Fuente: WIPO "tomato" In alternative embodiments, provided are compositions and methods for manipulating the exchange of water and/or carbon dioxide (CO2) through plant stomata comprising the step of modulating the expression of CO2 sensor genes and the redundant MAP kinases MPK4/MPK12, and HT1 protein kinase, and their genes. In alternative embodiments, provided are dominant active HT1 mutants that cause a high CO2-insensitive constitutively open stomatal phenotype. In alternative embodiments, the invention provides plants, and plant tissues, having increased water use efficiency, and drought-resistant plants, plant tissues and cells; and methods for engineering of water transpiration and water use efficiency in plants, and engineering plants with increased water use efficiency and drought-resistant plants, plant tissues and cells. For plants grown in humid regions with sufficient water availability, down-regulation of the CO2 sensor proteins provides plants that show less stomatal closing in light of the atmospheric CO2 increase for enabling enhanced CO2 influx into leaves.