肉桂枝枯病菌毒素的研究

本文是对肉桂枝枯病病原菌毒素研究的首例报道。生物活性测定显示，病菌知液体培养基中可产生导致内桂嫩梢萎蔫和叶盘褐变坏死的致病毒素。改良Fries液体培养基振荡培养和PD液体培养基青止培养为较好的产毒培养方式。病原菌毒素为非寄主专化性毒素，除肉桂外，还对香樟、马尾松、薇苷菊、卤地菊和番茄等植物具有致萎活性，毒素为弱酸性（pH5.4），对冷、热稳定性强，极性较大，易深于水、乙醇、丙酮、正丁醇＋丙桐及乙酸乙酯，部分溶于氯仿，基本不溶于乙醚。研究表明毒素为非蛋白质、多糖及核酸类大分子物质。含毒滤液可能含有糖醛类物质，其致毒活性经乙醇和丙酮纯化后有所增强，经HPLC分离出的组分I可能为毒性成份。肉桂叶盘经毒素处理后，其相对电导率较对照大幅度增加，感病的本地桂比抗病的大叶青化桂增加更为明显。

Studies on Toxin Produced by Botryodiplodia theobromae

A toxic substance produced by Botryodiplodia theobromae in liquid culture, its physical and chemical properties and effects on Cinnamomun cassia were studied. Bioassay indicated that the metabolites of B. theobromae caused wilt on C. cassia new sprouts and necrosis on leaf discs. The toxin is non host specific and toxic to plants other than C. cassia such as Cinnamomum camphora, Pinus massorian, Wedelia prostuata, Lycopersicon esculentum and Mikania micrantha. The toxin was weakly acidic, heat and cold stable, dissolved easily in water, ethanol, acetone, n butanol acetone, moderately dissolved in acetic ester, slightly in chloroform and not in ether. The toxin did not belong to proteins, nucleic acids and polysaccharides. However, the toxic filtrate contained aldose. The toxicity was increased after ethanol and acetone treatment. High performance liquid chromatography from ethyl acetate extract of the toxin revealed four major fractions. After treated with the toxin, the relative electrical conductivity of C. cassia leaf discs increased dramatically in comparison to that of the control. When exposed to the same level of toxin concentration, the electrical conductivity of susceptible C. cassia is higher than that of resistant C. cassia var. macrophyllumone.