A chitinase gene (LmCht10) from Locusta migratoria: Biological functions and regulations during metamorphosis

We identified Locusta migratoria (L. migratoria) chitinase gene 10 (LmCht10) from a locust expressed sequence tag (EST) database and amplified the full-length cDNA sequence by RACE-PCR. The obtained LmCht10 cDNA fragment is 10258 bp containing an open reading frame (ORF) of 8895 bp encoded 2965 amino acids. LmCht10 contains five catalytic domains and six chitin binding domains (CBDs). Biological functions of LmCht10 were studied by RNA interference (RNAi), the results showed that the corresponding transcript level was reduced in the nymphs after LmCht10 dsRNA injection compared with the control insects; the nymphs injected with dsLmCht10 displayed slowly development, failed to detach from the old cuticle during molting process and died eventually; After adults were injected with dsLmCht10, the fecundity decreased significantly compared with control insects injected with dsGFP, about 30% eggs laid by females injected with dsLmCht10 appeared malformation or could not hatch. No difference was observed for males between control and treatment. Furthermore, we found LmCht10 was regulated by 20E and miRNA, respectively. These results suggested that LmCht10 is a large chitinase with multi-domains; LmCht10 plays an important role in the molting process and egg hatch of L. migratoria; Both 20E and miRNA can regulate the expression of LmCht10.