|Authors: ||L.W. Wang, X.X. Li, Y. Todoroki, S. Kondo|
|Keywords: ||apple, abscisic acid, proline, water potential, antioxidant enzyme activity|
The effects of abscisic acid (ABA) and abscinazole (Abz-E3M), an inhibitor of ABA 8'-hydroxylase, on drought stress were examined in apple seedlings.
ABA, Abz-E3M, and a combination of both (ABA+Abz) were sprayed onto seedlings.
The water potential, malonaldehyde (MDA) and proline concentrations, antioxidant enzyme activities such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and peroxidase (POD), endogenous ABA concentrations, and expressions of the 9-cis-epoxycarotenoid dioxygenase (MdNCED1) gene were analyzed.
Drought conditions reduced water potential (Mpa) in the leaves but increased proline accumulation, ABA concentrations, and MdNCED1 expression.
The activities of SOD, CAT, APX, and POD in ABA+Abz or ABA treated leaves increased at 4 DAT after the imposition of drought conditions.
The ABA+Abz treatment maintained water potential and reduced proline concentration but increased 2,2-diphenyl-1-picryldrazyl (DPPH) radical scavenging activity, SOD, and APX activity.
ABA+Abz had a stronger effect than the application of ABA alone on water potential (ABA+Abz at -1.76 MPa; ABA at -1.95 MPa), ABA concentrations (ABA+Abz of 867.3 μg kg‑1 FW; ABA of 175.1 μg kg‑1 FW) and proline concentrations (ABA+Abz of 0.52 nmol kg‑1 FW; ABA of 0.68 nmol kg‑1 FW at ABA). The results suggest that the combined ABA+Abz treatment increased endogenous ABA concentrations, maintained leaf water potential and increased antioxidant activities, and as a result may induce tolerance against drought stress.
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