Sex determination is a key developmental event in all organisms. The pathway that regulates sexual fate has been well characterized at the molecular level in the model free-living nematode Caenorhabditis elegans. This study aims to gain a preliminary understanding of sex-determining pathways in a plant-parasitic nematode Meloidogyne incognita, and the extent to which the roles of the sex determination genes are conserved in a hermaphrodite species, C. elegans, and plant-parasitic nematode species, M. incognita. In this study, we targeted two sex-determining orthologues, sdc-1 and tra-1 from M. incognita using RNA interference (RNAi). RNAi was performed by soaking second-stage juveniles of M. incognita in a solution containing dsRNA of either Mi-tra-1or Mi-sdc-1 or both. To determine the effect of RNAi of the target genes, the juveniles treated with the dsRNA were inoculated onto a susceptible cultivar of cowpea grown in a nutrient pouch at 28 °C for 5 weeks. The development of the nematodes was analyzed at different time points during the growth period and compared to untreated controls. Our results showed that neither Mi-sdc-1 nor Mi-tra-1 have a significant role in regulating sexual fate in M. incognita. However, the silencing of Mi-sdc-1 significantly delayed maturity to adult females but did not affect egg production in mature females. In contrast, the downregulation of Mi-tra-1 transcript resulted in a significant reduction in egg production in both single and combinatorial RNAi-treated nematodes. Our results indicate that M. incognita may have adopted a divergent function for Mi-sdc-1 and Mi-tra-1distinct from Caenorhabditis spp. However, Mi-tra-1 might have an essential role in female fecundity in M. incognita and is a promising dsRNA target for root-knot nematode (RKN) management using host-delivered RNAi.

性别决定是所有生物体的关键发育事件。在模型自由生活线虫秀丽隐杆线虫中，调节性命运的途径已在分子水平上得到很好的表征。本研究旨在初步了解植物寄生线虫南方根结线虫的性别决定途径，以及性别决定基因在雌雄同体物种、秀丽隐杆线虫和植物寄生线虫中的保守作用程度。种，M. incognita。在这项研究中，我们针对来自M. incognita 的两种性别决定直向同源物sdc-1和tra-1使用 RNA 干扰 (RNAi)。RNAi 是通过将南方根结线虫的第二阶段幼虫浸泡在含有Mi-tra-1或Mi-sdc-1或两者的dsRNA 的溶液中来进行的。为了确定靶基因 RNAi 的影响，将用 dsRNA 处理的幼虫接种到在 28°C 下在营养袋中生长的豇豆易感品种上 5 周。在生长期间的不同时间点分析线虫的发育，并与未处理的对照进行比较。我们的结果表明，Mi-sdc-1和Mi-tra-1在调节M. incognita 的性命运方面都没有显着作用。然而，Mi-sdc-1的沉默显着延迟成年雌性的成熟，但不影响成熟雌性的产蛋量。相比之下，Mi-tra-1转录本的下调导致单一和组合 RNAi 处理的线虫产蛋量显着减少。我们的结果表明M. incognita可能对Mi-sdc-1和Mi-tra-1采取了不同于Caenorhabditis spp 的不同功能。然而，Mi-tra-1可能在M. incognita 的雌性繁殖中发挥重要作用，并且是使用宿主提供的 RNAi 进行根结线虫 (RKN) 管理的有前途的 dsRNA 目标。