Department of Biological Sciences, University of North Texas, Denton, Texas, USA.
BioDiscovery Institute, University of North Texas, Denton, Texas, USA.
Mol Plant Pathol. 2022 Aug;23(8):1141-1153. doi: 10.1111/mpp.13216. Epub 2022 Apr 9.
Fusarium graminearum (Fg) is an important fungal pathogen of small grain cereals that can also infect Arabidopsis thaliana. In Arabidopsis, jasmonic acid (JA) signalling involving JASMONATE RESISTANT 1 (JAR1), which synthesizes JA-isoleucine, a signalling form of JA, promotes susceptibility to Fg. Here we show that Arabidopsis MYZUS PERSICAE-INDUCED LIPASE 1 (MPL1), via its influence on limiting JA accumulation, restricts Fg infection. MPL1 expression was up-regulated in response to Fg infection, and MPL1-OE plants, which overexpress MPL1, exhibited enhanced resistance against Fg. In comparison, disease severity was higher on the mpl1 mutant than the wild type. JA content was lower in MPL1-OE and higher in mpl1 than in the wild type, indicating that MPL1 limits JA accumulation. Pharmacological experiments confirmed the importance of MPL1-determined restriction of JA accumulation on curtailment of Fg infection. Methyl-JA application attenuated the MPL1-OE-conferred resistance, while the JA biosynthesis inhibitor ibuprofen enhanced resistance in mpl1. Also, the JA biosynthesis-defective opr3 mutant was epistatic to mpl1, resulting in enhanced resistance in mpl1 opr3 plants. In comparison, JAR1 was not essential for the mpl1-conferred susceptibility to Fg. Considering that methyl-JA promotes Fg growth in culture, we suggest that in part MPL1 curtails disease by limiting the availability of a plant-derived Fg growth-promoting factor.
镰刀菌禾谷种（Fg）是一种重要的小谷物真菌病原体，也可以感染拟南芥。在拟南芥中，茉莉酸（JA）信号转导涉及茉莉酸抗性 1（JAR1），它合成 JA-异亮氨酸，JA 的信号形式，促进对 Fg 的易感性。在这里，我们表明，拟南芥桃蚜诱导的脂肪酶 1（MPL1）通过其对限制 JA 积累的影响，限制 Fg 感染。MPL1 的表达响应 Fg 感染而上调，并且过表达 MPL1 的 MPL1-OE 植物对 Fg 表现出增强的抗性。相比之下，mpl1 突变体上的疾病严重程度高于野生型。MPL1-OE 和 mpl1 中的 JA 含量低于野生型，表明 MPL1 限制 JA 积累。药理学实验证实了 MPL1 决定的 JA 积累限制对减少 Fg 感染的重要性。甲基-JA 的应用减弱了 MPL1-OE 赋予的抗性，而 JA 生物合成抑制剂布洛芬增强了 mpl1 的抗性。此外，JA 生物合成缺陷型 opr3 突变体与 mpl1 上位性，导致 mpl1 opr3 植物的抗性增强。相比之下，JAR1 对 mpl1 赋予的对 Fg 的易感性不是必需的。考虑到甲基-JA 在培养中促进 Fg 的生长，我们认为 MPL1 部分通过限制植物来源的 Fg 生长促进因子的可用性来限制疾病。
