Characterization of Three Heat Shock Protein Genes in and Their Expression Patterns in Response to Temperature Stress and Pupal Diapause.

Heat shock protein 70 genes participate in obligatory pupal diapause in to survive unfavorable conditions. In this study, three full-length cDNAs of , and were identified, and their expression patterns in response to diapause and short-term temperature stresses were investigated. Summer and winter diapause were induced in the pupae and non-diapause individuals were used as a control. The pupae from each diapause group were subjected to either hot or cold conditions and the expression levels of the HSP genes were measured. Our results showed that up-regulation of and were detected both in summer and winter diapause, but not for . Under cold stress, and were upregulated in summer and winter diapause, while heat shock significantly induced upregulation of all three genes. In non-diapause pupae, none of the genes responded to cold or heat stress. Furthermore, we found that incubation at 39 ∘C for 30 min was the most sensitive heat stress condition for expression in summer diapause. On the other hand, the same temperature was effective for , , and expression in winter diapause. During summer diapause, expression of all three genes was upregulated in response to high-temperature acclimation at 31 ∘C, but only and b were upregulated when acclimated to a low temperature of 4 ∘C in winter diapause. These results suggest that the , , and respond differently to pupal diapause and temperature stress, and that is more sensitive to heat shock than to cold stress.