中文摘要：

DHN黑色素是许多植物病原真菌的致病相关因子，为明确黑色素在玉米大斑病菌致病过程中的作用，采用三环唑和紫外线复合诱变的方法获得了黑色素缺失的6个突变菌株，对突变菌株的生长量、产孢量、HT-毒素活性、致病力进行测定。结果显示，突变菌株产毒能力变化不大，但生长量下降，产孢量和致病力显著下降或完全丧失，野生型菌株的产孢量和侵染频率分别是突变菌株的30～50倍和5倍。突变菌株与黑色素共培养后，菌株M01-23a和M01-23b恢复了致病力，但病斑面积和侵染频率较小。玉米大斑病菌黑色素与致病力具有一定的相关性。

英文摘要：

DHN melanin is considered as one of the important virulence factors for certain plant pathogenic fungi. The objective of this study was to examine the role of melanin of Setosphaeria turcica in the mechanism of pathogenesis. Six melanin-deficient mutants were obtained by UV radiation and tricyclazole mutating. The tests on the mycelial growth, the number of conidiophores, the activity of HT-toxin and pathogenesis were conducted, comparing the mutant isolates with wild type ones. The mycelial growth, the number of conidiophores and pathogenesis reduced greatly in mutant isolates, but the activity of HT- toxin didn＇t change obviously. Especially, the number of conidiophores and infections efficiency of wide type isolate is 30 -50 fold and 5 fold compared with mutants. After grown on PDA containing melanin, mutant isolates M01-23a and M01-23b resumed a little pathogenesis. The experimental results suggested that there was relativity between melanin and pathogenesis.