The enrichment of transposable elements (TEs) within allelochemical- and insecticide-metabolizing P450 alleles in Helicoverpa zea enables these P450s to gain TE-introduced adaptive variations otherwise not readily available to cope with the ever-changing and diverse xenobiotic stress factors in varying cropping systems. The critical role of each TE-inserted P450 allele depends on whether the inserted P450 allele is more adaptive than its TE-free counterpart or not. Previous study has reported a HzSINE1-inserted CYP321A2 allele in a laboratory strain of H. zea reared with xenobiotic-free artificial diets. Here we show that the HzSINE1-inserted CYP321A2 allele transcribes into two HzSINE1 sequence-containing mutant mRNA isoforms of different length that encode an identical C terminus-truncated and heme-binding region deleted non-functional P450. Nonetheless, HzSINE1 insertion does not disrupt the regulatory functional aspect of CYP321A2 since this allele is constitutively expressed and highly inducible by the allelochemicals xanthotoxin, quercetin and chlorogenic acid. Furthermore, while the HzSINE1-inserted CYP321A2 allele is fixed in the laboratory strain, the insertion is purged in the bifenthrin-resistant strain and the Georgia field population of H. zea. To sum up, the HzSINE1-inserted CYP321A2 allele represents an allelochemical-inducible non-functional P450 allele that is selected against in the field populations frequently encountering toxic plant allelochemicals and synthetic insecticides. However, such an insertion can reach fixation under the xenobiotic-free laboratory rearing conditions most likely due to random genetic drift across multiple generations.

Helicoverpa zea 中化感化学和杀虫剂代谢 P450 等位基因中转座因子 (TE) 的富集使这些 P450 能够获得 TE 引入的适应性变异，否则不容易应对不同种植系统中不断变化和多样化的外源胁迫因素. 每个插入 TE 的 P450 等位基因的关键作用取决于插入的 P450 等位基因是否比其不含 TE 的对应物更具适应性。先前的研究报告了在用不含外源生物的人工饲料饲养的H. zea实验室菌株中插入了HzSINE1 的CYP321A2等位基因。在这里我们展示了插入HzSINE1 的CYP321A2等位基因转录成两个编码相同 C 末端截短和血红素结合区的不同长度的包含HzSINE1序列的突变 mRNA 同种型缺失的非功能性 P450。尽管如此，HzSINE1插入不破坏的调节功能方面CYP321A2因为该等位基因是组成型表达和由感物质花椒毒素，槲皮素和绿原酸高度可诱导的。此外，虽然HzSINE1 -inserted CYP321A2等位基因被固定在实验室菌株中，插入吹扫在抗性联苯菊酯菌株和乔治亚字段人口谷实夜蛾。综上所述，插入HzSINE1的CYP321A2等位基因代表一种化感化学诱导的非功能性 P450 等位基因，在经常遇到有毒植物化感化学物质和合成杀虫剂的田间种群中选择该等位基因。然而，这种插入可以在无外源性实验室饲养条件下达到固定，最有可能是由于跨多代的随机遗传漂移。