A heat shock 70kDa protein MaltHSP70-2 contributes to thermal resistance in Monochamus alternatus (Coleoptera: Cerambycidae): quantification, localization, and functional analysis

Abstract

Abstract Background Heat Shock Proteins 70 (HSP70s) in insects act on a diverse range of substrates to assist with overcoming extreme high temperatures. MaltHSP70-2, a member of HSP70s, has been characterized to involve in the thermotolerance of Monochamus alternatus in vitro, while quantification and localization of MaltHSP70-2 in various tissues and its functional analysis in vivo remain unclear. Results In this study, temporal expression of MaltHSP70-2 indicated a long-last inductive effect on MaltHSP70-2 expression maintained 48 hours after heat shock. MaltHSP70-2 showed a global response to heat exposure which occurring in various tissues of both males and females. Particularly in the reproductive tissues, we further performed the quantification and localization of MaltHSP70-2 protein using Western Blot and Immunohistochemistry, suggesting that enriched MaltHSP70-2 in the testis (specifically in the primary spermatocyte) must be indispensable to protect the reproductive activities (e.g., spermatogenesis) against high temperatures. Furthermore, silencing MaltHSP70-2 markedly influenced the expression of other HSP genes and thermotolerance of adults in bioassays, which implied a possible interaction of MaltHSP70-2 with other HSP genes and its role in thermal resistance of M. alternatus adults. Conclusions These findings shed new insights into thermo-resistant mechanism of M. alternatus to cope with global warming from the perspective of HSP70s functions.