Rice RING protein OsBBI1 with E3 ligase activity confers broad-spectrum resistance against Magnaporthe oryzae by modifying the cell wall defence

• Published in: Cell research Vol. 21; no. 5; pp. 835 - 848
• Main Authors: Li, Wei, Zhong, Sihui, Li, Guojun, Li, Qun, Mao, Bizeng, Deng, Yiwen, Zhang, Huijuan, Zeng, Longjun, Song, Fengming, He, Zuhua
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.05.2011; Nature Publishing Group
• Subjects: 631/449/2169; 631/449/448/1365; 631/80/474/2073; 692/699/255/1672; Amino Acid Sequence; Biochemical analysis; Biomedical and Life Sciences; Cell Biology; Cell Wall - drug effects; Cell Wall - immunology; Cell Wall - microbiology; Cell Wall - ultrastructure; Disease resistance; Hydrogen Peroxide - metabolism; Immunity, Innate; Life Sciences; Magnaporthe - drug effects; Magnaporthe - physiology; Molecular Sequence Data; Mutation - genetics; Original; original-article; Oryza sativa; Phenols; Phenols - metabolism; Plant Diseases - immunology; Plant Diseases - microbiology; Plant Epidermis - cytology; Plant Epidermis - metabolism; Plant Epidermis - microbiology; Plant Epidermis - ultrastructure; Plant Proteins - chemistry; Plant Proteins - metabolism; Salicylic Acid - pharmacology; Sequence Alignment; Thiadiazoles - pharmacology; Transgenic plants; Ubiquitin-Protein Ligases - metabolism; 修改; 广谱抗性; 水稻基因; 泛素连接酶; 活性蛋白; 稻瘟病菌; 细胞壁; 转基因植物; E3 ligase activity; cell wall defence; disease resistance; rice; blast fungus
• ISSN: 1001-0602; 1748-7838
• DOI: 10.1038/cr.2011.4

Emerging evidence suggests that E3 ligases play critical roles in diverse biological processes, including innate immune responses in plants. However, the mechanism of the E3 ligase involvement in plant innate immunity is unclear. We report that a rice gene, OsBBI1, encoding a RING finger protein with E3 ligase activity, mediates broad-spectrum disease resistance. The expression of OsBBI1 was induced by rice blast fungus Magnaporthe oryzae, as well as chemical inducers, benzothiadiazole and salicylic acid. Biochemical analysis revealed that OsBBI1 protein possesses E3 ubiquitin ligase activity in vitro. Genetic analysis revealed that the loss of OsBBI1 function in a Tosl 7-insertion line increased susceptibility, while the overexpression of OsBBI1 in transgenic plants conferred enhanced resistance to multiple races of M. oryzae. This indicates that OsBBI1 modulates broad-spectrum resistance against the blast fungus. The OsBBIl-overexpressing plants showed higher levels of H202 accumulation in cells and higher levels of phenolic compounds and cross-linking of proteins in cell walls at infection sites by M. oryzae compared with wild-type （WT） plants. The cell walls were thicker in the OsBBIl-overexpressing plants and thinner in the mutant plants than in the WT plants. Our results suggest that OsBBI1 modulates broad-spectrum resistance to blast fungus by modifying cell wall defence responses. The functional characterization of OsBBI1 provides insight into the E3 ligase-mediated innate immunity, and a practical tool for constructing broad-spectrum resistance against the most destructive disease in rice.