Department of Phytopathology, Universidade Federal de Lavras, Lavras, Brazil.
Department of Phytosanitary Defense, CCR, Universidade Federal de Santa Maria, Santa Maria, Brazil.
Pest Manag Sci. 2022 Feb;78(2):722-732. doi: 10.1002/ps.6685. Epub 2021 Nov 8.
The combination of biocontrol agents is a desirable strategy to improve control efficacy against the root-knot nematode (RKN) Meloidogyne incognita under field conditions. However, strains compatibility is generally tested in vitro and incompatible combinations are normally not further examined in experiments in planta. Therefore, there is virtually no information on the performance of incompatible strains. In this study, we evaluated two Bacillus strains previously described as incompatible in vitro for effects on plant growth and suppression of M. incognita, pathogenic fungi and nematophagous fungi.
Strains BMH and INV were shown to be closely related to Bacillus velezensis. These strains, when applied individually, reduced the number of galls and eggs of M. incognita by more than 90% in tomato roots. When BMH and INV were combined (BMH + INV), RKN suppression and tomato shoot weight were lower compared to single-strain applications. Additionally, metabolites in cell-free supernatants and volatile organic compounds (VOCs) from strains BMH and INV had strong effects against the plant pathogens M. incognita, Fusarium oxysporum, Rhizoctonia solani and Sclerotium rolfsiii, but not against three species of nematophagous fungi. Although strain INV and the combination BMH + INV emitted fewer VOCs than strain BMH, they were still capable of killing second-stage juveniles of M. incognita.
Bacillus strains BMH and INV inhibited M. incognita and fungal pathogens, and promoted tomato growth. However, strain INV emitted fewer VOCs and the combination BMH + INV did not enhance the activity of the biocontrol strains against the RKN or their capacity to promote plant growth. © 2021 Society of Chemical Industry.
在田间条件下，将生物防治剂组合使用是提高防治根结线虫（RKN）南方根结线虫效果的理想策略。然而，通常在体外测试菌株的相容性，不兼容的组合在植物体内实验中通常不会进一步检查。因此，实际上没有关于不兼容菌株性能的信息。在这项研究中，我们评估了两种先前在体外描述为不兼容的芽孢杆菌菌株，以研究它们对植物生长和南方根结线虫、致病真菌和线虫捕食性真菌的抑制作用。
菌株 BMH 和 INV 被证明与枯草芽孢杆菌关系密切。这两种菌株单独使用时，可使番茄根系中的南方根结线虫根结和卵的数量减少 90%以上。当 BMH 和 INV 组合使用（BMH+INV）时，与单菌株处理相比，RKN 抑制率和番茄地上部鲜重降低。此外，来自 BMH 和 INV 的细胞外上清液代谢物和挥发性有机化合物（VOCs）对植物病原菌南方根结线虫、尖孢镰刀菌、立枯丝核菌和茄病镰刀菌具有很强的抑制作用，但对三种线虫捕食性真菌没有抑制作用。尽管菌株 INV 和组合 BMH+INV 比菌株 BMH 释放的 VOCs 更少，但它们仍然能够杀死南方根结线虫的第二龄幼虫。
芽孢杆菌菌株 BMH 和 INV 抑制了南方根结线虫和真菌病原体，促进了番茄的生长。然而，菌株 INV 释放的 VOCs 较少，组合 BMH+INV 并没有增强生物防治菌株对 RKN 的活性或促进植物生长的能力。© 2021 英国化学学会。
