Dehydration tolerance in apple seedlings is affected by an inhibitor of ABA 8'-hydroxylase CYP707A.

Abstract

The effects of an abscisic acid (ABA) 8'-hydroxylase inhibitor (Abz-F1) on ABA catabolism, stomatal aperture, and water potential were examined in apple seedlings under dehydration and rehydration conditions. In this study, 9-cis-epoxycarotenoid dioxigenase (MdNCED) and ABA 8'-hydroxylase (MdCYP707A) genes were isolated and their expressions were investigated under dehydration and rehydration conditions. The stomatal aperture decreased up to 4 h after spraying with Abz-F1 and the stomatal aperture in the Abz-F1-treated leaves was generally lower than that in the untreated control-leaves during the dehydration condition. Although the water potential in untreated control-leaves decreased with the progress of dehydration, it was maintained at a higher level in the Abz-F1 treated-leaves than in the untreated control-leaves during dehydration. Endogenous ABA concentrations increased with dehydration in both the Abz-F1 treated- and untreated-control-leaves, but the ABA levels in the Abz-F1 treated-leaves were higher than those in the untreated control-leaves throughout dehydration. In contrast, the phaseic acid (PA) concentrations in the Abz-F1 treated-leaves were lower than those in the untreated control-leaves during dehydration. The expressions of MdNCEDs in the Abz-F1 treated-leaves were lower than those in the untreated control-leaves regardless of the higher endogenous ABA concentrations. Moreover, the expressions of MdCYP707As in the Abz-F1 treated-leaves were also lower than those in the untreated control-leaves. Higher 50% effective concentrations (EC(50)) and ascorbic acid concentrations were observed in the Abz-F1 treated-leaves, which show that the oxidative damage under dehydration may be reduced by Abz-F1 application. These results suggest that prompt stomata closure is required for survival under dehydration, and Abz-F1 application may therefore be of practical use. The increase of endogenous ABA, which induced prompt stomata closure in Abz-F1 treated-leaves may depend on inhibition of the expression of MdCYP707As. Furthermore, the results showed the close relationship between MdNCEDs and MdCYP707As on ABA catabolism.

• Authors: Satoru Kondo, Sumiko Sugaya, Shun Sugawa, Maki Ninomiya, Monrudee Kittikorn, Katsuya Okawa, Hitoshi Ohara, Kotomi Ueno, Yasushi Todoroki, Masaharu Mizutani, Nobuhiro Hirai
• Journal: Journal of plant physiology (J Plant Physiol) Vol. 169 Issue 3 Pg. 234-41 (Feb 15 2012) ISSN: 1618-1328 [Electronic] Germany
• PMID: 22024733 (Publication Type: Journal Article)
• Copyright: Copyright © 2011. Published by Elsevier GmbH.

Chemical References

• Cytochrome P-450 Enzyme Inhibitors
• Enzyme Inhibitors
• Plant Growth Regulators
• Plant Proteins
• Water
• Abscisic Acid
• Cytochrome P-450 Enzyme System
• abscisic acid 8'-hydroxylase

Topics

• Abscisic Acid (metabolism)
• Cytochrome P-450 Enzyme Inhibitors
• Cytochrome P-450 Enzyme System (metabolism)
• Dehydration (metabolism)
• Enzyme Inhibitors (metabolism)
• Malus (growth & development, metabolism)
• Plant Growth Regulators (metabolism)
• Plant Proteins
• Seedlings (growth & development, metabolism)
• Water (metabolism)