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

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 <i>Platycodon grandiflorus</i>. 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 <i>P. grandiflorus</i> 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 <i>P. grandiflorus</i> 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 <i>P. grandiflorus</i>. These findings provide an important basis for exploring the molecular mechanisms of <i>P. grandiflorus</i> following salicylic acid treatment and enhance understanding of the biological function of protein lysine malonylation in plants.