Leucine metabolism regulates TRI6 expression and affects deoxynivalenol production and virulence in Fusarium graminearum
Leucine metabolism regulates TRI6 expression and affects deoxynivalenol production and virulence in Fusarium graminearum
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DOI：
10.1111/mmi.13155
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发表时间：
2015-09
影响因子：
3.6
通讯作者：
R. Subramaniam;Swara Narayanan;S. Walkowiak;Li Wang;Manish K Joshi;Hélène Rocheleau;T. Ouellet;L. Harris
中科院分区：
文献类型：
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作者：
R. Subramaniam;Swara Narayanan;S. Walkowiak;Li Wang;Manish K Joshi;Hélène Rocheleau;T. Ouellet;L. Harris
TRI 6是禾谷镰刀菌（Fusarium graminearum）中的二孢霉烯基因簇和二孢霉烯真菌毒素[脱氧雪腐镰刀菌烯醇（DON）]和乙酰化形式（如15-乙酰基-DON）的产生的正调控因子。作为一种全局转录调节因子，TRI 6的表达受氮限制条件、氮源和碳源、pH和光照的调节。然而，这些不同的环境因素影响TRI 6表达的机制仍有待研究。在我们努力了解营养素如何影响TRI 6调控的过程中，用野生型F. graminearum和Δ tri 6突变株，在营养丰富的条件下生长。分析表明，TRI 6负调控支链氨基酸（BCAA）代谢途径的基因。用MCC的缺失突变体（编码甲基巴豆酰-CoA-羧化酶，亮氨酸代谢的关键酶之一）进行的饲养研究表明，添加亮氨酸特异性下调TRI 6表达并减少15-ADON积累。TRI 6在Δmcc突变株中的组成型表达恢复了15-ADON的生产。对小麦的玻璃纸破裂测定和致病性实验的组合表明，破坏亮氨酸代谢途径显著减少疾病。这些发现表明，一个复杂的相互作用之间的主要代谢途径与真菌毒素的生物合成和毒力的全球调节因子。禾谷早熟禾
TRI6 is a positive regulator of the trichothecene gene cluster and the production of trichothecene mycotoxins [deoxynivalenol (DON)] and acetylated forms such as 15‐Acetyl‐DON) in the cereal pathogen Fusarium graminearum. As a global transcriptional regulator, TRI6 expression is modulated by nitrogen‐limiting conditions, sources of nitrogen and carbon, pH and light. However, the mechanism by which these diverse environmental factors affect TRI6 expression remains underexplored. In our effort to understand how nutrients affect TRI6 regulation, comparative digital expression profiling was performed with a wild‐type F. graminearum and a Δtri6 mutant strain, grown in nutrient‐rich conditions. Analysis showed that TRI6 negatively regulates genes of the branched‐chain amino acid (BCAA) metabolic pathway. Feeding studies with deletion mutants of MCC, encoding methylcrotonyl‐CoA‐carboxylase, one of the key enzymes of leucine metabolism, showed that addition of leucine specifically down‐regulated TRI6 expression and reduced 15‐ADON accumulation. Constitutive expression of TRI6 in the Δmcc mutant strain restored 15‐ADON production. A combination of cellophane breach assays and pathogenicity experiments on wheat demonstrated that disrupting the leucine metabolic pathway significantly reduced disease. These findings suggest a complex interaction between one of the primary metabolic pathways with a global regulator of mycotoxin biosynthesis and virulence in F. graminearum.