NEET BIOLOGY

Detailed explanation-1: -Abscisic acid (ABA) is a phytohormone known as the “stress hormone”. ABA signaling mediates many types of abiotic stresses, such as drought, salinity, heat and cold stress. In roots, ABA plays an essential role in inhibiting cell division and elongation in response to soil conditions.

Detailed explanation-2: -Ethylene inhibits abscisic acid-induced stomatal closure in Arabidopsis. Plant Physiol.

Detailed explanation-3: -Different DNA synthesis inhibitors are efficient in plants: hydroxyurea (HU), mimosine and aphidicolin. HU inhibits the activity of ribonucleotide diphosphate reductase, thus depriving the cells of newly synthesised deoxyribonucleotide triphosphates, consequently preventing DNA replication [19].

Detailed explanation-4: –The main function of abscisic acid in the plant is the regulation of dormancy and abscission (Detachment of leaves or other parts of plant).-Abscisic acid induces dormancy in the plant so that seeds can remain unaffected by factors that are unfavorable for plant growth.

Detailed explanation-5: -The stress hormone abscisic acid (ABA) induces expression of defence genes in many organs, modulates ion homeostasis and metabolism in guard cells, and inhibits germination and seedling growth.