Abstract: 【Aim】 To explore the roles of Hsp90 gene in development and response to heat and cold stress in the citrus red mite, Panonychus citri. 【Methods】 The full-length cDNA encoding Hsp90 from P. citri was cloned and identified using RT-PCR and RACE technique. Bioinformatics programs were used to analyze the sequence characteristics of the gene. The mRNA expression levels of the gene in this mite at different developmental stages and under cold and heat stress conditions were detected by real-time PCR. 【Results】 The complete cDNA of the cloned gene PcHsp90 with GenBank accession no. GQ495086 is 212 763 bp in length, and contains an open reading frame of 2 193 bp, which encodes a protein of 730 amino acids, with the molecular weight of 83.85 kDa and the theoretical isoelectric point of 4.99. The deduced amino acid sequence contains five highly conserved motifs of Hsp90 family and the cytoplasmic Hsp90 C-terminal region “MEEVD”. Phylogenetic analysis showed that PcHsp90 clustered firstly with Hsp90 of Tetranychus cinnabarinus, and then with that of Ixodes scapularis, suggesting the close relationship among them. PcHsp90 transcripts were all detected at different developmental stages, and the relative mRNA expression level was significantly lower at larval stage than those at nymphal and adult stages (P=0.015). No distinct change was found in relative PcHsp90 mRNA expression levels in the mites subjected to 0-10℃ cold stress (P=0.492), but a significant up-regulation was observed in the mites subjected to 35-41℃ heat stress (P=0.007); especially when the temperature was up to 41℃, the mRNA level was 6.75-fold as high as that of the control (25℃).【Conclusion】 PcHsp90 may be involved in development and plays an important role in response to heat stress in P. citri.  

Key words: Panonychus citri, Hsp90, cDNA cloning, cold stress, heat stress, developmental stage, mRNA expression