Lipid-mediated regulation of stomatal dynamics during plant stress responses.

Stomatal regulation is governed by interconnected developmental, hormonal, metabolic, and environmental signaling networks that enable plants to balance carbon acquisition with water conservation. This review highlights lipid metabolism and lipid-mediated signaling as an emerging regulatory layer integrating these processes during stomatal development and movement. We synthesize evidence that diverse lipid classes, including fatty acids, sterols, phosphoinositides, phosphatidic acid (PA), diacylglycerol (DAG), sphingolipids, and oxylipins, function not only as membrane components but also as dynamic metabolic and signaling regulators in guard cells. A central conclusion is that lipid flux, rather than lipid abundance alone, provides a flexible regulatory interface linking environmental and hormonal cues to guard-cell signaling and stomatal behavior. In particular, PA-DAG metabolism integrates ABA, ROS, Ca²⁺, and ion-transport pathways during stress-induced stomatal closure, whereas triacylglycerol turnover supplies metabolic substrates that support blue-light-induced stomatal opening. Lipid metabolism also intersects with the SPCH-MUTE-FAMA-dependent developmental program, linking lipid homeostasis to stomatal differentiation and environmental plasticity. Key gaps remain in understanding the spatial and temporal dynamics of lipid signaling, the specificity of individual lipid species, and their crosstalk with hormonal, ROS, Ca²⁺, and ion-transport networks. Clarifying these mechanisms will advance our understanding of how lipid metabolism coordinates stomatal responses and may provide new opportunities to improve plant stress resilience.