Molecular Characterization of Six Small Heat Shock Proteins and Their Responses Under Cadmium Stress in Oxya chinensis (Orthoptera: Acridoidea)

摘要

Small heat shock proteins (sHSPs) have been implicated in many physiological processes and play important roles in the response to various stresses. In this study, the full-length sequences of six sHSPs: OcHSP19.1, 19.8, 20.4, 20.7, 21.1, and 23.8 were obtained from the rice grasshopper Oxya chinensis transcriptome database. The deduced amino acid sequences of the six OcsHSPs contain a typical alpha-crystallin domain, which consists of approximately 100 amino acid residues and five beta-strands. The phylogenetic analysis suggested that OcHSP23.8 was orthologous to the sHSPs of other species and that OcHSP19.1, 20.4, 20.7, and 21.1 were species specific, whereas OcHSP19.8 did not cluster closely to Orthoptera but was placed on the basal end of the cluster. Developmental stage-dependent and tissue-specific expression patterns were evaluated using quantitative real-time polymerase chain reaction. The six genes were expressed in all developmental stages and showed clear tissue specificity. The cadmium acute experiment indicates that Cd2(+) can induce the six genes. However, various response patterns were observed among these genes under Cd2+ stress conditions. OcHSP19.1, 19.8, 20.4, and 20.7 were highly induced by 2.61mM Cd2+ at 24 h. OcHSP23.8 was significantly upregulated by 2.61mM Cd2+ at 6 h. For OcHSP21.1, the highest expression levels were found after treatment with 0.87 mM Cd2+ for 24 h, 1.74mM Cd2+ for 36 h, and 2.61mM Cd2+ for 12 h. These differential characteristics will facilitate future investigations into the physiological functions of sHSPs.