Abstract
Stomata are epidermal pores formed by pairs of specialized guard cells, which regulate gas exchanges between the plant and the atmosphere. Modulation of transcription has emerged as an important level of regulation of stomatal activity. The AtMYB60 transcription factor was previously identified as a positive regulator of stomatal opening, although the details of its function remain unknown. Here, we propose a role for AtMYB60 as a negative modulator of oxylipins synthesis in stomata. The atmyb60-1 mutant shows reduced stomatal opening and accumulates increased levels of 12-oxo-phytodienoic acid (12-OPDA), jasmonic acid (JA) and jasmonoyl-l-isoleucine (JA-Ile) in guard cells. We provide evidence that 12-OPDA triggers stomatal closure independently of JA and cooperatively with abscisic acid (ABA) in atmyb60-1. Our study highlights the relevance of oxylipins metabolism in stomatal regulation and indicates AtMYB60 as transcriptional integrator of ABA and oxylipins responses in guard cells.
Highlights
Stomata are epidermal pores formed by pairs of specialized guard cells, which regulate gas exchanges between the plant and the atmosphere
abscisic acid (ABA) content was diminished in guard cells. atmyb[60-1] stomata showed great variability in ABA accumulation, they did not reveal significant differences compared with the wild type (Fig. 1b)
Despite the predominant role of ABA in regulating stomatal closure in response to water deficit, it is increasingly clear that other hormones, including oxylipins, contribute to modulate stomatal activity under stress
Summary
Stomata are epidermal pores formed by pairs of specialized guard cells, which regulate gas exchanges between the plant and the atmosphere. Modulation of transcription has emerged as an important level of regulation of stomatal activity. The atmyb[60-1] mutant shows reduced stomatal opening and accumulates increased levels of 12-oxo-phytodienoic acid (12-OPDA), jasmonic acid (JA) and jasmonoyl-l-isoleucine (JA-Ile) in guard cells. We provide evidence that 12-OPDA triggers stomatal closure independently of JA and cooperatively with abscisic acid (ABA) in atmyb[60-1]. Our study highlights the relevance of oxylipins metabolism in stomatal regulation and indicates AtMYB60 as transcriptional integrator of ABA and oxylipins responses in guard cells. Additional positive regulators of stomatal closure include jasmonates (JAs) and salicylic acid (SA)[2]. 12-OPDA modulates specific plant responses independently of JA, including gene expression and stomatal a ctivity[5,6,7,8]. The cellular specificity of the AtMYB60 regulation provides a new level of regulation, allowing the precise spatial control of oxylipin-mediated responses
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