This article discusses the molecular mechanisms underlying plant responses to water stress, focusing on signal transduction pathways and gene expression. Water stress, which includes drought, high salinity, and cold conditions, triggers various biochemical and physiological responses in plants. The plant hormone abscisic acid (ABA) plays a key role in stress tolerance, and many genes are induced in response to water stress. These genes are involved in protecting cells from water deficit and regulating signal transduction in the water-stress response. The expression of water-stress-inducible genes is complex, with some responding rapidly to stress and others being induced after the accumulation of ABA. Many of these genes are also induced by exogenous ABA, suggesting the existence of both ABA-dependent and ABA-independent signal transduction pathways. Promoter analysis has identified several cis-acting elements involved in ABA-dependent and ABA-independent responses to water stress. The article reviews recent progress in understanding the signal transduction cascades leading to the expression of water-stress-inducible genes. It discusses possible sensors of osmotic stress in plants, based on knowledge of yeast and bacterial sensors. A glossary of terms is included to facilitate reading. The functions of water-stress-inducible genes are classified into two groups: those involved in stress tolerance and those involved in signal transduction and gene expression. These genes include proteins that protect cells from water deficit, as well as regulatory proteins that function in stress response. The regulation of gene expression by water stress is discussed, with a focus on ABA-responsive gene expression. The article describes several signal transduction pathways involved in the water-stress response, including ABA-dependent and ABA-independent pathways. These pathways involve various proteins, such as bZIP, MYC, and MYB transcription factors, as well as protein kinases and PLC. The article also discusses the role of second messengers, such as Ca²+ and IP3, in signal transduction during water stress. These second messengers are involved in various cellular processes, including stomata closure and ion transport. The role of ABA in signal transduction is also discussed, with a focus on its involvement in gene expression and physiological responses during water stress. The article concludes with a discussion of the molecular mechanisms underlying water-stress responses, including the role of various signaling factors and the importance of understanding these mechanisms for improving plant tolerance to water stress.This article discusses the molecular mechanisms underlying plant responses to water stress, focusing on signal transduction pathways and gene expression. Water stress, which includes drought, high salinity, and cold conditions, triggers various biochemical and physiological responses in plants. The plant hormone abscisic acid (ABA) plays a key role in stress tolerance, and many genes are induced in response to water stress. These genes are involved in protecting cells from water deficit and regulating signal transduction in the water-stress response. The expression of water-stress-inducible genes is complex, with some responding rapidly to stress and others being induced after the accumulation of ABA. Many of these genes are also induced by exogenous ABA, suggesting the existence of both ABA-dependent and ABA-independent signal transduction pathways. Promoter analysis has identified several cis-acting elements involved in ABA-dependent and ABA-independent responses to water stress. The article reviews recent progress in understanding the signal transduction cascades leading to the expression of water-stress-inducible genes. It discusses possible sensors of osmotic stress in plants, based on knowledge of yeast and bacterial sensors. A glossary of terms is included to facilitate reading. The functions of water-stress-inducible genes are classified into two groups: those involved in stress tolerance and those involved in signal transduction and gene expression. These genes include proteins that protect cells from water deficit, as well as regulatory proteins that function in stress response. The regulation of gene expression by water stress is discussed, with a focus on ABA-responsive gene expression. The article describes several signal transduction pathways involved in the water-stress response, including ABA-dependent and ABA-independent pathways. These pathways involve various proteins, such as bZIP, MYC, and MYB transcription factors, as well as protein kinases and PLC. The article also discusses the role of second messengers, such as Ca²+ and IP3, in signal transduction during water stress. These second messengers are involved in various cellular processes, including stomata closure and ion transport. The role of ABA in signal transduction is also discussed, with a focus on its involvement in gene expression and physiological responses during water stress. The article concludes with a discussion of the molecular mechanisms underlying water-stress responses, including the role of various signaling factors and the importance of understanding these mechanisms for improving plant tolerance to water stress.