Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, PR China.
Phytopathology. 2018 Dec;108(12):1373-1385. doi: 10.1094/PHYTO-04-18-0118-R. Epub 2018 Oct 31.
To develop an effective biological agent to control Sclerotinia sclerotiorum, three endophytic Bacillus spp. strains with high antagonistic activity were isolated from maize seed and characterized. In vitro assays revealed that the Bacillus endophytes could produce volatile organic compounds (VOC) that reduced sclerotial production and inhibited mycelial growth of S. sclerotiorum. Gas chromatography-mass spectrometry revealed that the selected strains produced 16 detectable VOC. Eight of the produced VOC exhibited negative effects on S. sclerotiorum, while a further four induced accumulation of reactive oxygen species in mycelial cells. A mixture of VOC produced by Bacillus velezensis VM11 caused morphological changes in the ultrastructure and organelle membranes of S. sclerotiorum mycelial cells. The bromophenol blue assay revealed a yellow color of untreated fungal mycelium, which grew faster and deeper from 24 to 72 h postinoculation, as an indication of reduced pH. The potassium permanganate (KMnO) titration assay showed that the rate of oxalic acid accumulation was higher in minimal salt liquid medium cultures inoculated with untreated fungal plugs compared with the Bacillus VOC-treated ones. Interestingly, biological control assays using host-plant leaves challenged with treated fungal mycelial plugs produced reduced lesions compared with the control. These findings provide new viable possibilities of controlling diseases caused by S. sclerotiorum using VOC produced by Bacillus endophytes.
为了开发有效的生物制剂来防治核盘菌，我们从玉米种子中分离出了 3 株具有高拮抗活性的内生芽孢杆菌菌株，并对其进行了特性分析。体外试验表明，这些内生芽孢杆菌能够产生挥发性有机化合物（VOC），从而减少菌核的产生并抑制核盘菌的菌丝生长。气相色谱-质谱联用分析显示，所选菌株共产生了 16 种可检测到的 VOC。其中 8 种 VOC 对核盘菌表现出负效应，而另外 4 种则诱导菌丝细胞中活性氧物质的积累。蜡状芽孢杆菌 VM11 产生的 VOC 混合物导致核盘菌菌丝细胞的超微结构和细胞器膜发生形态变化。溴酚蓝法显示，未经处理的真菌菌丝呈黄色，在接种后 24 至 72 小时内生长更快、更深，表明 pH 值降低。高锰酸钾（KMnO）滴定法显示，与未经 VOC 处理的真菌塞相比，在最小盐液体培养基中接种时草酸的积累速度更高。有趣的是，使用经处理的真菌菌丝塞处理宿主植物叶片的生物防治试验表明，与对照相比，处理过的叶片产生的病变明显减少。这些发现为利用内生芽孢杆菌产生的 VOC 来防治由核盘菌引起的疾病提供了新的可行方案。
