Stomatal regulation of plant water status

Stomata rapidly and slowly respond to a range of abiotic stress, regulating water status. Under water-sufficient conditions, the majority of water loss in plants occurs through open stomata. Under environmental conditions that cause stomata to close, such as during drought, water loss is mainly executed via solid-phase cuticular transpiration. The diffusional resistance of the transpiration pathway consists of two varying components: the leaf stomatal resistance and the leaf boundary layer resistance. Dehydration avoidance mechanisms involve the maintenance of a high (favorable) plant water status during stress. Many cacti, orchids, bromeliads, and other succulent plants with crassulacean acid metabolism (CAM) have stomatal activity patterns that contrast with those found in C3 and C4 plants. Tolerance to low water potentials requires maintaining plant functions under limited water availability and/or the rapid recovery of plant water status and plant function after stress.