Pedras M Soledade C, Yu Yang
Department of Chemistry, University of Saskatchewan, Saskatoon, Canada.
Phytochemistry. 2008 Dec;69(17):2966-71. doi: 10.1016/j.phytochem.2008.09.015. Epub 2008 Oct 30.
During a search for elicitors and phytotoxins produced by virulent isolates of the phytopathogenic fungus Leptosphaeria maculans (Desm.) Ces. et de Not. [asexual stage Phoma lingam (Tode ex Fr.) Desm.], the selective phytotoxin maculansin A was isolated and its structure determined by analysis of spectroscopic data and chemical degradation. Maculansin A, a unique derivative of mannitol containing the unusual chromophore 2-isocyano-3-methyl-2-butenoyl, was isolated from potato dextrose cultures of L. maculans virulent on canola (Brassica napus L. cv. Westar). Surprisingly, maculansin A was more toxic to resistant plants (B. juncea L. cv. Cutlass, brown mustard) than to susceptible plants (canola). Maculansin A, however, did not elicit the production of phytoalexins either in resistant or susceptible plants. In addition, other maculansin type structures and the metabolite 2,4-dihydroxy-3,6-dimethylbenzaldehyde were isolated and the latter was found to be a strong inhibitor of root growth of both brown mustard and canola. Considering that L. maculans seems to be expanding its host range to infect brown mustard as well, maculansins could assist in chemotaxonomic studies to group the diverse isolates.
在寻找由植物致病真菌大茎点菌（Leptosphaeria maculans (Desm.) Ces. et de Not.）[无性阶段为十字花科茎点霉（Phoma lingam (Tode ex Fr.) Desm.）]的强毒株产生的激发子和植物毒素的过程中，分离出了选择性植物毒素大茎点菌素A，并通过光谱数据分析和化学降解确定了其结构。大茎点菌素A是甘露醇的一种独特衍生物，含有不寻常的发色团2-异氰基-3-甲基-2-丁烯酰基，它是从对油菜（Brassica napus L. cv. Westar）具有毒性的大茎点菌的马铃薯葡萄糖培养基中分离得到的。令人惊讶的是，大茎点菌素A对抗性植物（芥菜（B. juncea L. cv. Cutlass），褐芥）的毒性比对敏感植物（油菜）的毒性更大。然而，大茎点菌素A在抗性或敏感植物中均未引发植保素的产生。此外，还分离出了其他大茎点菌素类型的结构以及代谢产物2,4-二羟基-3,6-二甲基苯甲醛，并且发现后者是褐芥和油菜根系生长的强抑制剂。鉴于大茎点菌似乎正在扩大其寄主范围以感染褐芥，大茎点菌素可有助于对不同菌株进行化学分类学研究。
