因的鉴定。该CYP321A2等位基因编码 498 个氨基酸的推导蛋白，并具有 P450 特征基序。定量RT-PCR实验表明，该CYP321A2等位基因在中肠和脂肪体中高表达，并在5龄和3龄幼虫发育阶段达到最高表达水平。 CYP321A2和CYP321A1以低水平组成型表达，但可以被一系列植物化感化学物和植物信号分子差异显着诱导，其中黄蜂毒素、黄酮和香豆素是中肠和脂肪体中最显着的CYP321A2诱导剂，而黄酮、香豆素和吲哚-3-甲醇是中肠和脂肪体中CYP321A1的主要诱导剂。此外，在CYP321A2的启动子区域也检测到CYP321A1的花黄毒素和黄酮响应调节元件。 我们的结果通过鉴定一种广泛诱导的化感化学CYP321A2 （玉米穗中CYP321A1的旁系同源物）丰富了 P450 库存。我们的数据还表明， CYP321A2 / CYP321A1旁系同源物是多基因家族的一对重复基因， CYP321A2可能参与植物化感物质的解毒和玉米对其化学环境的适应。