Phosphoproteomic analysis uncovers phosphorylated proteins in response to salicylic acid and N-hydroxypipecolic acid in Arabidopsis.

BACKGROUND

The phytohormone salicylic acid (SA) serves as a crucial signaling molecule within the realm of plant immunity, playing an indispensable role in both local and systemic acquired resistance (SAR). N-hydroxypipecolic acid (NHP), a derivative of L-lysine, is integral to the induction of SAR. Recent investigations have illuminated the intricate manner in which NHP orchestrates the establishment of SAR in conjunction with the immune signal SA.

METHODS AND RESULTS

To further explore the mechanisms governing the synergistic regulation of SAR by SA and NHP, we conducted an extensive phosphoproteomic analysis aimed at identifying the phosphoproteins modulated either commonly or uniquely by SA and NHP, employing a phosphoproteomics platform built upon high-resolution mass spectrometry. Our study revealed a total of 133 phosphopeptides, derived from 115 distinct proteins, exhibiting exclusive responsiveness to NHP treatment. In contrast, 229 phosphopeptides sourced from 204 proteins demonstrated exclusive sensitivity to SA treatment. Additionally, the phosphorylation status of 215 proteins, including numerous kinases, phosphatases, transcription factors, and proteins implicated in membrane trafficking, was commonly modulated by both SA and NHP.

CONCLUSION

This investigation offers detailed insights into the key phosphoproteins influenced either collectively or specifically by SA and NHP, thereby enabling further exploration of the mechanisms underlying the synergistic regulation of immune responses orchestrated by these two potent molecules.