Abiotic stresses impair crop production on irrigated land worldwide. Overall, the susceptibility or
tolerance to the stress in plants is a coordinated action of multiple stress responsive genes, which also cross-talk
with other components of stress signal transduction pathways. Plant responses to abiotic stress can be determined
by the severity of the stress and by the metabolic status of the plant. Abscisic acid (ABA) is a phytohormone
critical for plant growth and development and plays an important role in integrating various stress signals and
controlling downstream stress responses. Plants have to adjust ABA levels constantly in response to changing
physiological, metabolic and environmental conditions. To date, the mechanisms for fine-tuning of ABA levels
remain elusive. The mechanisms by which plants respond to abiotic stresses include both ABA-dependent and
ABA-independent processes. Various transcription factors such as DREB2A/2B, AREB1, RD22BP1 and
MYC/MYB are known to regulate the ABA-responsive gene expression by interacting with their corresponding
cis-acting elements such as DRE/CRT, ABRE, and MYCRS/MYBRS, respectively. Due to polygenic nature of
the trait, it is becoming important to apply genome wide tools for precise understanding of the mechanisms and to
ultimately improve stress tolerance in crops plants. This chapter describes the ABA-induced stress response
pathway and the application of ‘omics’ technologies to unravel the complex mechanisms governing abiotic stress
tolerance in plants.
