The rice Raf-like MAPKKK OsILA1 confers broad-spectrum resistance to bacterial blight by suppressing the OsMAPKK4–OsMAPK6 cascade

• 作者: Jie Chen Lihan Wang Zeyu Yang Hongbo Liu Chuanliang Chu Zhenzhen Zhang Qinglu Zhang Xianghua Li Jinghua Xiao Shiping Wang Meng Yuan
• 来源期刊: 植物学报（英文版）
• 年，卷（期）: 2021,（10）
• 所属期刊栏目: Plant-biotic Interactions
• 页码范围: 1815-1832
• 页数: 18页
• 语种: 英文

摘要

Mitogen-activated protein kinase kinase kinase (MAPKKK) are the first components of MAPK cascades, which play pivotal roles in signaling during plant development and physiological processes. The genome of rice encodes 75 MAPKKKs, of which 43 are Raf-like MAPKKKs. The functions and action modes of most of the Raf-like MAPKKKs, whether they function as bona fide MAPKKKs and which are their downstream MAPKKs, are largely unknown. Here, we identified the osmapkkk43 mutant, which conferred broad-spectrum resistance to Xanthomonas oryzae pv. oryzae (Xoo), the destructive bacterial pathogen of rice. Oryza sativa (Os)MAPKKK43 encoding a Raf-like MAPKKK was previously known as Increased Leaf Angle 1 (OsILA1). Genetic analysis indicated that OsILA1 functioned as a negative regulator and acted upstream of the OsMAPKK4–OsMAPK6 cascade in rice–Xoo interactions. Unlike classical MAPKKKs, OsILA1 mainly phosphorylated the threonine 34 site at the N-terminal domain of Os-MAPKK4, which possibly influenced the stability of OsMAPKK4. The N-terminal domain of OsILA1 is required for its homodimer formation and its full phosphorylation capacity. Taken together, our findings reveal that OsILA1 acts as a negative regulator of the OsMAPKK4–OsMAPK6 cascade and is involved in rice–Xoo interactions.