Transcriptome Analysis of Beet Webworm Shows That Histone Deacetylase May Affect Diapause by Regulating Juvenile Hormone

SIMPLE SUMMARY: Diapause is a seasonal adaptation to stress in insects, including in Lepidoptera. Juvenile hormone (JH) is the key factor affecting larval diapause. The diapause of beet webworm, an important agricultural pest, is induced by photoperiod, but the mechanism is unknown. Transcriptome sequencing was performed in five different stages of beet webworm. The results showed that 393 genes in the red module were strongly related to JH, and the hub gene of the red module was histone deacetylase (HDAC). After injecting HDAC chemical inhibitors into beet webworms, we found that HDAC enzyme had an effect on JH content in beet webworms under photoperiod that induced diapause. Therefore, HDAC may be involved in diapause in beet webworms by altering JH levels. ABSTRACT: The beet webworm (Loxostege sticticalis L.) is an important agricultural pest and can tolerate harsh environmental conditions by entering diapause. The diapause mechanism of beet webworm is unknown. Therefore, we conducted a transcriptomic study of the process from diapause induction to diapause release in beet webworms. The results revealed 393 gene modules closely related to the diapause of beet webworm. The hub gene of the red module was the HDACI gene, which acts through histone deacetylase (HDAC) enzymes. HDAC enzyme activity was regulated by the light duration and influenced the JH content under induced beet webworm diapause conditions (12 h light:12 h dark). In addition, transcriptomic data suggested that circadian genes may not be the key genes responsible for beet webworm diapause. However, we showed that the photoperiod affects HDAC enzyme activity, and HDAC can regulate the involvement of JH in beet webworm diapause. This study provided a new module for studying insect diapause and links histone acetylation and diapause at the transcriptome level.