State Key Laboratory of Subtropical Silviculture, College of Forestry and Biotechnology, Zhejiang Agricultural & Forestry University, Hangzhou, China.
Natural Forest Protection Center, Liaoning Forestry and Grassland Bureau, Shenyang, China.
Pest Manag Sci. 2021 Jan;77(1):138-147. doi: 10.1002/ps.6001. Epub 2020 Aug 13.
Bursaphelenchus xylophilus is one of the most destructive invasive species, causing extensive economic losses worldwide. The sex ratio of female to male of B. xylophilus plays 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, in B. xylophilus.
Bxy-mab-3 has 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 mRNA in situ hybridization. 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 of Bxy-mab-3 had no effect on the sex ratio of B. xylophilus.
Bxy-mab-3 is indispensable for spermatogenesis, ontogenesis and mating behavior. It is a typical sex-determination gene with differential expression in males and females. However, knocking down Bxy-mab-3 expression could not alter the sex ratio as seen in other species. Our findings contribute towards a better understanding of the molecular events of Bxy-mab-3 in B. xylophilus, which provides promising hints for control of pine wilt disease by blocking ontogenesis and decreasing nematode fecundity.
松材线虫是最具破坏性的入侵物种之一，在全球范围内造成了广泛的经济损失。松材线虫的雌雄比例在线虫侵染中起着重要作用。然而，人们对其性别决定过程知之甚少。双性/ mab-3 相关家族的转录因子在动物中高度保守，在性别决定、精子发生和个体发生中起着至关重要的作用。因此，我们研究了松材线虫中的同源物 Bxy-mab-3。
Bxy-mab-3 具有两个典型的保守 DNA 结合结构域。在 J2（第二阶段的幼虫）、J3、J4 和雄性成虫（特别是在刺上）中观察到了 Bxy-mab-3，但在卵或雌性成虫中未观察到通过 mRNA 原位杂交。RNA-Seq 表明雄性中的表达显著更高。RNAi 显示，雄性成虫的体型和精子大小明显小于对照。同时，几乎所有经 RNAi 处理的雄性成虫都未能与正常雌性成虫交配，即使有 26.34%的干扰雄性成虫也没有产生精子。然而，Bxy-mab-3 的 RNAi 对松材线虫的性别比例没有影响。
Bxy-mab-3 对精子发生、个体发生和交配行为是不可或缺的。它是一个典型的性别决定基因，在雄性和雌性中的表达存在差异。然而，敲低 Bxy-mab-3 的表达并不能改变其他物种中所见的性别比例。我们的研究结果有助于更好地了解 Bxy-mab-3 在松材线虫中的分子事件，为通过阻断个体发生和减少线虫繁殖力来控制松材线虫病提供了有希望的线索。
