Journal Article

A Grape Berry (<i>Vitis vinifera</i> L.) Cation/Proton Antiporter is Associated with Berry Ripening

Mohsen Hanana, Olivier Cagnac, Toshio Yamaguchi, Saïd Hamdi, Abdelwahed Ghorbel and Eduardo Blumwald

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 48, issue 6, pages 804-811
Published in print June 2007 | ISSN: 0032-0781
Published online June 2007 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcm048
A Grape Berry (Vitis vinifera L.) Cation/Proton Antiporter is Associated with Berry Ripening

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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We have cloned and characterized VvNHX1, a gene encoding a vacuolar cation/H+ antiporter from Vitis vinifera cv. Cabernet Sauvignon. VvNHX1 belongs to the vacuolar NHX protein family and showed high similarity to other known vacuolar antiporters. The expression of VvNHX1 partially complements the salt- and hygromycin-sensitive phenotypes of an ena1-4 nhx1 yeast strain. Immunoblots of vacuoles of yeast expressing a VvNHX1, together with the expression of a VvNHX1–GFP (green fluorescent protein) chimera demonstrated that VvNHX1 localized to the vacuoles. VvNHX1 displayed low affinity K+/H+ and Na+/H+ exchange activities (12.8 and 40.2 mM, respectively). The high levels of expression of VvNHX1 during the véraison and post-véraison stages would indicate that the increase in vacuolar K+ accumulation, mediated by VvNHX1, is needed for vacuolar expansion. This process, together with the rapid accumulation of reducing sugars, would drive water uptake to the berry and the concomitant berry size increase, typical of the post-véraison stage of growth.

Keywords: Cation/H+ antiporter; Grape berry — NHX; Vacuole; Véraison; Vitis vinifera

Journal Article.  4907 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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