Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, College of Crop Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, College of Crop Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
Pestic Biochem Physiol. 2019 Jun;157:211-218. doi: 10.1016/j.pestbp.2019.03.020. Epub 2019 Apr 1.
Herbivore attack leads to enhanced production of defensive compounds to mount anti-herbivore defense in plants via activation of the jasmonate signaling pathway. On the other hand, some herbivores can eavesdrop on plants defense signaling and up-regulate their cytochrome P450 genes to increase detoxification of defensive compounds. However, the ecological risk of eavesdropping on plant defense signaling is largely unknown. In this study, we examined the induction of cytochrome P450s by methyl jasmonate (MeJA) and its consequence on the toxicity of aflatoxin B1 (AFB1) to Helicoverpa armigra larvae. The results show that MeJA applications either in a diet or volatile exposure enhanced the toxicity of AFB1 to the larvae. RNA sequences analysis revealed that cytochrome P450 CYP6AE19 was highly induced when MeJA was applied with AFB1. In addition, HaGST encoding glutathione-S-transferase that mainly transforms aflatoxin B1 exo-8,9-epoxide to aflatoxin B1 exo-8,9-glutathione was also induced. RNA interference of CYP6AE19 via injecting a double-stranded RNA decreased mortality of larvae exposed to AFB1; while injecting a double-stranded RNA of HaGST increased larval mortality. Furthermore, a protein model was generated and a subsequent docking simulation for AFB1 suggests the bioactivation as a major mechanism of AFB1. This study provides evidence that MeJA increased larval mortality of H. armigera via induction of CYP6AE19 that can bioactivate AFB1.
食草动物的攻击会导致植物通过茉莉酸信号通路激活来增强防御化合物的产生，从而产生抗食草动物防御。另一方面，一些食草动物可以监听植物的防御信号，并上调细胞色素 P450 基因以增加防御化合物的解毒能力。然而，监听植物防御信号的生态风险在很大程度上是未知的。在这项研究中，我们研究了茉莉酸甲酯（MeJA）对细胞色素 P450 的诱导及其对美洲棉铃象幼虫中黄曲霉毒素 B1（AFB1）毒性的影响。结果表明，无论是在饮食中还是在挥发物暴露中，MeJA 的应用都增强了 AFB1 对幼虫的毒性。RNA 序列分析显示，当 MeJA 与 AFB1 一起应用时，细胞色素 P450 CYP6AE19 被高度诱导。此外，编码主要将黄曲霉毒素 B1 外-8,9-环氧化物转化为黄曲霉毒素 B1 外-8,9-谷胱甘肽的 HaGST 也被诱导。通过注射双链 RNA 干扰 CYP6AE19 降低了暴露于 AFB1 的幼虫的死亡率；而注射 HaGST 的双链 RNA 则增加了幼虫的死亡率。此外，还生成了一个蛋白质模型，并对 AFB1 进行了随后的对接模拟，表明生物激活是 AFB1 的主要机制。这项研究提供了证据表明，MeJA 通过诱导可以生物激活 AFB1 的 CYP6AE19 增加了美洲棉铃象幼虫的死亡率。
