Transcription Factors and Hormone-Mediated Mechanisms Regulate Stomata Development and Responses UnderAbiotic Stresses: An Overview

Plants require essentially carbon dioxide (CO2) and water to survive. However, CO2 uptake implicates leaf water loss due to transpiration, and it is thus necessary that plants finely regulate their gas exchanges to maintain an optimal trade-off between photosynthetic rate and water loss. Plants evolved stomata more than 410 million years ago, a change that allowed them to regulate water loss due to transpiration during the uptake of CO2 for photosynthesis. Stomata are specialized epidermal structures made up by two guard cells (GCs), whose movement is turgor-driven, around a pore. Gas exchange is regulated by controlling the aperture of the stomatal pore: an open stoma allows the plant to take CO2 to perform photosynthesis; in the meantime the plant loses water along with oxygen and to avoid desiccation the stoma is closed. Environmental signals such as light intensity, the concentration of atmospheric CO2 and endogenous plant hormones are integrated into specific developmental programs to modulate stomatal formation or function in response to changes in the surrounding conditions. Genes controlling cell-fate specification, cell polarity, cell division and cell-cell communication during stomatal development and movement have been identified through investigations of many Arabidopsis mutants with an impaired stomatal pattern or morphological defects. The perception of an abiotic stress triggers the activation of signal transduction cascades that interact with or are activated by hormones. Among these, abscisic acid (ABA) is the best-known stress hormone that leads to closure of stomata. In this review, we update the current knowledge about the genetic regulation of stomata development and also we deepen the stomata’s behavior of plants subjected to water stress (drought and salinity) and waterlogging.