Abscisic acid (ABA) is a critical plant hormone that plays a pivotal role in drought stress response by acting as a master regulator of water conservation mechanisms. During water scarcity, ABA levels rapidly increase, triggering a cascade of physiological responses designed to minimize water loss and protect plant tissues. The hormone primarily functions by inducing stomatal closure, which dramatically reduces transpiration and prevents excessive water evaporation from leaf surfaces.

At the cellular level, ABA activates specific ion channels and signaling pathways that cause guard cells surrounding stomata to shrink, effectively closing these microscopic pores and limiting water vapor escape. Additionally, the hormone stimulates the expression of genes involved in osmotic adjustment, allowing plant cells to maintain turgor pressure and cellular integrity under dehydration conditions. This sophisticated molecular strategy enables plants to survive prolonged drought periods by conserving water, protecting cellular structures, and maintaining minimal metabolic activities until more favorable conditions return.