Regulation of stomatal density by the GTL1 transcription factor for improving water use efficiency.

A stoma (pl. stomata) is the pore formed by two guard cells found predominantly in the leaf epidermis. Plants control stomatal aperture (opening and closing) and/or number (density) to regulate carbon dioxide (CO2) uptake and water loss (transpiration), which is necessary to optimize plant growth, development, and fitness in response to various environmental conditions. Recently, we identified Arabidopsis GT2-LIKE 1 (GTL1) as a transcriptional repressor of STOMATAL DENSITY AND DISTRIBUTION 1 (SDD1), a negative regulator of stomatal density. GTL1 directly interacts with the SDD1 promoter regulating stomatal density, transpiration, and water use efficiency (WUE). Here we discuss potential GTL1 orthologs in other plant species.