Fernando Krishni, Reddy Priyanka, Hettiarachchige Inoka K, Spangenberg German C, Rochfort Simone J, Guthridge Kathryn M
Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, 3083 Victoria, Australia.
School of Applied Systems Biology, La Trobe University, Bundoora, 3083 Victoria, Australia.
Microorganisms. 2020 Jun 24;8(6):955. doi: 10.3390/microorganisms8060955.
Asexual spp. fungal endophytes have been extensively studied for their functional secondary metabolite production. Historically, research mostly focused on understanding toxicity of endophyte-derived compounds on grazing livestock. However, endophyte-derived compounds also provide protection against invertebrate pests, disease, and other environmental stresses, which is important for ensuring yield and persistence of pastures. A preliminary screen of 30 strains using an in vitro dual culture bioassay identified 18 endophyte strains with antifungal activity. The novel strains NEA12, NEA21, and NEA23 were selected for further investigation as they are also known to produce alkaloids associated with protection against insect pests. Antifungal activity of selected endophyte strains was confirmed against three grass pathogens, sp., sp., and sp., using independent isolates in an in vitro bioassay. NEA21 and NEA23 showed potent activity against sp. and NEA12 showed moderate inhibition against all three pathogens. Crude extracts from liquid cultures of NEA12 and NEA23 also inhibited growth of the phytopathogens sp. and sp. and provided evidence that the compounds of interest are stable, constitutively expressed, and secreted. Comparative analysis of the in vitro and in planta metabolome of NEA12 and NEA23 using LCMS profile data revealed individual metabolites unique to each strain that are present in vitro and in planta. These compounds are the best candidates for the differential bioactivity observed for each strain. Novel endophyte strains show promise for endophyte-mediated control of phytopathogens impacting spp. pasture production and animal welfare.
无性型真菌内生菌因其功能性次生代谢产物的产生而受到广泛研究。从历史上看，研究主要集中在了解内生菌衍生化合物对放牧牲畜的毒性。然而，内生菌衍生的化合物还能提供针对无脊椎害虫、疾病和其他环境胁迫的保护，这对于确保牧场的产量和持久性很重要。使用体外双培养生物测定法对30个菌株进行的初步筛选鉴定出18个具有抗真菌活性的内生菌菌株。选择了新菌株NEA12、NEA21和NEA23进行进一步研究，因为它们也已知会产生与防治害虫相关的生物碱。使用独立分离株在体外生物测定中证实了所选内生菌菌株对三种禾本科病原菌（分别为……种、……种和……种）的抗真菌活性。NEA21和NEA23对……种显示出强效活性，而NEA12对所有三种病原菌均显示出中度抑制作用。NEA12和NEA23液体培养物的粗提物也抑制了植物病原菌……种和……种的生长，并提供了证据表明感兴趣的化合物是稳定的、组成型表达的且会分泌。使用LCMS谱数据对NEA12和NEA23的体外和植物体内代谢组进行比较分析，揭示了每个菌株特有的个体代谢物，这些代谢物存在于体外和植物体内。这些化合物是观察到的每个菌株差异生物活性的最佳候选物。新型内生菌菌株有望用于内生菌介导的对影响……种牧场生产和动物福利的植物病原菌的控制。
