Insight into abscisic acid perception and signaling to increase plant tolerance to abiotic stress

As changes occur in climate, abiotic stress to agricultural production is an inevitable threat to farmers' ability to meet an increasing demand to feed people. Plants have developed a stress tolerance mechanism to reduce the effects of such environmental conditions by engaging various stress-responsive genes. Accordingly, various signal transduction networks are used to fabricate stress tolerance. Engineering of the phytohormone abscisic acid (ABA) could be a choice method for scientists to mitigate abiotic stress because of its widespread role in response to salt, drought, heat, and cold stresses including triggering stomatal regulation and leaf senescence. In addition, it plays a crucial role in seed maturation, seed dormancy, stomatal opening/closure and increases resistance against pathogens through callose depositions and regulates physiological strategies in stress signaling pathways through synchronizing of hormonal crosstalk. The transcriptional regulation can be achieved through ABA-dependent and ABA-independent signaling cascades. ABAI5 and RD29A genes are regulated in ABA-dependent and independent manners to mitigate stress tolerance. ABA regulatory components (RCARs) including pyrabactin resistance PYR/PYL genes, SnRK2 type protein kinases, transcription factors (WRKY, NAC, AREB1, bZIP, RGL2, and ABRE), reactive oxygen species, jasmonic acid and cytokinin hormones regulate ABA gene action in response to abiotic stresses.