Identification of Potential Target Transcription Factor Genes Regulated by Kruppel Homolog 1 in Chilo suppressalis (Lepidoptera: Crambidae)1

Juvenile hormone (JH) is a major endocrine hormone that mediates development, metamorphosis, and reproduction in insects. It binds directly to its methoprene-tolerant receptor and recruits a heterodimer partner to form the JH-receptor complex that then activates a JH-inducible gene known as the Kruppel homolog 1 (Kr-h1). There is evidence that this gene is a downstream factor mediating both physiological and biochemical processes; however, the functional mechanism of Kr-h1 is largely unknown. Using the economically important rice (Oryza sativa L.) pest Chilo suppressalis (Walker) (Lepidoptera: Crambidae) as a model, we used a combination of RNA interference (RNAi), high-throughput RNA sequencing, and real-time quantitative polymerase chain reaction (RT-qPCR) to identify candidate transcription factor (TF) genes that are regulated by Kr-h1. RNAi knockdown of Krh1 identified the Zinc finger proteins, ZBTB, THAP, PAX, MYB, HSF, Homeobox, HMG, CSD, basic helix-loop-helix, STAT, RHD, and MBD families as regulated by Kr-h1. RT-qPCR confirmed the transcription levels of these putative TFs and indicated that knockdown of Kr-h1 can induce or suppress the expression of these proteins in C. suppressalis. These results provide the basic information required for in-depth research on the TFs regulated by Kr-h1 in C. suppressalis and other insects.