Characterisation Of GSTs Genes From Dendroctonus Armandi And Their Response To Host Chemical Defence

Dendroctonus armandi, as the most harmful bark beetle to the natural forest ecosystem in the Northwest of China, invading healthy Pinus armandi aged more than thirty years in the pure and mixed forests in Qinling Mountains, has become a major obstacle to the sustainable development and ecological environment construction in Qinling Mountains forest ecological system. As the essential detoxifying enzymes in insect, Glutathione S-transferases(GSTs) play an important role in overcoming host defense, invasion and colonization. Therefore, by cloning and classifying the GSTs genes in D. armandi could we learn better about the detoxification mechanism. The study includes these aspects: analysis GSTs genes phylogeny; research the GSTs genes’ expression profiles in different adult stages; test the response of GSTs genes transcription levels for host allelochemicals. The main results are as follows:Nine GSTs genes were cloned. The genes were classified into epsilon, sigma, omega and theta classes and designated as DaGSTe1, DaGSTe4, DaGSTe5, DaGSTe6, DaGSTs1, DaGSTs2, DaGSTo1, DaGSTo2 and DaGSTt1. The amino acid sequence identity analysis revealed that DaGSTs shared more than 40% homology with GSTs genes in other insects from each class.The results showed that there were no significant differences between female and male at different stages of adults except DaGSTs2. The variety of DaGSTs’ expression levels was closely related with the chemical environment at each stage. It suggests that DaGSTs may play a role in overcoming multiple host defense.Epsilon GSTs had been less affected by feeding or starving, but the transcript levels were significantly lower than those untreated. Sigma GSTs were significantly upregulated in male after feeding, while theta GSTs were significant downregulated in both sex. In addition, no significant differences in the transcript level were found in omega GSTs after feeding or starving.The expression levels of epsilon GSTs were diversified after terpenoid treatment. Sigma and theta classes of GSTs were significantly upregulated under all kinds of stimulus treatment, whereas the transcript levels of omega GSTs changed little.In conclusion, different classes of DaGSTs had different functions. Epsilon GSTs had a diverse response model to different plant xenobiotics from different intake ways. Sigma GSTs were always overexpressed after intake of the plant xenobiotics. The transcript level of omega GSTs was relatively stable under different treatment. The results suggest that Da GSTs have some relationship with the detoxification of terpenoids produced by the host pine via regulating transcript level.