College of Agriculture, Anhui Science and Technology University, Fengyang, Anhui 233100, China; Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests/ State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests/ State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
J Insect Physiol. 2022 May-Jun;139:104387. doi: 10.1016/j.jinsphys.2022.104387. Epub 2022 Mar 31.
Insect development is regulated by a combination of juvenile hormone (JH) and 20-hydroxyecdysone (20E). Production of both JH and 20E is regulated by transforming growth factor-β (TGFβ) signaling. TGFβ can be classified into two branches, the Activin and Bone Morphogenetic Protein (BMP) pathways. In Drosophila melanogaster, BMP signaling is critical for JH synthesis, whereas Activin signal is required to generate the large pulse of 20E necessary for entering metamorphosis. However, to which extent the roles of these signals are conserved remains unknown. Here we studied the role of an Activin component Smad on X (Smox) in post-embryonic development in a defoliating ladybird Henosepilachna vigintioctopunctata. RNA interference (RNAi)-aided knockdown of Hvsmox inhibited larval growth, and impaired larval development. All Hvmyo RNAi larvae arrested at the fourth-instar larval stage. Moreover, knockdown of Hvsmox delayed gut and Malpighian tubules remodeling. Furthermore, the expression of a JH biosynthesis gene (Hvjhamt), a JH receptor gene HvMet and a JH response gene HvKr-h1 was greatly enhanced. Conversely, the expression levels of an ecdysteroidogenesis gene (Hvspo), a 20E receptor gene (HvEcR) and six 20E response genes (HvBrC, HvE74, HvE75, HvE93, HvHR3 and HvHR4) were significantly lowered. Knockdown of HvMet partially restored the negative phenotypes in the Hvsmox RNAi beetles. Our results suggest that Smox exerts regulative roles in JH production, ecdysteroidogenesis and organ remodeling, thus contributing to modulate the larva-pupa-adult transformation in H. vigintioctopunctata.
昆虫的发育受保幼激素 (JH) 和 20-羟基蜕皮酮 (20E) 的共同调控。JH 和 20E 的产生受转化生长因子-β (TGFβ) 信号的调节。TGFβ 可分为两个分支，即激活素和骨形态发生蛋白 (BMP) 途径。在黑腹果蝇中，BMP 信号对于 JH 合成至关重要，而激活素信号则是产生进入变态所需的大脉冲 20E 的必要条件。然而，这些信号的作用在多大程度上保守仍不清楚。在这里，我们研究了蜕皮甾酮途径中的一个激活素成分 Smad 对 X（Smox）在后胚胎发育中在一种落叶瓢虫 Henosepilachna vigintioctopunctata 中的作用。RNA 干扰 (RNAi) 辅助的 Hvsmox 敲低抑制了幼虫生长，并损害了幼虫发育。所有 Hvmyo RNAi 幼虫都停留在第四龄幼虫阶段。此外，Hvsmox 的敲低延迟了肠道和马氏管的重塑。此外，JH 生物合成基因 (Hvjhamt)、JH 受体基因 HvMet 和 JH 反应基因 HvKr-h1 的表达大大增强。相反，蜕皮甾酮生成基因 (Hvspo)、20E 受体基因 (HvEcR) 和六个 20E 反应基因 (HvBrC、HvE74、HvE75、HvE93、HvHR3 和 HvHR4) 的表达水平显著降低。HvMet 的敲低部分恢复了 Hvsmox RNAi 甲虫的负表型。我们的结果表明，Smox 在 JH 产生、蜕皮甾酮生成和器官重塑中发挥调节作用，从而有助于调节 H. vigintioctopunctata 幼虫-蛹-成虫的转化。
