Ze Long-Ji, Jin Lin, Li Guo-Qing
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, China.
Front Physiol. 2022 Feb 24;13:829675. doi: 10.3389/fphys.2022.829675. eCollection 2022.
N-β-alanyldopamine (NBAD) is a precursor of N-acylquinone sclerotin utilized for cross-linking between cuticular proteins for cuticle during insect molting. The importance of NBAD in cuticle tanning has not been well compared among different developing stages of insects. , a typical polyphagous pest feeding on a large number of Solanaceae and Cucurbitaceae plants in Asian countries, displays diverse cuticle pigmentation patterns among developing stages and body regions. Here, we found that the expression of three genes (, , and ) involved in NBAD biosynthesis peaked in the 4-day-old pupae or 0-day-old adults of . At the first, second, third, and fourth larval instar and pupal stage, their transcript levels were high just before and/or right after the molting. Moreover, they were more abundantly transcribed at the larval heads than in the bodies. RNA interference (RNAi) of either or at the third instar larvae selectively deepened the color of the larval head capsules, antennae, mouthpart, scoli, strumae, and legs; and depletion of the two genes blackened the pupal head capsules, antennae, mouthpart, and legs. However, the knockdown of either or darkened the whole bodies of the adults. Conversely, RNAi of at the third instar stage had little influence on the pigmentation in the larvae, pupae, and adults. These findings demonstrated that Adc and Ebony are important in cuticle pigmentation of and suggested that larger quantities of NBAD were present in adults and play more important roles in pigmentation than larvae/pupae.
N-β-丙氨酰多巴胺（NBAD）是N-酰基醌鞣化蛋白的前体，用于昆虫蜕皮期间表皮蛋白之间的交联，以形成表皮。NBAD在表皮鞣化中的重要性在昆虫的不同发育阶段尚未得到充分比较。烟粉虱是一种典型的多食性害虫，在亚洲国家以大量茄科和葫芦科植物为食，在发育阶段和身体部位表现出不同的表皮色素沉着模式。在这里，我们发现参与NBAD生物合成的三个基因（Adc、Ebony和Tan）的表达在4日龄蛹或0日龄成虫中达到峰值。在一龄、二龄、三龄和四龄幼虫以及蛹期，它们的转录水平在蜕皮前和/或蜕皮后很高。此外，它们在幼虫头部的转录比身体中更丰富。在三龄幼虫期对Adc或Ebony进行RNA干扰（RNAi）会选择性地加深幼虫头部胶囊、触角、口器、瘤、瘤突和腿部的颜色；敲除这两个基因会使蛹的头部胶囊、触角、口器和腿部变黑。然而，敲除Tan或Ebony会使成虫的全身变黑。相反，在三龄期对Adc进行RNAi对幼虫、蛹和成虫的色素沉着影响很小。这些发现表明，Adc和Ebony在烟粉虱的表皮色素沉着中很重要，并表明成虫中存在更多的NBAD，并且在色素沉着中比幼虫/蛹发挥更重要的作用。
