ABA-dependent and ABA-independent signaling in response to osmotic stress in plants

• AREB/ABFs are predominant transcription factors in ABA-dependent gene expression.
• DREB2A is a key transcription factor in ABA-independent osmotic-stress response.
• Various proteins play signal transduction roles during plant adaptation to stress.
• Crosstalk occurs between ABA-dependent and ABA-independent pathways.

Plants have adaptive robustness to osmotic stresses such as drought and high salinity. Numerous genes functioning in stress response and tolerance are induced under osmotic conditions in diverse plants. Various signaling proteins, such as transcription factors, protein kinases and phosphatases, play signal transduction roles during plant adaptation to osmotic stress, with involvement ranging from stress signal perception to stress-responsive gene expression. Recent progress has been made in analyzing the complex cascades of gene expression during osmotic stress response, and especially in identifying specificity and crosstalk in abscisic acid (ABA)-dependent and ABA-independent signaling pathways. In this review, we highlight transcriptional regulation of gene expression governed by two key transcription factors: AREB/ABFs and DREB2A operating respectively in ABA-dependent and ABA-independent signaling pathways.