Molecular characterization and functional analysis of glutathione S-transferase genes of pine wood nematode (Bursaphelenchus xylophilus) for avermectin.

Pine wilt disease (PWD), caused by Bursaphelenchus xylophilus (pine wood nematodes, PWNs), is a forest disease that seriously threatens the health of Pinus forestry. Glutathione S-transferases (GSTs) play important roles in xenobiotic metabolism, lipophilic compound transport, antioxidative stress reactions, anti-mutagenesis, and antitumor activity. The analysis and investigation of the specific functions of GSTs in the metabolism of toxic substances in nematodes are important for identifying potential target genes to control the spread and transmission of B. xylophilus. In this study, 51 Bx-GSTs were found in the genome of B. xylophilus. Two key Bx-gsts (Bx-gst12 and Bx-gst40) were analyzed when B. xylophilus was exposed to avermectin. The expression of Bx-gst12 and Bx-gst40 was significantly increased when B. xylophilus was exposed to 1.6 and 3.0 mg/mL avermectin solutions. Notably, combined silencing of both Bx-gst12 and Bx-gst40 did not further increase the mortality rates under avermectin exposure. Mortality rates were significantly increased in nematodes treated with dsRNA compared to control nematodes (p < 0.05) after RNAi. The feeding ability of nematodes was also significantly reduced after treatment with dsRNA. These results suggested that Bx-gsts are associated with the detoxification process and feeding behavior of B. xylophilus. Silencing Bx-gsts leads to increased susceptibility to nematicides and reduces the feeding ability of B. xylophilus. Therefore, Bx-gsts will be a new control target of PWNs in the future.