Loik M. E., Nobel P. S., Exogenous Abscisic Acid Mimics Cold Acclimation for Cacti Differing in Freezing Tolerance, Plant Physiology, 1993, 103(3):871-876, doi: 10.1104/pp.103.3.871
The study compares the responses of three prickly pears to cold, externally applied ABA and experimentally maintained hydration. It presents acclimation signalling, with a particularly strong response in Opuntia fragilis.