# Quantitative Proteomic Analysis of Lysine Malonylation in Response to Salicylic Acid in the Roots of Platycodon grandiflorus

## TL;DR

This study explores how salicylic acid affects lysine malonylation in the roots of Platycodon grandiflorus, revealing its role in plant metabolism and stress response.

## Contribution

The first comprehensive quantitative proteomic analysis of lysine malonylation in Platycodon grandiflorus roots after salicylic acid treatment.

## Key findings

- Salicylic acid treatment altered lysine malonylation levels in 798 modification sites across 414 proteins.
- Malonylation was primarily linked to photosynthesis and carbon metabolism pathways.
- Salicylic acid increased malondialdehyde and enzyme activity but did not affect saponin content.

## Abstract

Salicylic acid, as a plant hormone, significantly affects the physiological and biochemical indexes of soluble sugar, malondialdehyde content, peroxidase, and superoxide dismutase enzyme activity in Platycodon grandiflorus. Lysine malonylation is a post-translational modification that involves various cellular functions in plants, though it is rarely studied, especially in medicinal plants. In this study, the aim was to perform a comparative quantitative proteomic study of malonylation modification on P. grandiflorus root proteins after salicylic acid treatment using Western blot with specific antibodies, affinity enrichment and LC-MS/MS analysis methods. The analysis identified 1907 malonyl sites for 809 proteins, with 414 proteins and 798 modification sites quantified with high confidence. Post-treatment, 361 proteins were upregulated, and 310 were downregulated. Bioinformatics analysis revealed that malonylation in P. grandiflorus is primarily involved in photosynthesis and carbon metabolism. Physiological and biochemical analysis showed that salicylic acid treatment increased the malondialdehyde levels, soluble protein, superoxide dismutase, and peroxidase activity but did not significantly affect the total saponins content in P. grandiflorus. These findings provide an important basis for exploring the molecular mechanisms of P. grandiflorus following salicylic acid treatment and enhance understanding of the biological function of protein lysine malonylation in plants.