A grapevine Shaker inward K(+) channel activated by the calcineurin B-like calcium sensor 1-protein kinase CIPK23 network is expressed in grape berries under drought stress conditions.
Grapevine (Vitis vinifera), the genome sequence of which has recently been reported, is considered as a model species to study fleshy fruit development and acid fruit physiology. Grape berry acidity is quantitatively and qualitatively affected upon increased K(+) accumulation, resulting in deleterious effects on fruit (and wine) quality. Aiming at identifying molecular determinants of K(+) transport in grapevine, we have identified a K(+) channel, named VvK1.1, from the Shaker family. In silico analyses indicated that VvK1.1 is the grapevine counterpart of the Arabidopsis AKT1 channel, known to dominate the plasma membrane inward conductance to K(+) in root periphery cells, and to play a major role in K(+) uptake from the soil solution. VvK1.1 shares common functional properties with AKT1, such as inward rectification (resulting from voltage sensitivity) or regulation by calcineurin B-like (CBL)-interacting protein kinase (CIPK) and Ca(2+)-sensing CBL partners (shown upon heterologous expression in Xenopus oocytes). It also displays distinctive features such as activation at much more negative membrane voltages or expression strongly sensitive to drought stress and ABA (upregulation in aerial parts, downregulation in roots). In roots, VvK1.1 is mainly expressed in cortical cells, like AKT1. In aerial parts, VvK1.1 transcripts were detected in most organs, with expression levels being the highest in the berries. VvK1.1 expression in the berry is localized in the phloem vasculature and pip teguments, and displays strong upregulation upon drought stress, by about 10-fold.VvK1.1 could thus play a major role in K(+) loading into berry tissues, especially upon drought stress.
Cuéllar
Teresa
T
UMR1083, Sciences pour l'OEnologie, INRA, 2 Place Viala, 34060 Montpellier Cedex 1, France.
Pascaud
François
F
Verdeil
Jean-Luc
JL
Torregrosa
Laurent
L
Adam-Blondon
Anne-Françoise
AF
Thibaud
Jean-Baptiste
JB
Sentenac
Hervé
H
Gaillard
Isabelle
I
D000040:Abscisic Acid / Q000494:pharmacology; D029681:Arabidopsis Proteins / Q000145:classification / Q000235:genetics / Q000502:physiology*; D019295:Computational Biology; D055864:Droughts; D005638:Fruit / Q000187:drug effects / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000235:genetics; D018745:Genome, Plant / Q000235:genetics; D017403:In Situ Hybridization; D010802:Phylogeny; D035261:Plant Components, Aerial / Q000187:drug effects / Q000235:genetics; D010940:Plant Proteins / Q000145:classification / Q000235:genetics / Q000502:physiology*; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics; D016133:Polymerase Chain Reaction; D015221:Potassium Channels / Q000145:classification / Q000235:genetics / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000502:physiology*; D051637:Shaker Superfamily of Potassium Channels / Q000145:classification / Q000235:genetics / Q000502:physiology*; D012965:Sodium Chloride / Q000494:pharmacology; D027843:Vitis / Q000187:drug effects / Q000235:genetics*
D029681:Arabidopsis Proteins; D010940:Plant Proteins; D015221:Potassium Channels; D051637:Shaker Superfamily of Potassium Channels; C074500:AKT1 protein, Arabidopsis; D012965:Sodium Chloride; D000040:Abscisic Acid; C514581:CIPK23 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases