Putting the brakes on: abscisic acid as a central environmental regulator of stomatal development

Abstract

376I.376II.378III.378IV.380V.382VI.384VII.385VIII.386387References387 Summary Stomata are produced by a controlled series of epidermal cell divisions. The molecular underpinnings of this process are becoming well understood, but mechanisms that determine plasticity of stomatal patterning to many exogenous and environmental cues remain less clear. Light quantity and quality, vapour pressure deficit, soil water content, and CO2 concentration are detected by the plant, and new leaves adapt their stomatal densities accordingly. Mature leaves detect these environmental signals and relay messages to immature leaves to tell them how to adapt and grow. Stomata on mature leaves may act as stress signal‐sensing and transduction centres, locally by aperture adjustment, and at long distance by optimizing stomatal density to maximize future carbon gain while minimizing water loss. Although mechanisms of stomatal aperture responses are well characterized, the pathways by which mature stomata integrate environmental signals to control immature epidermal cell fate, and ultimately stomatal density, are not. Here we evaluate current understanding of the latter through the influence of the former. We argue that mature stomata, as key portals by which plants coordinate their carbon and water relations, are controlled by abscisic acid (ABA), both metabolically and hydraulically, and that ABA is also a core regulator of environmentally determined stomatal development.

The overexpression of an Amaranthus hypochondriacus NF-YC gene modifies growth and confers water deficit stress resistance in Arabidopsis

“…However, it is feasible to argue that the increased ABA sensitivity observed in AhNF-YC transgenic Arabidopsis plants may have possibly contributed to their enhanced water stress resistance. This proposal is supported by evidence reported in previous studies showing that an augmented resistance to water stress correlated with enhanced ABA sensitivity [61][62][63][64].…”

Stomatal VPD Response: There Is More to the Story Than ABA

“…4). These results strengthen the perception of ABA as the plant's brake system put up by Chater et al (2014): ABA affects physiology and development, transmitting its message via short-and long-distance communication.…”

Origins and Evolution of Stomatal Development

“…Such advances have identified many of the key genetic players responsible for permitting entry into the stomatal lineage, the formation of the meristemoid, and the subsequent divisions and transitions that lead to the formation of stomata (Zhao and Sack, 1999;Ohashi-Ito and Bergmann, 2006;Hara et al, 2007;MacAlister et al, 2007;Pillitteri et al, 2007;Kanaoka et al, 2008;Hunt et al, 2010;Sugano et al, 2010). The activity of the Arabidopsis meristemoid in particular has been shown to be intricately regulated by a multitude of endogenous signaling pathways and environmental cues thereby enabling control over stomatal density and spacing during development (Chater et al, 2014;Lau et al, 2014). Owing to an extensive knowledge base, recent studies in stomatal evolutionary development and physiology invariably call on Arabidopsis to compare and contrast systems when making evolutionary interpretations MacAlister and Bergmann, 2011;Caine et al, 2016).…”

“…It is still unclear as to whether MUTE and FAMA, which act later in the lineage, are also regulated via a MAPK pathway. The development and patterning modules outlined above and in Figure 1H involve probably hundreds, if not thousands, of up-and downstream components for the proper development and maturation of stomata and their neighboring cells and are modulated further by environmental signals and feedback from other hormone pathways (Casson et al, 2009;Chater et al, 2014Chater et al, , 2015Engineer et al, 2014;Lau et al, 2014). Nevertheless, the available molecular evidence strongly indicates that the increasingly complex picture we are uncovering of Arabidopsis stomatal development relies on a core module of genes that was first recruited in some of the earliest land plants, well over 400 million years ago ( Fig.…”