VvBOR1, the Grapevine Ortholog of AtBOR1, Encodes an Efflux Boron Transporter That is Differentially Expressed Throughout Reproductive Development of Vitis vinifera L

• Published in: Plant and cell physiology 2012-02, Vol.53 (2), p.485-494
• Main Authors: Pérez-Castro, Ramón, Kasai, Koji, Gainza-Cortés, Felipe, Ruiz-Lara, Simón, Casaretto, José A., Peña-Cortés, Hugo, Tapia, Jaime, Fujiwara, Toru, González, Enrique
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Antiporters - genetics; Antiporters - metabolism; Arabidopsis - genetics; Arabidopsis - metabolism; Boron - metabolism; Flowers - metabolism; Fruit - metabolism; Gene Expression Regulation, Plant; Genetic Complementation Test; Green Fluorescent Proteins - metabolism; Molecular Sequence Data; Phylogeny; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Roots - cytology; Plant Roots - metabolism; Plants, Genetically Modified - genetics; Plants, Genetically Modified - metabolism; Sequence Alignment; Vitis - genetics; Vitis - metabolism
• ISSN: 0032-0781; 1471-9053
• DOI: 10.1093/pcp/pcs001

Boron (B) is an essential micronutrient for normal development of roots, shoots and reproductive tissues in plants. Due to its role in the structure of rhamnogalacturonan II, a polysaccharide required for pollen tube growth, B deficiency has been associated with the occurrence of parthenocarpic seedless grapes in some varieties of Vitis vinifera L. Despite that, it is unclear how B is mobilized and accumulated in reproductive tissues. Here we describe the characterization of an efflux B transporter, VvBOR1, homolog to AtBOR1, which is involved in B xylem loading in Arabidopsis thaliana roots. VvBOR1-green fluorescent protein (GFP) fusion protein expressed in A. thaliana localizes in the proximal plasma membrane domain in root pericycle cells, and VvBOR1 overexpression restores the wild-type phenotype in A. thaliana bor1-3 mutant plants exposed to B deficiency. Complementation of a mutant yeast strain indicates that VvBOR1 corresponds to a B efflux transporter. Transcriptional analyses during grapevine reproductive development show that the VvBOR1 gene is preferentially expressed in flowers at anthesis and a direct correlation between the expression pattern and B content in grapes was established, suggesting the involvement of this transporter in B accumulation in grapevine berries.