Production of brassinolide-like substances by fungi.

根据水稻叶片倾斜试验，对1098株真菌细胞的甲醇提取物中的油菜素内酯进行了活性筛选。32株菌株表现出高达10 ng/g湿细胞级活性。它们分别属于克宁汉姆氏菌、青霉菌、木霉菌、曲霉菌、枝孢霉菌等。油菜素内酯活性的生产力在真菌属中存在偏见，但在该属中普遍存在。即使添加了不同的甾体化合物，单位细胞的活性也不依赖于培养基组分。在硅胶柱层析中，甲醇提取物的活性主要分离为两个组分，一个比油菜素内酯疏水性强，另一个亲水性明显。前者为主要成分，占总有效部位的60%。用甲醇、乙酸乙酯和丙酮连续提取、Almina和硅胶柱层析、制备型高效液相色谱分离，从7 kg湿细胞中分离纯化得到4.5g的疏水性物质。该物质经TLC和GC/MS鉴定为单油酯。来自植物的商业单油酸酯产品也显示出油菜素内酯的活性。油酸的活性仅为油菜素内酯的万分之一，其活性为10微克/毫升，油酸的活性仅为油酸的十分之一。讨论了油酸及其衍生物在植物体内的生理作用。

Brassinolide activity was screened in methanol extracts of the cells of 1098 fungal strains, accordind to rice lamina inclination test. Thirty two strains were found to show as high as 10 ng/g wet cell-level activity. They belong to Cunninghamella, Penicillium, Trichoderma, Aspergillus, Cladosporium and others. Productivity of brassinolide activity was present prejudically among fungal genera, but commonly in the genus. The activity per cells did not depend on the composition of culture media even when various steroidal compounds were added. The activity in methanol extracts was separated mainly into two fractions in silica gel column chromatography; one which was more hydrophobic than brassinolide and the other which was markedly hydrophilic. The former one was the major substance, weighing 60% of the total active fractions. Four and a half g of the hydrophobic substance was purified from 7 kg wet cells of Cunninghamella blakesleeana by successive extraction with methanol, ethyl acetate, and acetone, column chromatographys on almina and silica gel, and preparative HPLC. The substance was identified by TLC and GC/MS as monoolein. Commercial products of monoolein from plants also showed brassinolide activity. Activity of monoolein was one twenty thousandth of brassinolide and was detected at a level of 10 <micro> g/ml. Oleic acid was tenth as active as monoolein. Physiological role of oleic acid and its derivatives in plant was discussed.