Overexpression of 1-Aminocyclopropane-1-Carboxylic Acid Deaminase (acdS) Gene in Petunia hybrida Improves Tolerance to Abiotic Stresses

Abiotic stress induces the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) in plants, which consequently enhances ethylene production and inhibits plant growth. The bacterial ACC deaminase enzyme encoded by the acdS gene reduces stress-induced ethylene production and improves plant growth in response to stress. In this study, overexpression of acdS in Petunia hybrida (‘Mirage Rose’) significantly reduced expression of the ethylene biosynthesis gene ACC oxidase 1 (ACO1) and ethylene production relative to those in wild type (WT) under various abiotic stresses (cold, drought, and salt). The higher reduction of stress-induced ethylene in the transgenic plants, which was due to the overexpression of acdS, led to a greater tolerance to the stresses compared to that in the WT plants. The greater stress tolerances were proven based on better plant growth and physiological performance, which were linked to stress tolerance. Moreover, expression analysis of the genes involved in stress tolerance also supported the increased tolerance of transgenics relative to that with the WT. These results suggest the possibility that acdS is overexpressed in ornamental plants, particularly in bedding plants normally growing outside the environment, to overcome the deleterious effect of ethylene on plant growth under different abiotic stresses. The development of stress-tolerant plants will be helpful to advance the floricultural industry.