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

作者：Perez Castro Ramon; Kasai Koji; Gainza Cortes Felipe; Ruiz Lara Simon; Casaretto Jose A; Pena Cortes Hugo; Tapia Jaime; Fujiwara Toru; Gonzalez Enrique^*

来源：Plant and Cell Physiology, 2012, 53(2): 485-494.

DOI：10.1093/pcp/pcs001

• BOR
• Boron transporter
• Carmenere
• Grapes
• Parthenocarpic
• Vitis

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.