Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, China.
Agronomy College, Sichuan Agricultural University, Chengdu, Sichuan 611130, China.
Sci Rep. 2017 Apr 7;7:46129. doi: 10.1038/srep46129.
Fusarium graminearum is the major causal agent of fusarium head blight in wheat, a serious disease worldwide. Linoleic acid isomerase (LAI) catalyses the transformation of linoleic acid (LA) to conjugated linoleic acid (CLA), which is beneficial for human health. We characterised a cis-12 LAI gene of F. graminearum (FGSG_02668; FgLAI12), which was downregulated by salicylic acid (SA), a plant defence hormone. Disruption of FgLAI12 in F. graminearum resulted in decreased accumulation of cis-9,trans-11 CLA, enhanced sensitivity to SA, and increased accumulation of LA and SA in wheat spikes during infection. In addition, mycelial growth, accumulation of deoxynivalenol, and pathogenicity in wheat spikes were reduced. Re-introduction of a functional FgLAI12 gene into ΔFgLAI12 recovered the wild-type phenotype. Fluorescent microscopic analysis showed that FgLAI12 protein was usually expressed in the septa zone of conidia and the vacuole of hyphae, but was expressed in the cell membrane of hyphae in response to exogenous LA, which may be an element of LA metabolism during infection by F. graminearum. The cis-12 LAI enzyme encoded by FgLAI12 is critical for fungal response to SA, mycelial growth and virulence in wheat. The gene FgLAI12 is potentially valuable for biotechnological synthesis of cis-9,trans-11 CLA.
镰刀菌禾谷孢（Fusarium graminearum）是小麦赤霉病的主要致病菌，这是一种全球性的严重疾病。亚油酸异构酶（LAI）催化亚油酸（LA）向共轭亚油酸（CLA）的转化，CLA 对人体健康有益。我们对 F. graminearum 的顺式-12 LAI 基因（FGSG_02668；FgLAI12）进行了表征，该基因受植物防御激素水杨酸（SA）下调。F. graminearum 中 FgLAI12 的缺失导致顺式-9,trans-11 CLA 的积累减少，对 SA 的敏感性增强，以及感染期间小麦穗中 LA 和 SA 的积累增加。此外，菌丝生长、脱氧雪腐镰刀菌烯醇的积累和在小麦穗中的致病性降低。将功能正常的 FgLAI12 基因重新导入 ΔFgLAI12 中恢复了野生型表型。荧光显微镜分析表明，FgLAI12 蛋白通常在分生孢子的隔膜区和菌丝的液泡中表达，但在响应外源性 LA 时在菌丝的细胞膜中表达，这可能是 F. graminearum 感染期间 LA 代谢的一个要素。FgLAI12 编码的顺式-12 LAI 酶对真菌对 SA 的反应、菌丝生长和在小麦中的毒力至关重要。该基因 FgLAI12 可能对生物技术合成顺式-9,trans-11 CLA 具有价值。
