Abscisic Acid (Dormin) is a plant hormone.

Abscisic acid (ABA) is a plant hormone and plays an important role in regulating plant growth and development such as germination, seedling growth, lateral root development, seed development and seed dormancy [1].

ABA is a plant hormone and plays an important role in abiotic stress tolerance. Histone H2B monoubiquitination regulated ABA levels in developing seeds. H2B ubiquitination and ABA dependent chromatin remodeling regulated seed dormancy. Abiotic stress-induced ABA regulated stressresponsive gene expression and stomatal response [1]. In Arabidopsis thaliana seedlings, ABA increased the biosynthesis of certain amino acids and raffinose family oligosaccharides and down-regulated genes that involved in the reorganization of cell walls. Also, ABA increased the levels of α-tocopherol and L-ascorbic acid, which were antioxidants. These results suggested that ABA induced crosstalk between pathways regulating redox homeostasis and metabolic pathways [2]. In leaves of maize, ABA attenuated UV-B-induced damage and maintained cell homeostasis through activation of NADPH oxidase (pNOX) and increase of H2O2 and NO production [3].

References:
[1].  Chinnusamy V, Gong Z, Zhu JK. Abscisic acid-mediated epigenetic processes in plant development and stress responses. J Integr Plant Biol, 2008, 50(10): 1187-1195.
[2].  Ghassemian M, Lutes J, Chang HS, et al. Abscisic acid-induced modulation of metabolic and redox control pathways in Arabidopsis thaliana. Phytochemistry, 2008, 69(17): 2899-2911.
[3].  Tossi V, Lamattina L, Cassia R. An increase in the concentration of abscisic acid is critical for nitric oxide-mediated plant adaptive responses to UV-B irradiation. New Phytol, 2009, 181(4): 871-879.