Cloning and expression of the nuclear transcription factor SlβFTZ‐F1 cDNA from Spodoptera litura

Abstract Insect molting and metamorphosis are regulated by 20‐hydroxyecdysone, which activates the ecdysone receptors, followed by expression of a series of transcription factors. Beta Fushi Tarazu‐Factor 1 (βFTZ‐F1) is one of these ecdysis‐related early‐expressed transcription factors. A βFTZ‐F1 complementary DNA (cDNA) was cloned from Spodoptera litura. The full‐length cDNA was 2 194 bp in length and the open reading frame of SlβFTZ‐F1 cDNA consisted of 1 659 bp and encoded a 552‐amino acid protein with a molecular mass of 61.4 kDa. Homology analysis revealed that SlβFTZ‐F1 protein shared high identities to its homologues from other species. The A/B domains and the D domains were diverse among the insect βFTZ‐F1 proteins, but DNA binding domains (C domain) and the ligand binding domains (E domain) were highly conserved. Northern blot analysis detected a transcript of 2.2 kb in the epidermis of fifth to sixth molting larvae. Reverse transcription polymerase chain reaction revealed that SlβFTZ‐F1 gene started to increasingly and periodically express before each molt, followed by a decrease during the intermolt stages.