Abstract：
Epichloë endophytes, fungal endosymbionts of Pooidae grasses, are commonly utilized in forage and turf industries because they produce beneficial metabolites that enhance resistance against environmental stressors such as insect feeding and disease caused by phytopathogen infection. In pastoral agriculture, phytopathogenic diseases impact both pasture quality and animal production. Recently, bioactive endophyte strains have been reported to secrete compounds that significantly inhibit the growth of phytopathogenic fungi in vitro. A screen of previously described Epichloë-produced antifeedant and toxic alkaloids determined that the antifungal bioactivity observed is not due to the production of these known metabolites, and so there is a need for methods to identify new bioactive metabolites. The process described here is applicable more generally for the identification of antifungals in new endophytes. This study aims to characterize the fungicidal potential of novel, \'animal friendly\' Epichloë endophyte strains NEA12 and NEA23 that exhibit strong antifungal activity using an in vitro assay. Bioassay-guided fractionation, followed by metabolite analysis, identified 61 metabolites that, either singly or in combination, are responsible for the observed bioactivity. Analysis of the perennial ryegrass-endophyte symbiota confirmed that NEA12 and NEA23 produce the prospective antifungal metabolites in symbiotic association and thus are candidates for compounds that promote disease resistance in planta. The \"known unknown\" suite of antifungal metabolites identified in this study are potential biomarkers for the selection of strains that enhance pasture and turf production through better disease control.
摘要：
Epichloe内生菌，Pooidae草的真菌内共生体，通常用于牧草和草皮工业，因为它们产生有益的代谢物，可增强对环境应激源的抵抗力，例如昆虫摄食和由植物病原体感染引起的疾病。在牧区农业中，植物病原性疾病会影响牧场质量和动物生产。最近,据报道，生物活性内生菌菌株分泌的化合物在体外显着抑制植物病原真菌的生长。对先前描述的Epichloe产生的拒食剂和有毒生物碱的筛选确定，观察到的抗真菌生物活性不是由于这些已知代谢物的产生，因此需要鉴定新的生物活性代谢物的方法。这里描述的方法更普遍地适用于鉴定新内生菌中的抗真菌剂。本研究旨在表征新颖的杀菌潜力，\'动物友好\'Epichloe内生菌菌株NEA12和NEA23使用体外试验表现出强的抗真菌活性。生物测定指导的分馏，接下来是代谢物分析，鉴定出61种代谢物，单独或组合，负责观察到的生物活性。对多年生黑麦草-内生菌共生体的分析证实，NEA12和NEA23在共生关系中产生预期的抗真菌代谢产物，因此是促进植物抗病性的化合物的候选化合物。这项研究中确定的“已知未知”抗真菌代谢物套件是潜在的生物标志物，用于选择通过更好的疾病控制来提高牧场和草皮产量的菌株。
