Battle in the dark - Interactions of the fungal pathogen Fusarium culmorum with beneficial microorganisms at the soil-root interface of wheat

美国明尼苏达大学圣保罗分校植物病理学系正在进行的这项研究，调查了真菌毒素脱氧雪腐镰刀菌醇（DON）在小麦根部感染真菌病原体镰刀菌中的作用。重点研究了F. culmorum、DON与有益根瘤菌链霉菌之间的相互作用。进一步分析了DON和F. culmorum对链霉菌的体外和植物抑制作用。本研究的第一阶段表明，除链霉菌外，荧光假单胞菌是小麦根系土传镰刀菌的强抑制剂，除culmorum外，graminearum是美国大平原上游小麦和大麦镰刀菌足和根腐病的主要病原体。因此，荧光假单胞菌和禾草假单胞菌分离株将被纳入长期的研究停留。从美国大平原上游的麦田中获得的有益根瘤菌（链霉菌和荧光假单胞菌）的碳利用，以及本研究中使用的不同镰刀菌种类和化学型，将使用不同的碳源和浓度作为底物，在微滴度试验中进行分析。这将有助于解释谷物中抑制性根瘤菌和土传病原体之间不同的拮抗相互作用。此外，还计划在田间条件下研究DON对小麦根茎基部成功侵染镰刀菌的影响。DON作为毒力因子对镰刀菌根侵染的影响也将在大麦上进行。在受控条件下的实验中，计划分析产毒镰刀菌感染后，霉菌毒素DON是否从茎基转移到大麦籽粒中，这可能是成熟大麦籽粒中霉菌毒素污染的另一个来源。

This ongoing study conducted at the Department of Plant Pathology, University of Minnesota, St. Paul, USA, investigates the role of the mycotoxin deoxynivalenol (DON) during root infections of wheat by the fungal pathogen Fusarium culmorum. The main focus is on the interaction between F. culmorum, DON and beneficial rhizobacteria, i.e. Streptomyces spp.. Further, the suppressive effect of DON and F. culmorum, respectively, to Streptomyces spp. is analysed in vitro and in planta. The first phase of this research suggested that besides Streptomyces spp. fluorescent Pseudomonas species are strong inhibitors of soilborne Fusarium species at wheat roots and that F. graminearum besides F. culmorum is a main contributor to Fusarium Foot and Root Rot of wheat and barley in the Upper Great Plains, USA. Therefore, fluorescent Pseudomonas and F. graminearum isolates will be included into the prolonged research stay. The carbon use of the obtained beneficial rhizobacteria (Streptomyces spp. and fluorescent Pseudomonas spp.) from wheat fields of the Upper Great Plains, USA as well as the different Fusarium species and chemotypes being used in this study, will be analysed in a microtiter assay using different carbon sources and concentrations as substrate. This will serve to explain varying antagonistic interactions between suppressive rhizobacteria and soilborne pathogens in cereals. Additionally, it is planned to study the impact of DON for successful wheat root and stem base infections by F. culmorum under field conditions. Experiments on DON as virulence factor for root infection by Fusarium species will be also conducted with barley. In experiments under controlled conditions it is planned to analyze whether the mycotoxin DON is translocated from the stem basis into barley kernels following stem base infections with toxigenic Fusarium species, which might be an additionally source of mycotoxin contamination of mature barley kernels.