Evidence from mycelial studies for differences in the sterol biosynthetic pathway of Rhizoctonia solani and Phytophthora cinnamomi.
Evidence from mycelial studies for differences in the sterol biosynthetic pathway of Rhizoctonia solani and Phytophthora cinnamomi.
复制标题
来自菌丝研究的证据表明立枯丝核菌和肉桂疫霉的甾醇生物合成途径存在差异。
作者：
S. Wood;D. Gottlieb
Phytophthora cinnamomi是Pythiacease的成员，不合成甾醇。在无固醇培养基中生长后，从该真菌的干燥菌丝体中分离出少量角鲨烯，但没有角鲨烯环氧化物或固醇。在相同条件下生长的一种甾醇合成真菌立枯丝核菌的干燥菌丝体中含有少量角鲨烯和角鲨烯环氧化物以及大量麦角甾醇。当这两种微生物在[14 C]乙酸盐存在下生长时，从P. cinnamomi菌丝体中仅回收到标记的香叶醇、法呢醇和角鲨烯，而从R.茄属菌丝体当在[2（-14）C]甲羟戊酸存在下孵育微生物时，获得了类似的结果;在这种情况下，在R.茄属菌丝体两种微生物在未标记的角鲨烯、角鲨烯环氧化物或羊毛甾醇存在下孵育时，都将这些化合物掺入其菌丝体中; Solani菌丝体能够沿着甾醇途径进一步沿着将这些底物转化为产物。角鲨烯可能是樟芝甾醇生物合成途径的末端化合物。
Phytophthora cinnamomi, a member of the Pythiacease, does not synthesize sterols. Small amounts of squalene, but no squalene epoxide or sterol, were isolated from the dried mycelium of this fungus after growth in sterol-free medium. The dried mycelium of Rhizoctonia solani, a sterol-synthesizing fungus grown under the same conditions, contained small amounts of squalene and squalene epoxide and large amounts of ergosterol. When the two organisms were grown in the presence of [14C]acetate, only labelled geraniol, farnesol and squalene were recovered from the P. cinnamomi mycelium, whereas labelled geraniol, farnesol, squalene, squalene epoxide and ergosterol were recovered from the R. solani mycelium. Similar results were obtained when the organisms were incubated in the presence of [2(-14)C]mevalonate; in this case, labelled lanosterol was also detected in the R. solani mycelium. Both organisms, when incubated in the presence of unlabelled squalene, squalene epoxide or lanosterol, incorporated these compounds into their mycelia; however, only the R. solani mycelium was able to convert these substrates into products further along the sterol pathway. It appears that squalene is the terminal compound in the sterol biosynthetic pathway of P. cinnamomi.