Protein Phosphorylation Changes During Systemic Acquired Resistance in Arabidopsis thaliana

Abstract

Systemic acquired resistance (SAR) in plants is a defense response that provides resistance against a wide range of pathogens at the whole-plant level following primary infection. Although the molecular mechanisms of SAR have been extensively studied in recent years, the role of phosphorylation that occurs in systemic leaves of SAR-induced plants is poorly understood. We used a data-independent acquisition (DIA) phosphoproteomics platform based on high-resolution mass spectrometry in an Arabidopsis thaliana model to identify phosphoproteins related to SAR establishment. A total of 8011 phosphorylation sites from 3234 proteins were identified in systemic leaves of Pseudomonas syringae pv. maculicola ES4326 (Psm ES4326) and mock locally inoculated plants. A total of 859 significantly changed phosphoproteins from 1119 significantly changed phosphopeptides were detected in systemic leaves of Psm ES4326 locally inoculated plants, including numerous transcription factors and kinases. A variety of defense response-related proteins were found to be differentially phosphorylated in systemic leaves of Psm ES4326 locally inoculated leaves, suggesting that these proteins may be functionally involved in SAR through phosphorylation or dephosphorylation. Significantly changed phosphoproteins were enriched mainly in categories related to response to abscisic acid, regulation of stomatal movement, plant–pathogen interaction, MAPK signaling pathway, purine metabolism, photosynthesis-antenna proteins, and flavonoid biosynthesis. A total of 28 proteins were regulated at both protein and phosphorylation levels during SAR. RT-qPCR analysis revealed that changes in phosphorylation levels of proteins during SAR did not result from changes in transcript abundance. This study provides comprehensive details of key phosphoproteins associated with SAR, which will facilitate further research on the molecular mechanisms of SAR.

Extracellular vesicles: Their functions in plant–pathogen interactions

“…The plant PTI is activated by the recognition of PAMPs and PRRs, which are mainly RLKs (Wu et al, 2019). In our recent study, we found the phosphorylation levels of 17 RLKs were significantly changed in systemic leaves of SAR-induced plants (Zhou et al, 2021), suggesting that these proteins are also involved in SAR establishment in cells of systemic leaves. Therefore, we can speculate that plant EVs also contain PAMPs released by the pathogens, which contribute to the induction of local resistance and SAR (Figure 2).…”

(De)Activation (Ir)Reversibly or Degradation: Dynamics of Post-Translational Protein Modifications in Plants

“…In this study, a marked increase in the number of differentially phosphorylated proteins in systemic leaves inoculated with the pathogenic bacteria Pseudomonas syringae pv. Maculicola was observed [30]. The observed differentially phosphorylated proteins included several transcription factors, kinases, and a variety of defense response-related proteins.…”

Lipid transfer proteins involved in plant–pathogen interactions and their molecular mechanisms

“…ACQUIRED RE S IS TAN CE SAR is an inducible defensive response of plants triggered by localized pathogen attack. It can induce immunity to subsequent pathogen infection in the whole plant within a few days (Schnake et al, 2020;Zhou et al, 2021). Some long-distance signals synthesized at the infection site during SAR can be translocated to systemic tissues via phloem or volatilization to induce disease resistance (Chanda et al, 2011;Chaturvedi et al, 2012;Jung et al, 2009;Riedlmeier et al, 2017).…”