Bacillus thuringiensis (Bt) insecticide is currently the most widely used bioinsecticide. Bt expressing cry genes are some of the most successful foreign-genome-inserting genes used in transgenic insect-resistant crop development. Cry toxins are resistant to lepidopteran pests, such as Chilo suppressalis, a major insect pest of rice worldwide. Since Cry toxins exert their activity by binding to specific receptors in the midgut of target insects, identification of functional Cry toxin receptors in the midgut of C. suppressalis larvae is crucial to evaluate potential resistance mechanisms and develop effective strategies for inhibiting insect resistance. In this study, we isolated two aminopeptidase N genes (APN6 and APN8) from C. suppressalis and determined that they were expressed in the foregut. APN6 was highly expressed at the fourth instar, and APN8 was highly expressed in adult and pupa. Knockdown of CsAPN6 and CsAPN8 by RNA interference resulted in significantly decreased susceptibility of larvae to Bt rice varieties TT51 (expressing cry1Ac/cry1Ab fusion genes) and T1C-19 (expressing cry1Ca), but not T2A-1 (expressing cry2Aa). These findings suggest that both APN6 and APN8 are involved in the toxicity of Cry1Ac/Cry1Ab and Cry1Ca toxins.

中文翻译：

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抑制氨肽酶 N 基因会降低抑制 Chilo 幼虫对 Cry1Ab/Cry1Ac 和 Cry1Ca 的易感性

苏云金芽孢杆菌（Bt）杀虫剂是目前应用最广泛的生物杀虫剂。Bt 表达cry 基因是用于转基因抗虫作物开发的一些最成功的外源基因组插入基因。Cry 毒素对鳞翅目害虫具有抗性，例如世界范围内水稻的主要害虫 Chilo suppressalis。由于 Cry 毒素通过与目标昆虫中肠中的特定受体结合来发挥其活性，因此鉴定抑制 C. 幼虫中肠中的功能性 Cry 毒素受体对于评估潜在的抗性机制和制定抑制昆虫抗性的有效策略至关重要。在这项研究中，我们从抑制 C.suppressalis 中分离出两个氨肽酶 N 基因（APN6 和 APN8），并确定它们在前肠中表达。APN6在四龄高表达，APN8在成虫和蛹中高表达。通过RNA干扰敲除CsAPN6和CsAPN8导致幼虫对Bt水稻品种TT51（表达cry1Ac/cry1Ab融合基因）和T1C-19（表达cry1Ca）的易感性显着降低，但不影响T2A-1（表达cry2Aa）。这些发现表明 APN6 和 APN8 都与 Cry1Ac/Cry1Ab 和 Cry1Ca 毒素的毒性有关。