在水稻对白叶枯病的防御中，两种VQ蛋白是OsMPKK6-OsMPK4级联反应的底物。

Two VQ Proteins are Substrates of the OsMPKK6-OsMPK4 Cascade in Rice Defense Against Bacterial Blight.

作者信息

Li Na, Yang Zeyu, Li Juan, Xie Wenya, Qin Xiaofeng, Kang Yuanrong, Zhang Qinglu, Li Xianghua, Xiao Jinghua, Ma Haigang, Wang Shiping

机构信息

National Key Laboratory of Crop Genetic Improvement, National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan, 430070, China.

出版信息

Rice (N Y). 2021 Apr 28;14(1):39. doi: 10.1186/s12284-021-00483-y.

BACKGROUND

The plant-specific valine-glutamine (VQ) protein family with the conserved motif FxxxVQxLTG reportedly functions with the mitogen-activated protein kinase (MAPK) in plant immunity. However, the roles of VQ proteins in MAPK-mediated resistance to disease in rice remain largely unknown.

RESULTS

In this study, two rice VQ proteins OsVQ14 and OsVQ32 were newly identified to function as the signaling components of a MAPK cascade, OsMPKK6-OsMPK4, to regulate rice resistance to Xanthomonas oryzae pv. oryzae (Xoo). Both OsVQ14 and OsVQ32 positively regulated rice resistance to Xoo. In vitro and in vivo studies revealed that OsVQ14 and OsVQ32 physically interacted with and were phosphorylated by OsMPK4. OsMPK4 was highly phosphorylated in transgenic plants overexpressing OsMPKK6, which showed enhanced resistance to Xoo. Meanwhile, phosphorylated OsVQ14 and OsVQ32 were also markedly accumulated in OsMPKK6-overexpressing transgenic plants.

CONCLUSIONS

We discovered that OsVQ14 and OsVQ32 functioned as substrates of the OsMPKK6-OsMPK4 cascade to enhance rice resistance to Xoo, thereby defining a more complete signal transduction pathway for induced defenses.

背景

据报道，具有保守基序FxxxVQxLTG的植物特异性缬氨酸 - 谷氨酰胺（VQ）蛋白家族在植物免疫中与丝裂原活化蛋白激酶（MAPK）共同发挥作用。然而，VQ蛋白在水稻中MAPK介导的抗病性中的作用仍 largely未知。

结果

在本研究中，新鉴定出两种水稻VQ蛋白OsVQ14和OsVQ32作为MAPK级联反应OsMPKK6 - OsMPK4的信号成分，以调节水稻对水稻白叶枯病菌（Xanthomonas oryzae pv. oryzae，Xoo）的抗性。OsVQ14和OsVQ32均正向调节水稻对Xoo的抗性。体外和体内研究表明，OsVQ14和OsVQ32与OsMPK4发生物理相互作用并被其磷酸化。在过表达OsMPKK6的转基因植物中，OsMPK4高度磷酸化，对Xoo表现出增强的抗性。同时，磷酸化的OsVQ14和OsVQ32在过表达OsMPKK6的转基因植物中也显著积累。