ABA Regulation of Plant Responses to Drought and Salt Stresses

The phytohormone abscisic acid (ABA) plays an essential role in the abiotic stress response and tolerance of plants, especially during water-related stresses. Thus, ABA is also known as a plant stress hormone. In response to drought and/or salinity stresses, the expression of many ABA-responsive genes is16.1 induced. Several transcription factors and their corresponding DNA target sequences have been identified to control this biological response on the molecular level. Drought stress can directly induce ABA biosynthesis, transportation, and release from its storage form. The activity of ion channels, located on the guard cell membrane, is modulated by drought and/or salinity stresses to regulate stomata movement, which can be simulated by treatment with ABA. In this chapter, we focus on the ABA regulation of drought and salt responses in plants, examining gene expression, stress signaling, and ion homeostasis under these stresses.