Monochamus alternatus Hope (Coleoptera: Cerambycidae) warrants attention as a dominant transmission vector of the pinewood nematode, and it exhibits tolerance to high temperature. Heat shock protein 70 (HSP70) family members, including inducible HSP70 and heat shock cognate protein 70 (HSC70), are major contributors to the molecular chaperone networks of insects under heat stress. In this regard, we specifically cloned and characterized three MaltHSP70s and three MaltHSC70s. Bioinformatics analysis on the deduced amino acid sequences showed these genes, having close genetic relationships with HSP70s of Coleopteran species, collectively shared conserved signature structures and ATPase domains. Subcellular localization prediction revealed the HSP70s of M. alternatus were located not only in the cytoplasm and endoplasmic reticulum but also in the nucleus and mitochondria. The transcript levels of MaltHSP70s and MaltHSC70s in each state were significantly upregulated by exposure to 35–50°C for early 3 h, while MaltHSP70s reached a peak after exposure to 45°C for 2–3 h in contrast to less-upregulated MaltHSC70s. In terms of MaltHSP70s, the expression threshold in females was lower than that in males. Also, both fat bodies and Malpighian tubules were the tissues most sensitive to heat stress in M. alternatus larvae. Lastly, the ATPase activity of recombinant MaltHSP70-2 in vitro remained stable at 25–40°C, and this recombinant availably enhanced the thermotolerance of Escherichia coli. Overall, our findings unraveled HSP70s might be the intrinsic mediators of the strong heat tolerance of M. alternatus due to their stabilized structure and bioactivity.

The deduced amino-acid sequences of 17 protein disulphide isomerase (PDI) and PDI-like cDNAs of wheat assigned to nine homoeologous groups were searched for conserved motives by comparison with characterized sequences in different protein databases. The wheat protein sequences encoded by genes of different homoelogous groups showed a high level of structural similarity with the corresponding protein sequences of other species clustering into the same phylogenetic group. The proteins of five groups (I–V) share two thioredoxin-like active domains and show structural similarities with the corresponding proteins of higher eukaryotes, whereas those of the remaining three groups (VI–VIII) contain a single thioredoxin-like active domain. The expression analysis of the nine non-homoeologous wheat genes, which was carried out by quantitative RT-PCR in developing caryopses and in seedlings subjected to temperature stresses, showed their constitutive although highly variable transcription rate. The comprehensive structural and transcriptional characterization of the PDI and PDI-like genes of wheat performed in this study represents a basis for future functional characterization of the PDI gene family in the hexaploid context of bread wheat.