Key Laboratory of Bio-Pesticide Innovation and Application of Guangdong Province, South China Agricultural University, Guangzhou, China.
MS Swaminathan School of Agriculture, Centurion University of Technology and Management, Paralakhemundi, India.
Pest Manag Sci. 2022 Sep;78(9):3859-3870. doi: 10.1002/ps.6980. Epub 2022 May 21.
Tyrosine hydroxylase (TH), a melanin synthesis pathway enzyme hydroxylating tyrosine into 3,4-dihydroxyphenylalanine, is involved in the pigmentation and sclerotization of insect cuticles. However, the role of TH in 28-spotted potato ladybeetle (Henosepilachna vigintioctopunctata), an emerging pest of the solanaceous crops has been explored to a limited extent. In this study, we integrated dietary RNA interference (RNAi) and hematoxylin and eosin (H&E) staining with various bioassays to analyze the role of tyrosine hydroxylase (HvTH) throughout the developmental processes of Henosepilachna vigintioctopunctata.
The results revealed that ingestion of dsHvTH led to cuticle tanning impairment, arrested larval feeding in the first and second instars of Henosepilachna vigintioctopunctata, and subsequently resulted in 100% mortality. The H&E staining assays revealed that dsHvTH prevented new abdominal cuticle formation. A pharmacological study using 3-iodo-tyrosine (3-IT), a HvTH inhibitor, disrupted larval-larval-pupal cuticle tanning during the third-fourth instar larval development and eventually failed to pupate. Similarly, dsHvTH fed to fourth instars hindered larval-pupal-adult cuticle tanning, and the eclose adults were 100% malformed. Ingestion of dsHvTH or 3-IT significantly down-regulated HvTH, HvDDC, Hvebony, and Hvlaccase2 expression and reduced dopamine levels. Finally, HvTH silencing in adult females substantially reduced the offspring hatching rates.
The collective results of the study suggested that HvTH plays conserved roles in larval-pupal-adult cuticle melanization and sclerotization while exhibiting a novel function in Henosepilachna vigintioctopunctata reproduction. © 2022 Society of Chemical Industry.
酪氨酸羟化酶（TH）是一种黑色素合成途径的酶，它将酪氨酸羟基化为 3,4-二羟基苯丙氨酸，参与昆虫表皮的色素沉着和硬化。然而，TH 在 28 点马铃薯瓢虫（Henosepilachna vigintioctopunctata）中的作用，一种新兴的茄科作物害虫，仅在有限的程度上得到了探索。在这项研究中，我们综合了饮食 RNA 干扰（RNAi）和苏木精和伊红（H&E）染色与各种生物测定，以分析酪氨酸羟化酶（HvTH）在 Henosepilachna vigintioctopunctata 整个发育过程中的作用。
结果表明，摄入 dsHvTH 导致角质层鞣制受损，阻止 Henosepilachna vigintioctopunctata 的第一和第二龄幼虫进食，随后导致 100%死亡。H&E 染色分析表明，dsHvTH 阻止了新的腹部角质层形成。使用 HvTH 抑制剂 3-碘酪氨酸（3-IT）的药理学研究破坏了第三至第四龄幼虫发育过程中的幼虫-幼虫-蛹角质层鞣制，最终未能化蛹。同样，dsHvTH 喂食第四龄幼虫会阻碍幼虫-蛹-成虫角质层鞣制，羽化的成虫 100%畸形。摄入 dsHvTH 或 3-IT 显著下调了 HvTH、HvDDC、Hvebony 和 Hvlaccase2 的表达，并降低了多巴胺水平。最后，成年雌虫 HvTH 沉默显著降低了后代的孵化率。
该研究的综合结果表明，HvTH 在幼虫-蛹-成虫表皮黑色素沉着和硬化中发挥保守作用，同时在 Henosepilachna vigintioctopunctata 繁殖中表现出一种新的功能。© 2022 化学工业协会。
