Functional Study Of Methoprene-Tolerant In Reproduction And Diapause Of The Cabbage Beetle Colaphellus Bowringi

Juvenile hormone(JH) can promotes reproduction, and the absence of JH leads to diapause in adult. It showed that JH may play an important role in the antagonism between reproduction and diapause. However, the mechanism of action of JH research is uncovered. Colaphellus bowringi Bay is a facuitative diapause and vegetable pest. At 25℃, under long-day conditions, C. bowringi was induced to diapause-destined individual, under short-day conditions, C. bowringi was induced to nondiapause-destined individual. It was diapauses preparatory period which four days feeding period of adult post eclosion to diapauses. The ovary of diapause-destined individual was not developing and no yolk deposition, the fat body was developing well and filling the whole abdomen in the diapause preparatory period. However the ovary of nondiapause-destined individual was developing well and much more yolk deposition, the fat body was sparse. The study use C. bowringi as experimental subjects and combine with RNAi technology to study the functional of Methoprene-tolerant(Met) in reproduction and diapause in C. bowringi. The main results are as follows: 1. The function of JH in ovarian development and lipid accumulation of C. bowringiDiapause-destined individual were injected 15 μg JH analog Methoprene. The ovary of individual had developed and similar to nondiapause-destined individual. Meanwhile, compared with the control, expression of Vg genes is significantly higher and lipid signal weakened and relative lipid content decreased on fat body after injecting Methoprene. 2. Cloning and sequence analysis of Met geneThe study had got sequence information of Met gene from the transcriptome database of C. bowringi. With primers were designed based on the sequence, by cloning, splicing and sequencing, the study has obtained the full-length cDNA of Met1 and Met2, full-length cDNA were 2045 bp, 2044 bp. Using Expasy transcription software for protein functional domain analysis found that both Met only N-terminal 20 amino acids differ, suggesting that two kinds Met gene function may be similar. By NCBI BLAST function and build phylogenetic tree of the Met was found that the two Met belong to a branch, and with Met of Tribolium castaneum is high affinity. 3. Function of Met in reproduction and diapause of C. bowringiDiapause-destined individual was interferenced Met and injected JH analogs by RNAi technology. Relative expression of Vg1 and Vg2 were significantly lower than the control group. Nondiapause-destined individual appear developmental state which similar to diapause individual after interferencing Met, including the development of ovarian was suppressed, lipid signal weakened and relative lipid content decreased on fat body, relative expression of Fas, Hsp23 and Hsp27 significantly increased compared to the control group, but relative expression of Foxo and Hsp21 was no significant difference compared to control group.The study showed that JH via Met induces Vg expression and ovarian development to promote reproduction and inhibits lipid storage and stress resistance to rejct the occurrence of diapauses. This work provides clues and evidence for the mechanism of JH signaling pathway.