The use of Bacillus volatiles to manage root-knot nematodes (RKNs) is a topic that gained extensive attention because it is safe and environmentally benign. Bacillus velezensis TA-1, isolated from a continuously cropped soil, exhibited strong nematicidal activity against RKNs in vitro and in field conditions. However, it remains poorly understood whether TA-1 volatile organic compounds (VOCs) could be effective against Meloidogyne incognita. In this study, the results of chemotaxis activity test revealed that B. velezensis TA-1 exhibited strong repellent effects on second-stage juveniles (J2s) of M. incognita. In in vitro assays, TA-1 VOCs in a three-compartment Petri dish assay exhibited a mortality rate of 84.1% at 48 h and 92.8% at 72 h to M. incognita J2s. Further evidence revealed that TA-1 VOCs significantly inhibited the gene expression of mpk-1, flp-18 and ord-1 by 61.0%, 44.8% and 54.5%, respectively. Moreover, TA-1 VOCs increased the content of reactive oxygen species (ROS), resulting in severe oxidative stress and death of nematodes. Results from a double-layered greenhouse experiment indicated that the populations of J2s in the soil and in cucumber roots were notably reduced by TA-1 VOCs compared to the untreated control. Furthermore, eleven VOCs were identified from TA-1 by solid-phase microextraction gas chromatography-mass spectrometry (SPME-GC/MS) analysis, of which benzaldehyde, 2-decanol, and 2-undecanone had strong contact nematicidal activities against M. incognita J2s. In addition, benzaldehyde and 2-dodecanone exhibited fumigation effects on M. incognita J2s. Overall, these results demonstrated that TA-1 VOCs exhibited direct contact nematicidal and fumigation activities against RKNs and could be considered as potential biocontrol agents for the control of RKNs.

使用挥发性芽孢杆菌来控制根结线虫（RKN）是一个受到广泛关注的话题，因为它安全且对环境无害。从连作土壤中分离出来的贝莱斯芽孢杆菌TA-1 在体外和田间条件下均表现出针对 RKN 的强大杀线虫活性。然而，人们对 TA-1 挥发性有机化合物 (VOC) 是否能有效对抗南方根结线虫仍知之甚少。本研究的趋化活性测试结果表明， B. velezensis TA-1对南方根结线虫二期幼虫（J2s）具有较强的驱避作用。在体外测定中，TA-1 VOC 在三室培养皿测定中对南方根结线虫J2s 的死亡率在 48 小时时为 84.1%，在 72 小时时为 92.8%。进一步的证据表明，TA-1 VOCs 显着抑制mpk-1 、 flp-18和ord-1的基因表达，分别达 61.0%、44.8% 和 54.5%。此外，TA-1 VOCs增加了活性氧（ROS）的含量，导致线虫严重氧化应激和死亡。双层温室实验的结果表明，与未处理的对照相比，TA-1 VOC 显着减少了土壤和黄瓜根中 J2 的数量。此外，通过固相微萃取气相色谱-质谱（SPME-GC/MS）分析，从TA-1中鉴定出11种挥发性有机化合物，其中苯甲醛、2-癸醇和2-十一烷酮对南方根结线虫具有较强的接触杀线虫活性。 J2。此外，苯甲醛和2-十二酮对南方根结线虫J2s具有熏蒸作用。 总体而言，这些结果表明 TA-1 VOC 对 RKN 表现出直接接触杀线虫和熏蒸活性，可被视为控制 RKN 的潜在生物防治剂。