Zhang Ruina, Pei Mengtian, Lin Shiyi, Chen Jing, Biregeya Jules, Song Linlin, Peng Changlin, Jiang Pengcheng, Lu Guo-Dong
State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops and Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
Rice (N Y). 2024 Nov 4;17(1):68. doi: 10.1186/s12284-024-00747-3.
Phosphatidylinositol signaling system plays a crucial role in plant physiology and development, phosphatidylinositol phosphate kinases (PIPKs) are one of the essential enzymes responsible for catalyzing the synthesis of phosphatidylinositol bisphosphate (PIP2) within this signaling pathway. However, its mechanism of signal transduction remains poorly exploited in plants. OsMBL1, a jacalin-related mannose-binding lectin in rice, plays a crucial role in plant defense mechanisms, acting as a key component of the pattern-triggered immunity (PTI) pathway. Here, a rice phosphatidylinositol-phosphate kinase FAB (OsPIPK-FAB), a member of the rice PIPKs family, as an interacting protein of OsMBL1 through yeast-two-hybrid (Y2H) screening assay. And this interaction was confirmed by using co-immunoprecipitation (Co-IP) and pull-down assay techniques. Furthermore, we demonstrated that the deletion of OsPIPK-FAB gene in plant enhanced resistance against rice blast while overexpression of OsPIPK-FAB increases sensitivity to the fungal infection. Additionally, through determination and measurement of the plant inositol 1,4,5-trisphosphate (IP3) contents and the plant phosphatidylinositol 4-phosphate 5-kinase (PIP5K) activity, we revealed that OsMBL1 inhibits the PIP5K kinase activity of OsPIPK-FAB as well as the plant IP3 contents in rice. Conclusively, these findings indicated that OsPIPK-FAB serves as a novel and critical component that is negatively involved in PTI activation and was inhibited by OsMBL1.
磷脂酰肌醇信号系统在植物生理和发育过程中发挥着关键作用，磷脂酰肌醇磷酸激酶（PIPKs）是该信号通路中负责催化磷脂酰肌醇二磷酸（PIP2）合成的关键酶之一。然而，其信号转导机制在植物中仍未得到充分研究。水稻中的一种与jacalin相关的甘露糖结合凝集素OsMBL1在植物防御机制中起着关键作用，是模式触发免疫（PTI）途径的关键组成部分。在此，通过酵母双杂交（Y2H）筛选试验，发现水稻磷脂酰肌醇磷酸激酶FAB（OsPIPK-FAB）作为水稻PIPKs家族的一员，是OsMBL1的相互作用蛋白。并且通过免疫共沉淀（Co-IP）和下拉试验技术证实了这种相互作用。此外，我们证明了植物中OsPIPK-FAB基因的缺失增强了对稻瘟病的抗性，而OsPIPK-FAB的过表达增加了对真菌感染的敏感性。另外，通过测定和测量植物肌醇1,4,5-三磷酸（IP3）含量和植物磷脂酰肌醇4-磷酸5-激酶（PIP5K）活性，我们发现OsMBL1抑制了OsPIPK-FAB的PIP5K激酶活性以及水稻中的植物IP3含量。总之，这些发现表明OsPIPK-FAB是一个新的关键组分，在PTI激活中起负作用，并受到OsMBL1的抑制。
