Effects of curcumin on the expression of chitinase genes from the carmine spider mite, Tetranychus cinnabarinus(Boisduval)

The mechanism of the curcumin(substance from plants) against Tetranychus cinnabarinus was elucidated. The six cDNA sequences of chitinases of Tetranychus cinnabarinus(TcCHTs) were cloned and analyzed. Quantitative RT-qPCR was used to detect the expression levels of the chitinase genes across different developmental stages of T. cinnabarinus. Then the effect of curcumin on the gene expression of TcCHTs was determined. The results indicated:The six CHTs cDNA sequences had different domains. These genes had predicted molecular weights of 60.80, 69.03, 104.32, 59.75, 45.63, and 49.05 kDa, respectively, and isoelectric points of 5.44, 8.65, 6.23, 6.07, 6.12 and 8.27, respectively. Quantitative RT-PCR results revealed that CHTs expression levels in larvaes and nymphs were higher than those in eggs and adults. After the nymph mites were exposed to curcumin for 24 h, the mRNA expression levels of TcCHTs significantly decreased. It is noteworthy that TcCHIT1 and TcCHT5 were more sensitive than others. The results indicated that one of the acaricidal mechanisms of curcumin might be inhibiting the activity of chitinase. By affecting the degradation of chitin, the epidermal degeneration was inhibited, which will lead to the damage of normal growth and development of the mites integument.