The AtMYB60 transcription factor regulates stomatal opening by modulating oxylipin synthesis in guard cells

Stomata are epidermal pores formed by pairs of specialized guard cells, which regulate gas exchangesbetween the plant and the atmosphere. Modulation of transcription has emerged as an importantlevel of regulation of stomatal activity. The AtMYB60 transcription factor was previously identified as apositive regulator of stomatal opening, although the details of its function remain unknown. Here, wepropose a role for AtMYB60 as a negative modulator of oxylipins synthesis in stomata. The atmyb60-1mutant shows reduced stomatal opening and accumulates increased levels of 12-oxo-phytodienoicacid (12-OPDA), jasmonic acid (JA) and jasmonoyl-l-isoleucine (JA-Ile) in guard cells. We provideevidence that 12-OPDA triggers stomatal closure independently of JA and cooperatively with abscisicacid (ABA) in atmyb60-1. Our study highlights the relevance of oxylipins metabolism in stomatalregulation and indicates AtMYB60 as transcriptional integrator of ABA and oxylipins responses inguard cells.