Molecular determinants of host specificity of maize-, rice- and mango-pathogenic species of the genus Fusarium

由赤霉菌属复合种组成的镰刀菌在水稻、小麦和玉米等作物上引起严重病害。一类重要的植物病原菌是赤霉菌复合体(Gibberella fujikuroi Species Complex，GFC)，该复合体由与特定寄主相关的镰刀菌物种组成，其中轮纹镰刀菌和增殖镰刀菌尤其与玉米有关，它们能引起严重的穗、根和茎腐烂病。GFC的另外两个近缘种芒果镰刀菌(F.mangiferae)和藤冈镰刀菌(F.Fujikuroi)分别是芒果和水稻上的病原菌，它们与黄萎病病菌的序列同源性约为90%。所有这些物种都产生广泛的次生代谢产物，如植物激素(赤霉素、生长素和细胞分裂素)，以及有害的真菌毒素，如伏马菌素、镰刀菌素C或镰刀菌酸。然而，这些真菌毒素的光谱可能在密切相关的物种之间有所不同，这表明次生代谢物可能是宿主特异性的决定因素。在这个项目中，我们将研究次生代谢物(如植物激素和某些真菌毒素)和其他一些物种特异性因子(如物种特异性转录因子)对宿主特异性的潜在影响。本课题组最近测序的芒果镰刀菌和Fujikuroi镰刀菌的基因组，以及计划中的增殖镰刀菌基因组测序，将有助于通过适当的代谢途径的遗传操作来识别这些决定因素(S)。

Fusarium species of the Gibberella fujikuroi species complex cause serious diseases on different crops such as rice, wheat and maize. An important group of plant pathogens is the Gibberella fujikuroi species complex (GFC) of closely related Fusarium species which are associated with specific hosts; F. verticillioides and F. proliferatum are particularly associated with maize where they can cause serious ear-, root-, and stalk rot diseases. Two other closely related species of the GFC, F. mangiferae and F. fujikuroi, which share about 90% sequence identity with F. verticillioides, are pathogens on mango and rice, respectively. All of these species produce a broad spectrum of secondary metabolites such as phytohormones (gibberellins, auxins, and cytokinins), and harmful mycotoxins, such as fumonisin, fusarin C, or fusaric acid in large quantities. However, the spectrum of those mycotoxins might differ between closely related species suggesting that secondary metabolites might be determinants for host specificity. In this project, we will study the potential impact of secondary metabolites (i.e. phytohormones and certain mycotoxins) and some other species-specific factors (e.g. species-specific transcription factors) on host specificity. The recently sequenced genomes of F. mangiferae and F. fujikuroi by our groups and the planned sequencing of F. proliferatum will help to identify such determinants by genetic manipulation of the appropriate metabolic pathway(s).