中文摘要：

【目的】对玉米大斑病菌胞外黑色素的种类进行确定，探索影响玉米大斑病菌野生型菌株胞外黑色素产量的因素。【方法】利用酸碱沉淀法提取玉米大斑病菌01-23（野生型）菌株和1，3，8-三羟基萘还原酶（3HNR）基因缺失突变菌株ASt3har-3的胞外黑色素，采用红外光谱分析确定黑色素的种类。通过在培养基中添加不同的物质，确定影响胞外黑色素产量的因素。【结果】玉米大斑病菌胞外黑色素不同于DHN黑色素，2种黑色素的理化性质相似，溶解于热碱溶液，且与FeCl3反应产生沉淀。在振荡培养条件下，加入酪氨酸和三环唑分别使胞外黑色素的产量提高了2倍和1．5倍，而Cu2＋浓度低于0．5μmol·L-1利于胞外黑色素的合成，反之则表现抑制作用；pH值为6时较利于对胞外黑色素分泌。【结论】玉米大斑病菌胞外黑色素为DOPA黑色素类型，酪氨酸和三环唑对胞外黑色素的产生具有明显促进作用。

英文摘要：

[Objective] The objective of this study is to determine the type ofextracellular melanin from Setosphaeria turcica and explore the influencing factors of its production to lay a foundation for further clarification of the relationship between melanin and pathogenicity. [Method] Acid precipitation method was used to extract the extracellular melanin of 01-23 and ASt3hnr-3 strain. The type of melanin was preliminarily identified with infrared spectroscopy. Media containing tyrosine, tricyclazole, Cu2＋.and different pH values were used to determine the influences of these factors on the production of extracellular melanin. [ Result ] The infrared spectroscopy of extracellular melanin in S. turcica was different from the DHN melanin, while the physical and chemical properties of the samples from both strains were similar. It could dissolve in hot alkaline solution and produce precipitation when it was reacted with FeCl3. Under the shaking culture, the contents of extracellular melanin in the culture filtrates respectively containing tyrosine and tricyclazole were about 2 and 1.5 times more than that of the mock, while it could also be slightly enhanced by Cu2＋ with the concentration lower than 0.5μmol.L-1 or at pH6.0. [Conclusion] The extracellular melanin from S. turcica was proved to be similar with DOPA melanin. Tyrosine and tricyclazole obviously promoted the production of extracellular melanin.