School of Botany, The University of Melbourne, Victoria 3010, Australia.
Fungal Genet Biol. 2013 Apr;53:50-8. doi: 10.1016/j.fgb.2013.01.008. Epub 2013 Feb 7.
Phomenoic acid, a long chain aliphatic carboxylic acid is a major metabolite produced by Leptosphaeria maculans, a fungal pathogen of Brassica napus (canola). This fungus has 15 predicted polyketide synthases (PKS) and seven of them have the appropriate domains for the biosynthesis of phomenoic acid. The most highly expressed PKS gene after 7 days growth in 10% V8 juice, PKS2, was silenced and the resultant mutant produced very low levels of phomenoic acid, indicating that this PKS is involved in phomenoic acid biosynthesis. This gene is part of a co-regulated cluster of genes. Reduced expression of an adjacent gene encoding the transcriptional regulator C6TF, led to reduced expression of genes for PKS2, P450, a cytochrome P450 monoxygenase, YogA, an alcohol dehydrogenase/quinone reductase, RTA1, a lipid transport exporter superfamily member and MFS, a Major Facilitator Superfamily transporter, as well as a marked reduction in phomenoic acid production. Phomenoic acid is toxic towards another canola pathogen Leptosphaeria biglobosa 'canadensis', but not towards L. maculans and only moderately toxic towards the wheat pathogen Stagonospora nodorum. This molecule is detected in infected stems and stubble of B. napus, but biosynthesis of it does not appear to be essential for pathogenicity of L. maculans. Phomenoic acid may play a role in allowing L. maculans to outcompete other fungi in its environmental niche.
非马酸，一种长链脂肪羧酸，是菜籽油真菌病原体菜黑粉菌产生的主要代谢产物。该真菌有 15 个预测的聚酮合酶（PKS），其中 7 个具有生物合成非马酸的适当结构域。在 10%V8 汁中生长 7 天后，表达量最高的 PKS 基因 PKS2 被沉默，其产生的非马酸水平非常低，表明该 PKS 参与非马酸的生物合成。该基因是一个共同调控基因簇的一部分。相邻基因编码转录调节因子 C6TF 的表达减少，导致 PKS2、P450（细胞色素 P450 单加氧酶）、YogA（醇脱氢酶/醌还原酶）、RTA1（脂质转运外排超家族成员）和 MFS（主要易化剂超家族转运蛋白）的基因表达减少，以及非马酸产量显著降低。非马酸对另一种油菜病原体菜黑粉菌“加拿大”具有毒性，但对菜黑粉菌和小麦病原体禾谷镰刀菌的毒性较弱。该分子在感染的油菜茎和茬中被检测到，但它的生物合成似乎不是菜黑粉菌致病性所必需的。非马酸可能在允许菜黑粉菌在其环境小生境中与其他真菌竞争中发挥作用。
