杀鱼假交替单胞菌P3胞外产物抗紫菜腐霉机制及其对紫菜赤腐病防治效果评价

Extracellular products of Pseudoalteromonas piscicida P3: mechanism of inhibiting Pythium porphyrae and control effect on red rot disease of Neopyropia yezoensis

摘要:

【背景】赤腐病是由紫菜腐霉(Pythium chondricola/porphyrae)引起的紫菜栽培期最主要病害，而现有的防治方法效果有限。【目的】提取杀鱼假交替单胞菌(Pseudoalteromonas piscicida) P3的抗菌成分，探究其抑制紫菜腐霉的机制及对赤腐病的防治效果。【方法】有机溶剂萃取法从无菌上清液(cell-free supernatant, CFS)中提取抗菌物质，纸片扩散法及含毒介质法评价提取物对紫菜腐霉抑制效果；在紫菜腐霉侵染前、后添加提取物评价其防治效果；转录水平分析处理后的紫菜腐霉基因表达差异。【结果】拮抗菌P3乙酸乙酯提取物抑制紫菜腐霉效果最佳，处理后紫菜腐霉菌丝表现为生长量下降、细胞壁弯曲变薄、细胞基质流失、出现藏卵器等；在紫菜腐霉侵染前、后分别添加终浓度为15 mg/L的提取物，病斑抑制率分别为96.64%和85.06%；转录组分析显示紫菜腐霉在细胞质、膜、磷脂酰肌醇等通路基因下调。【结论】菌株P3的胞外产物对紫菜腐霉有显著抑制效果，并且有效防治紫菜赤腐病，为赤腐病的新型防治技术和药物开发提供了支持。

Abstract:

[Background] Red rot disease, caused by Pythium chondricola/porphyrae, is a major disease occurring in the cultivation of Neopyropia yezoensis, whereas the current control methods have limited control effects on this disease. [Objective] To extract the extracellular products of Pseudoalteromonas piscicida P3, investigate the mechanism of inhibiting P. porphyrae, and evaluate the control effect of the extracellular products on red rot disease. [Methods] Organic solvents were used to extract antimicrobial components from the cell-free supernatant (CFS). The disc diffusion method and dual culture bioassays were employed to evaluate the inhibitory effect of the extract on P. porphyrae. We then evaluated the control effect of the extract on red rot disease by adding it before and after P. porphyrae infection. The differences in gene expression of P. porphyrae after treatment were analyzed at the transcriptional level. [Results] The ethyl acetate extract of P3 exhibited the strongest inhibitory effect on P. porphyrae. The treatment with the extract resulted in decreased biomass, curved and thinned cell walls, loss of cellular contents, and oogonium appearance of P. porphyrae. The extract added at a final concentration of 15 mg/L before and after P. porphyrae infection demonstrated the inhibition rates of 96.64% and 85.06%, respectively. Transcriptome analysis revealed downregulation of the genes in pathways related to the cytoplasm, membrane, and phosphatidylinositol. [Conclusion] The extracellular products of P3 have a significant inhibitory effect on P. porphyrae and effectively control red rot disease in N. yezoensis. The findings provide support for the development of new control techniques and agents for red rot disease.