OsPG1 Encodes a Polygalacturonase that Determines Cell Wall Architecture and Affects Resistance to Bacterial Blight Pathogen in Rice

Rice

Daibo Chen¹  Weixun Wu¹  Yongrun Cao¹  Shihua Cheng¹  Qunen Liu¹  Yuyu Chen¹  Ning Yu¹  Xinghua Wei¹  Liyong Cao¹  Yue Zhang¹  Shah Liaqat¹  Yingxin Zhang¹ 

[1] State Key Laboratory of Rice Biology, China National Rice Research Institute, 310006, Zhejiang, Hangzhou, China;Key Laboratory for Zhejiang Super Rice Research, China National Rice Research Institute, 310006, Zhejiang, Hangzhou, China;

关键词: Rice;    Leaf tip necrosis;    Polygalacturonase;    Bacterial blight;    Cell wall;   

DOI  :  10.1186/s12284-021-00478-9

来源: Springer

【 摘 要 】

BackgroundPlant cell walls are the main physical barrier encountered by pathogens colonizing plant tissues. Alteration of cell wall integrity (CWI) can activate specific defenses by impairing proteins involved in cell wall biosynthesis, degradation and remodeling, or cell wall damage due to biotic or abiotic stress. Polygalacturonase (PG) depolymerize pectin by hydrolysis, thereby altering pectin composition and structures and activating cell wall defense. Although many studies of CWI have been reported, the mechanism of how PGs regulate cell wall immune response is not well understood.ResultsNecrosis appeared in leaf tips at the tillering stage, finally resulting in 3–5 cm of dark brown necrotic tissue. ltn-212 showed obvious cell death and accumulation of H2O2 in leaf tips. The defense responses were activated in ltn-212 to resist bacterial blight pathogen of rice. Map based cloning revealed that a single base substitution (G-A) in the first intron caused incorrect splicing of OsPG1, resulting in a necrotic phenotype. OsPG1 is constitutively expressed in all organs, and the wild-type phenotype was restored in complementation individuals and knockout of wild-type lines resulted in necrosis as in ltn-212. Transmission electron microscopy showed that thicknesses of cell walls were significantly reduced and cell size and shape were significantly diminished in ltn-212.ConclusionThese results demonstrate that OsPG1 encodes a PG in response to the leaf tip necrosis phenotype of ltn-212. Loss-of-function mutation of ltn-212 destroyed CWI, resulting in spontaneous cell death and an auto-activated defense response including reactive oxygen species (ROS) burst and pathogenesis-related (PR) gene expression, as well as enhanced resistance to Xanthomonas oryzae pv. oryzae (Xoo). These findings promote our understanding of the CWI mediated defense response.

【 授权许可】

CC BY