BIOMOLECULES AND ENZYMES

Detailed explanation-1: -Abscisic acid (ABA) is a stress hormone that accumulates under different abiotic and biotic stresses. A typical effect of ABA on leaves is to reduce transpirational water loss by closing stomata and parallelly defend against microbes by restricting their entry through stomatal pores.

Detailed explanation-2: -ABA is a key hormone that regulates water status and stomatal movement. Under drought conditions, plants produce and accumulate increased amounts of ABA in the guard cells, and this induces stomatal closure to conserve water.

Detailed explanation-3: -Abscisic acid (ABA) is a plant hormone involved in the response of plants to reduced water availability. Reduction of guard cell turgor by ABA diminishes the aperture of the stomatal pore and thereby contributes to the ability of the plant to conserve water during periods of drought.

Detailed explanation-4: -ABA activates the efflux of Ca2+ from internal stores, the activation of S-type and R-type anion channels leading to the efflux of Cl−, malate2−, and NO 3-, the activation of GORK channel, which leads to the efflux of K+ and consequently to the closing of stomatal pores.

Detailed explanation-5: -ABA is also known as the stress hormone because it protects plants from adverse conditions. ABA causes the stomatal closing under the water stress conditions.