Identification of an abscisic acid transporter by functional screening using the receptor complex as a sensor
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Date
2012-06-12
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Abstract
Movement of the plant hormone abscisic acid (ABA) within plants has been documented; however, the molecular mechanisms that regulate ABA transport are not fully understood. By using a modified yeast two-hybrid system, we screened Arabidopsis cDNAs capable of inducing interactions between the ABA receptor PYR/PYL/ RCAR and PP2C protein phosphatase under low ABA concentrations. By using this approach, we identified four members of the NRT1/PTR family as candidates for ABA importers. Transport assays in yeast and insect cells demonstrated that at least one of the candidates ABA-IMPORTING TRANSPORTER (AIT) 1, which had been characterized as the low-affinity nitrate transporter NRT1.2, mediates cellular ABA uptake. Compared with WT, the ait1/nrt1.2 mutants were less sensitive to exogenously applied ABA during seed germination and/or postgermination growth, whereas overexpression of AIT1/NRT1.2 resulted in ABA hypersensitivity in the same conditions. Interestingly, the inflorescence stems of ait1/ nrt1.2 had a lower surface temperature than those of the WT because of excess water loss from open stomata. We detected promoter activities of AIT1/NRT1.2 around vascular tissues in inflorescence stems, leaves, and roots. These data suggest that the function of AIT1/NRT1.2 as an ABA importer at the site of ABA biosynthesis is important for the regulation of stomatal aperture in inflorescence stems.
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Guard cells, Liquid chromatography-tandem mass spectrometry, Water stress, 1.6 Biological sciences, 1.1. Scientific article indexed in Web of Science and/or Scopus database, General
Citation
Kanno, Y, Hanada, A, Chiba, Y, Ichikawa, T, Nakazawa, M, Matsui, M, Koshiba, T, Kamiya, Y & Seo, M 2012, 'Identification of an abscisic acid transporter by functional screening using the receptor complex as a sensor', Proceedings of the National Academy of Sciences of the United States of America, vol. 109, no. 24, pp. 9653-9658. https://doi.org/10.1073/pnas.1203567109