Development of green nematicides targeting a repressor of gonad mitosis in Bursaphelenchus xylophilus.

BACKGROUND

Bursaphelenchus xylophilus is a worldwide quarantine pest that causes serious damage to the ecological security of pine trees worldwide. However, the mechanisms involved in mitosis and gamete formation of B. xylophilus have not been reported.

METHODS

The expression of Bxy-fbf was determined by qRT-PCR and in situ hybridization. RNA interference technology is used to elucidate the biological function of Bxy-fbf. Furthermore, based on the structure of the BXY-FBF protein, lead compounds were identified through molecular docking and computer-aided drug design (CADD), and the efficacy of the two highest-scoring compounds was tested.

RESULTS

In this study, the qPCR results showed that the expression of Bxy-fbf was highest in the female adult of B. xylophilus. The Bxy-fbf is widely expressed throughout the body of B. xylophilus during the embryonic stage. In the J2 to adult stages, it is mainly expressed centrally near the mitotic zone, spermathecae and oocysts. The RNAi results revealed that mitosis region of interference group was significantly longer than that of the control group, while the number of gametes was significantly less than that of the control group. The sperm area of the interference group is significantly bigger than that of the control group. Molecular docking and computer-aided drug design (CADD) were performed on the BXY-FBF protein, and five compounds (P635-0358, C776-1628, 6383-0918, Y021-7698 and 8017-1200) were screened. The two drugs with the highest scores were tested, and it was found that the nematodes that had been immersed in the drugs consumed fungi at a slower rate than the control group.