Cloning and characterization of Methoprene ‐tolerant (Met) and Krüppel homolog 1 (Kr‐h1) genes in the wheat blossom midge, Sitodiplosis mosellana

AbstractJuvenile hormone (JH), a growth regulator, inhibits ecdysteroid ‐induced metamorphosis and controls insect development and diapause. Methoprene‐tolerant (Met) and Krüppel homolog 1 (Kr‐h1) are two proteins involved in JH action. To gain some insight into their function in development ofSitodiplosis mosellana, an insect pest undergoing obligatory larval diapause at the mature 3rd instar stage, we cloned full ‐length complementary DNAs ofMet andKr ‐h1 from this species. SmMet encoded a putative protein, which contained three domains typical of the bHLH ‐PAS family and eight conserved amino acid residues important for JH binding. SmKr‐h1 encoded a protein showing high sequence homology to its counterparts in other species, and contained all eight highly conserved Zn‐finger motifs for DNA‐binding. Expression patterns ofSmMet andSmKr ‐h1 were developmentally regulated and JH III responsive as well. Their mRNA abundance increased as larvae entered early 3rd instar, pre ‐diapause and maintenance stages, and peaked during post‐diapause quiescence, a pattern correlated with JH titers in this species. Different from reduced expression ofSmMet,SmKr ‐h1 mRNA increased at mid ‐to‐late period of post‐diapause development. Topical application of JH III on diapausing larvae also induced the two genes in a dose‐dependent manner. Expression ofSmMet andSmKr ‐h1 clearly declined in the pre ‐pupal phase, and was significantly higher in female adults ...
Source: Insect Science - Category: Biology Authors: Tags: ORIGINAL ARTICLE Source Type: research