Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
Int J Mol Sci. 2022 Jun 9;23(12):6431. doi: 10.3390/ijms23126431.
The rhizospheric bacterium Pf-5 can colonize the seed and root surfaces of plants, and can protect them from pathogen infection. Secondary metabolites, including lipopeptides and polyketides produced by Pf-5, are involved in its biocontrol activity. We isolated a crude extract from Pf-5. It exhibited significant surface activity and strong antibacterial activity against DZ-12, which causes maize brown rot on leaves. HPLC analysis combined with activity tests showed that the polyketide pyoluteorin in the crude extract participated in the suppression of DZ-12 growth, and that the lipopeptide orfamide A was the major biosurfactant in the crude extract. Further studies indicated that the pyoluteorin in the crude extract significantly suppressed the biofilm formation of DZ-12, and it induced the accumulation of reactive oxygen species in DZ-12 cells. Scanning electron microscopy and transmission electron microscopy observation revealed that the crude extract severely damaged the pathogen cells and caused cytoplasmic extravasations and hollowing of the cells. The pathogenicity of DZ-12 on maize leaves was significantly reduced by the crude extract from Pf-5 in a dose-dependent manner. The polyketide pyoluteorin had strong antibacterial activity against DZ-12, and it has the potential for development as an antimicrobial agent.
Pf-5 根际细菌可以定殖于植物种子和根表面，并保护它们免受病原体感染。Pf-5 产生的次生代谢物，包括脂肽和聚酮化合物，参与其生物防治活性。我们从 Pf-5 中分离出一种粗提取物。它表现出显著的表面活性和对导致玉米叶部褐斑病的 DZ-12 的强烈抗菌活性。HPLC 分析结合活性测试表明，粗提物中的聚酮类化合物 pyoluteorin 参与了对 DZ-12 生长的抑制，而粗提物中的脂肽 orfamide A 是主要的生物表面活性剂。进一步的研究表明，粗提物中的 pyoluteorin 显著抑制了 DZ-12 的生物膜形成，并诱导了 DZ-12 细胞中活性氧的积累。扫描电子显微镜和透射电子显微镜观察显示，粗提物严重破坏了病原菌细胞，导致细胞质渗出和细胞空化。Pf-5 的粗提物以剂量依赖的方式显著降低了 DZ-12 对玉米叶片的致病性。聚酮类化合物 pyoluteorin 对 DZ-12 具有强烈的抗菌活性，具有开发为抗菌剂的潜力。
