Articles
DEHYDRATION TOLERANCE IN APPLE SEEDLINGS IS ADVANCED BY RETARDING ABA 8′-HYDROXYLASE CYP707A
Article number
1042_18
Pages
151 – 157
Language
English
Abstract
The effects of an abscisic acid (ABA) 8-hydroxylase inhibitor (ABAI) on ABA catabolism, stomatal aperture, and water potential were investigated in apple seed-lings under dehydration conditions.
In addition, 9-cis-epoxycarotenoid dioxygenase (MdNCED) and ABA 8-hydroxylase (MdCYP707A) genes were isolated and their expressions were analyzed under dehydration conditions.
The stomatal aperture decreased for 4 h after spraying with ABAI and the stomatal aperture in the ABAI- treated leaves was lower than that in the untreated control- leaves during the dehydra¬tion conditions.
The water potential was maintained at a higher level in the ABAI- treated leaves during dehydration, however that in untreated control-leaves decreased with the progress of dehydration.
In both the ABAI-treated and untreated control- leaves, endogenous ABA concentrations increased with dehydration, but the ABA levels in the ABAI-treated leaves were higher than those in the untreated control- leaves throughout dehydration.
In contrast, the phaseic acid (PA) concentrations in the ABAI-treated leaves were lower than those in the untreated control-leaves during dehydration.
Regardless of the higher endogenous ABA concentrations, the expres¬sions of MdNCEDs in the ABAI-treated leaves were lower than those in the untreated control-leaves.
In addition, the expressions of MdCYP707As in the ABAI-treated leaves were also lower than those in the untreated control-leaves.
Higher 50% effective concentrations (EC50) were observed in the ABAI-treated leaves, which suggests that the oxidative damage under dehydration may be reduced by ABAI application.
The results suggest that prompt stomata closure is required for survival under dehydra¬tion, and ABAI application may therefore be of practical use.
The increase of endogenous ABA, which induced prompt stomata closure in ABAI-treated leaves, may depend on the retardation of the expression of MdCYP707As.
Moreover, the results demonstrate a close relationship between MdNCEDs and MdCYP707As on ABA catabolism.
In addition, 9-cis-epoxycarotenoid dioxygenase (MdNCED) and ABA 8-hydroxylase (MdCYP707A) genes were isolated and their expressions were analyzed under dehydration conditions.
The stomatal aperture decreased for 4 h after spraying with ABAI and the stomatal aperture in the ABAI- treated leaves was lower than that in the untreated control- leaves during the dehydra¬tion conditions.
The water potential was maintained at a higher level in the ABAI- treated leaves during dehydration, however that in untreated control-leaves decreased with the progress of dehydration.
In both the ABAI-treated and untreated control- leaves, endogenous ABA concentrations increased with dehydration, but the ABA levels in the ABAI-treated leaves were higher than those in the untreated control- leaves throughout dehydration.
In contrast, the phaseic acid (PA) concentrations in the ABAI-treated leaves were lower than those in the untreated control-leaves during dehydration.
Regardless of the higher endogenous ABA concentrations, the expres¬sions of MdNCEDs in the ABAI-treated leaves were lower than those in the untreated control-leaves.
In addition, the expressions of MdCYP707As in the ABAI-treated leaves were also lower than those in the untreated control-leaves.
Higher 50% effective concentrations (EC50) were observed in the ABAI-treated leaves, which suggests that the oxidative damage under dehydration may be reduced by ABAI application.
The results suggest that prompt stomata closure is required for survival under dehydra¬tion, and ABAI application may therefore be of practical use.
The increase of endogenous ABA, which induced prompt stomata closure in ABAI-treated leaves, may depend on the retardation of the expression of MdCYP707As.
Moreover, the results demonstrate a close relationship between MdNCEDs and MdCYP707As on ABA catabolism.
Authors
S. Kondo, S. Sugaya, M. Kittikorn, Y. Todoroki, M. Mizutani, N. Hirai
Keywords
ABA metabolism, 9-cis-epoxycarotenoid dioxygenase, Malus ×domestica, water stress
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