The role ofmab-3in spermatogenesis and ontogenesis of pinewood nematode,Bursaphelenchus xylophilus

Background Bursaphelenchus xylophilusis one of the most destructive invasive species, causing extensive economic losses worldwide. The sex ratio of female to male ofB. xylophilusplays an important role in the nematode infestation. However, little is known about the processes of its sex determination. The double sex/mab-3-related family of transcription factors are highly conserved in animals, playing crucial roles in sex determination, spermatogenesis and ontogenesis. We therefore investigated its orthologue,Bxy-mab-3, inB. xylophilus. Results Bxy-mab-3has two typical conserved DNA-binding domains. It was observed in J2 (the second-stage of juveniles), J3, J4 and male adults (specifically on the spicules), but not in eggs or female adults via mRNAin situhybridization. RNA-Seq indicated significantly higher expression in males. RNAi showed that the body size and sperm size of male adults were markedly smaller than those of the controls. Meanwhile, almost all the RNAi-treated males failed to mate with the normal females, even 26.34% of interfered males did not produce sperm. However, RNAi ofBxy-mab-3had no effect on the sex ratio ofB. xylophilus. Conclusion Bxy-mab-3is indispensable for spermatogenesis, ontogenesis and mating behavior. It is a typical sex-determination gene with differential expression in males and females. However, knocking downBxy-mab-3expression could not alter the sex ratio as seen in other species. Our findings contribute towards a better understanding of the molecular events ofBxy-mab-3inB. xylophilus, which provides promising hints for control of pine wilt disease by blocking ontogenesis and decreasing nematode fecundity.

Automated summary

Bxy-mab-3 gene is essential for spermatogenesis, ontogenesis, and mating behavior in B. xylophilus, showing differential expression in males, but does not impact the sex ratio. This finding contributes to a better understanding of the molecular events of Bxy-mab-3 in B. xylophilus and provides potential insights for controlling pine wilt disease.