부산대학교 도서관

SUMMARY: The plant cell boundary generally comprises constituents of the primary and secondary cell wall (CW) that are deposited sequentially during development. Although it is known that the CW acts as a barrier against phytopathogens and undergoes modifications to limit their invasion, the extent, sequence, and requirements of the pathogen‐induced modifications of the CW components are still largely unknown, especially at the level of the polysaccharide fraction. To address this significant knowledge gap, we adopted the compatible Pseudomonas syringae–Arabidopsis thaliana system. We found that, despite systemic signaling actuation, Pseudomonas infection leads only to local CW modifications. Furthermore, by utilizing a combination of CW and immune signaling‐deficient mutants infected with virulent or non‐virulent bacteria, we demonstrated that the pathogen‐induced changes in CW polysaccharides depend on the combination of pathogen virulence and the host's ability to mount an immune response. This results in a pathogen‐driven accumulation of CW hexoses, such as galactose, and an immune signaling‐dependent increase in CW pentoses, mainly arabinose, and xylose. Our analyses of CW changes during disease progression also revealed a distinct spatiotemporal pattern of arabinogalactan protein (AGP) deposition and significant modifications of rhamnogalacturonan sidechains. Furthermore, genetic analyses demonstrated a critical role of AGPs, specifically of the Arabinoxylan Pectin Arabinogalactan Protein1, in limiting pathogen growth. Collectively, our results provide evidence for the actuation of significant remodeling of CW polysaccharides in a compatible host‐pathogen interaction, and, by identifying AGPs as critical elements of the CW in plant defense, they pinpoint opportunities to improve plants against diverse pathogens. Significance Statement: Although potentiating resilience is foundational to crop improvement, and despite the notion that cell wall (CW) protects against pathogens, the extent of pathogen‐induced CW changes and the CW composition requirements for a successful defense are largely unknown. By investigating the bacteria‐induced impact on the Arabidopsis CW, we found changes exclusively in infected leaves with the remodeling of distinct CW polysaccharides, including arabinogalactan proteins, whose loss is detrimental to defense, highlighting specific requirements for antagonizing pathogens and potentiating plant defenses. [ABSTRACT FROM AUTHOR]