Root knot nematodes are the most devastating root pathogens, causing severe damage and serious economic losses to agriculture worldwide. Octanoic acid has been reported as one of the nematicides, and its mode of action is not fully understood. The main objective of this study was to elucidate the effect of octanoic acid on Meloidogyne incognita by transcriptomic analysis combined with physiological and biochemical assays. In the toxicity assays with octanoic acid, the threshold concentration with nematicidal activity and the maximum concentration to which nematodes could respond were 0.03 μL/mL and 0.08 μL/mL respectively. Microscopic observation combined with protein and carbohydrates assays confirmed that the structure of the second-stage juveniles (J2s) was severely disrupted after 72 h of immersion in octanoic acid. Transcriptome analysis has shown that octanoic acid can interfere with the nematode energy metabolism, lifespan and signaling. Although the effects are multifaceted, the findings strongly point to the cuticle, lysosomes, and extracellular regions and spaces as the primary targets for octanoic acid. In addition, nematodes can withstand the negative effects of low concentration of octanoic acid to some extent by up-regulating the defense enzyme system and heterologous metabolic pathways. These findings will help us to explore the nematicidal mechanism of octanoic acid and provide important target genes for the development of new nematicides in the future.

根结线虫是最具破坏性的根部病原体，给全球农业造成严重破坏和严重经济损失。辛酸已被报道为一种杀线虫剂，其作用方式尚不完全清楚。本研究的主要目的是阐明辛酸对南方根结线虫的影响通过转录组学分析结合生理和生化分析。在辛酸的毒性试验中，具有杀线虫活性的阈值浓度和线虫可以响应的最大浓度分别为 0.03 μL/mL 和 0.08 μL/mL。显微镜观察结合蛋白质和碳水化合物测定证实，在辛酸中浸泡 72 小时后，第二阶段幼体 (J2s) 的结构被严重破坏。转录组分析表明，辛酸可以干扰线虫的能量代谢、寿命和信号传导。尽管影响是多方面的，但研究结果强烈指出角质层、溶酶体和细胞外区域和空间是辛酸的主要目标。此外，线虫可以通过上调防御酶系统和异源代谢途径，在一定程度上抵御低浓度辛酸的负面影响。这些发现将有助于我们探索辛酸的杀线虫机制，为今后开发新型杀线虫剂提供重要的靶基因。