Dehydration tolerance in apple seedlings is affected by an inhibitor of ABA 8'-hydroxylase CYP707A |
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Authors: | Kondo Satoru Sugaya Sumiko Sugawa Shun Ninomiya Maki Kittikorn Monrudee Okawa Katsuya Ohara Hitoshi Ueno Kotomi Todoroki Yasushi Mizutani Masaharu Hirai Nobuhiro |
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Affiliation: | a Graduate School of Horticulture, Chiba University, Matsudo 271-8510, Japan b Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-0006, Japan c Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan d Faculty of Agriculture, Shizuoka University, Shizuoka 422-8529, Japan e Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan |
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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 (EC50) 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. |
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Keywords: | ABA, abscisic acid Abz-F1, abscinazole-F1 EC50, 50% effective concentration GA, gibberellic acid NCED, 9-cis epoxycarotenoid dioxigenase O2&minus , superoxide PA, phaseic acid PPF, photosynthetic photon flux RH, relative humidity SOD, superoxide dismutase |
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