Identification of heat shock protein genes hsp70s and hsc70 and their associated mRNA expression under heat stress in insecticide-resistant and susceptible diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae)

Abstract

To gain further insight into the molecular features of the ubiquitous Hsp70 family of conserved heat shock proteins, total nine full-length cDNA sequences of inducible hsp70s (Px-hsp69-1, -2a, -2b, -3, -4, Px-hsp72-1a, -1b, -2 and -3) and one constitutive hsc70 (Px-hsc70(C)) were isolated and characterized in the diamondback moth (DBM), Plutella xylostella, collected from Fuzhou, China. The nine Px-hsp70s cDNAs encoded the protein of between 629-669 amino acids with molecular weight ranging from 69.00-72.58 kDa and were derived from four hsp70 genes in the genome of DBM. The Px-hsc70(C) cDNA contained 1,953 bp of open reading frame (ORF), which produced a putative protein comprising 650 amino acids with a calculated molecular weight of 71.18 kDa. Whether in adults or larvae of chlorpyrifos-resistant (RR) and chlorpyrifos-susceptible (SS) strains of DBM, the basal level (at 25°C) of Px-hsc70(C) mRNA expression was high, but no significant up-regulation expression was found under heat stress. However, heat stress facilitated up-regulation expressions of Px-hsp70s, and SS DBM displayed higher up-regulation expression of Px-hsp70s than RR DBM. We suggest that higher up-regulation expression of Px-hsp70s in SS DBM is probably involved in their higher thermal tolerance.

Keywords

• lepidoptera
• plutellidae
• plutella xylostella
• heat shock protein genes
• hsp70
• fitness
• chlorpyrifos-resistant
• chlorpyrifos-susceptible
• diamondback moth