Proteomic Analysis of Ubiquitinated Proteins in Rice (Oryza sativa) After Treatment With Pathogen-Associated Molecular Pattern (PAMP) Elicitors

Authors

Xiao-Lin Chen, Chinese Academy of Agricultural Sciences
Xin Xie, Chinese Academy of Agricultural Sciences
Liye Wu, Chinese Academy of Agricultural Sciences
Caiyun Liu, Huazhong Agricultural University
Lirong Zeng, University of Nebraska-LincolnFollow
Xueping Zhou, Chinese Academy of Agricultural Sciences
Feng Luo, Clemson University
Guo-Liang Wang, Ohio State UniversityFollow
Wende Liu, Chinese Academy of Agricultural SciencesFollow

Date of this Version

2018

Citation

Front. Plant Sci. 9:1064.

Comments

Copyright © 2018 Chen, Xie, Wu, Liu, Zeng, Zhou, Luo, Wang and Liu.

Open access

doi: 10.3389/fpls.2018.01064

Abstract

Reversible protein ubiquitination plays essential roles in regulating cellular processes. Although many reports have described the functions of ubiquitination in plant defense responses, few have focused on global changes in the ubiquitome. To better understand the regulatory roles of ubiquitination in rice pattern-triggered immunity (PTI), we investigated the ubiquitome of rice seedlings after treatment with two pathogen-associated molecular patterns, the fungal-derived chitin or the bacterialderived flg22, using label-free quantitative proteomics. In chitin-treated samples, 144 and 167 lysine-ubiquitination sites in 121 and 162 proteins showed increased and decreased ubiquitination, respectively. In flg22-treated samples, 151 and 179 lysine-ubiquitination sites in 118 and 166 proteins showed increased and decreased ubiquitination, respectively. Bioinformatic analyses indicated diverse regulatory roles of these proteins. The ubiquitination levels of many proteins involved in the ubiquitination system, protein transportation, ligand recognition, membrane trafficking, and redox reactions were significantly changed in response to the elicitor treatments. Notably, the ubiquitination levels of many enzymes in the phenylpropanoid metabolic pathway were up-regulated, indicating that this pathway is tightly regulated by ubiquitination during rice PTI. Additionally, the ubiquitination levels of some key components in plant hormone signaling pathways were up- or down-regulated, suggesting that ubiquitination may fine-tune hormone pathways for defense responses. Our results demonstrated that ubiquitination, by targeting a wide range of proteins for degradation or stabilization, has a widespread role in modulating PTI in rice. The large pool of ubiquitination targets will serve as a valuable resource for understanding how the ubiquitination system regulates defense responses to pathogen attack.