Tsitsigiannis Dimitrios I, Keller Nancy P
Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706, USA.
Mol Microbiol. 2006 Feb;59(3):882-92. doi: 10.1111/j.1365-2958.2005.05000.x.
Secreted, hormone-like lipogenic molecules, called oxylipins, mediate the balance of asexual to sexual spore ratio in Aspergillus nidulans. Oxylipin production in this fungus is dependent on developmental regulation of three conserved fatty acid oxygenases, PpoA, PpoB and PpoC. Here, we show that in addition to altering spore ratios, loss of ppo genes affect natural product biosynthesis and seed colonization. DeltappoA;DeltappoC and DeltappoA;DeltappoB;DeltappoC mutants were unable to produce the mycotoxin sterigmatocystin (ST) in vitro or in planta but in contrast overproduced the antibiotic penicillin (PN). These findings were correlated with decreased expression of genes involved in ST biosynthesis and increased expression of a PN biosynthetic gene, thus suggesting that oxylipin species regulate secondary metabolites at the transcriptional level. Additionally, the DeltappoA;DeltappoC and the DeltappoA;DeltappoB;DeltappoC mutants were defective in colonization of peanut seeds as reflected by a decrease in conidiation and production of the seed degradative enzyme lipase. These results indicate that oxylipin production is important for host colonization and mycotoxin production and may provide a promising target for future control strategies.
被称为氧脂素的分泌型、激素样生脂分子介导构巢曲霉无性孢子与有性孢子比例的平衡。该真菌中氧脂素的产生依赖于三种保守脂肪酸加氧酶PpoA、PpoB和PpoC的发育调控。在此，我们表明，除了改变孢子比例外，ppo基因的缺失还会影响天然产物的生物合成和种子定殖。DeltappoA;DeltappoC和DeltappoA;DeltappoB;DeltappoC突变体在体外或植物体内均无法产生霉菌毒素柄曲霉素（ST），但相比之下，青霉素（PN）的产量却过高。这些发现与ST生物合成相关基因表达的降低以及PN生物合成基因表达的增加相关，从而表明氧脂素种类在转录水平上调节次生代谢产物。此外，DeltappoA;DeltappoC和DeltappoA;DeltappoB;DeltappoC突变体在花生种子定殖方面存在缺陷，这表现为分生孢子形成减少以及种子降解酶脂肪酶的产生减少。这些结果表明，氧脂素的产生对于宿主定殖和霉菌毒素的产生很重要，并且可能为未来的控制策略提供一个有前景的靶点。
