ABA is a derivative of:

The plant growth regulators (PGRs) are small, simple molecules of diverse chemical composition. They could be indole compounds (Indole-3-acetic acid, IAA); adenine derivatives (N6-furfurylamino purine, kinetin), derivatives of carotenoids (abscisic acid, ABA); terpenes (gibberellic acid, GA3) or gases (ethylene, C2H4).