Response And Functional Analysis Of Agasicles Hygrophila Heat Shock Protein Genes To High Temperature Stress

Flea beetle(Agasicles hygrophila)is a successfully introduced natural enemy insect controlling Alternanthera philoxeroides in the world.Temperature adaptability of Flea beetle is inferior and the warming climate has affected its geographic distribution and controlling effect.Especially,the high temperature summer is the growing summit of A.philoxeroides,but the high temperature obviously inhibits the population of Flea beetle.Heat shock protein(HSP)gene is one of the genes closely associated with temperature change and it plays an important role in growth and development of cells,and expression and regulation of genes.Additionally,the induced expression of heat shock protein is also necessary on adaptability and survival of insects in extreme temperature.This paper mainly studies two scientific issues:what is the reason that the population of Flea beetle suddenly declined in the high temperature season?What is the relation between heat shock protein gene and high temperature tolerance,growth and development of Flea beetle?Based on ecological issues,effect of high temperature on growth and development of Flea beetle.The results showed that short periods of high temperature had obvious effect on development and propagation of Flea beetle.By evaluating high temperature tolerance of Flea beetle at different stages from the perspective of survival rate alone,the order of high temperature tolerance was found to be pupa>adult>1st instar larvae>3rd instar Larvae>2rd instar larvae>eggs.The hatching rates of eggs treated under 37.5? respectively for 1h and 3h were respectively 24.28%and 6.92%,which were significantly lower than that of 25? control(95.47%).The eggs treated under 37.5? for 5h could not be hatched,so 37.5?was surmised the tolerance limit of Flea beetleTo reveal the relationship between heat shock protein gene and beetle's high temperature tolerance and development,we cloned and identified 27 heat shock protein genes of beetle through transcriptome sequencing and further cloning,which included 1 Hsp90 gene,6 Hsp70 genes,1 Hsp60 gene,5 Hsp40 genes,14 sHsps genes.Phylogenetic analysis showed that all the heat shock protein family could be clustered by each.Using real-time quantitative PCR,27 HSP genes expression patterns under heat stress in the egg and different developmental stages were analyzed.The results showed that 22 genes in 27 HSP genes had induced peak temperature(Tpeak),37.5?;Tpeak of 3 HSP genes was 40?,Tpeak of 1 HSP genes was 42.5 ?,but the last 4 genes were largely induced to express at 37.5?.By research on relationship between 27 HSP genes and growth and development of the beetle,26 genes highly expressed in the egg and pupa stage but relatively lower in larvae and adults stages.The research illustrated that,the beetle's high temperature tolerance at egg stage might be the cause that its populations decreased in hot seasons;Tpeak of Flea beetle's shock protein gene could represent the extreme temperature of tolerance;heat shock protein gene was closely related to the beetle's growth and development,it could play an important regulated roles in the egg and pupae stage.