Cloning and Expression of a Hexose Transporter Gene Expressed during the Ripening of Grape Berry1

Abstract

The ripening of grape (Vitis vinifera L.) is characterized by massive sugar import into the berries. The events triggering this process and the pathways of assimilate transport are still poorly known. A genomic clone Vvht1 (Vitis vinifera hexose transporter1) and the corresponding cDNA encoding a hexose transporter whose expression is induced during berry ripening have been isolated. Vvht1 is expressed mainly in the berries, with a first peak of expression at anthesis, and a second peak about 5 weeks after véraison (a viniculture term for the inception of ripening). Vvht is strictly conserved between two grape cultivars (Pinot Noir and Ugni-Blanc). The organization of the Vvht1 genomic sequence is homologous to that of the Arabidopsis hexose transporter, but differs strongly from that of the Chlorella kessleri hexose transporter genes. The Vvht1 promoter sequence contains several potential regulating cis elements, including ethylene-, abscisic acid-, and sugar-responsive boxes. Comparison of the Vvht1 promoter with the promoter of grape alcohol dehydrogenase, which is expressed at the same time during ripening, also allowed the identification of a 15-bp consensus sequence, which suggests a possible co-regulation of the expression of these genes. The expression of Vvht1 during ripening indicates that sucrose is at least partially cleaved before uptake into the flesh cells.

A Sugar-Inducible Protein Kinase, VvSK1, Regulates Hexose Transport and Sugar Accumulation in Grapevine Cells

“…The involvement of VvSK1 in the control of sugar compartmentation was further strengthened by the fact that cells overexpressing VvSK1 accumulate twice more Glc and three times more Suc than the control, whereas the starch content remains unaffected. Sugar levels of suspension cells significantly differ from those in berries, where monosaccharide concentrations can reach 1.5 M, whereas Suc is poorly detectable (Fillion et al, 1999;Liu et al, 2006). In this context, the role of VvSK1 on sugar transport and accumulation in grape berries has to be further investigated by altering VvSK1 expression in berries.…”

Involvement of Abscisic Acid in the Coordinated Regulation of a Stress-Inducible Hexose Transporter (VvHT5) and a Cell Wall Invertase in Grapevine in Response to Biotrophic Fungal Infection

“…Genes encoding grapevine vacuolar invertases VvGIN1 and VvGIN2 were previously reported by Davies and Robinson (1996) and, based on the PN40024 genome sequence, are the only two predicted vacuolar invertase sequences in the grapevine genome. The grapevine genome contains 16 putative VvHT gene sequences (Supplemental Table S1) belonging to the STP subfamily of plasma membrane H + -monosaccharide symporters (Johnson et al, 2006;Bü ttner, 2007), but only five of these genes (VvHT1 to -5) have been functionally characterized to date (Fillion et al, 1999;Hayes et al, 2007).…”

Evidence for Apoplasmic Phloem Unloading in Developing Apple Fruit

“…To analyze the expression of monosaccharide transporters, immunoblotting with the antiserum raised against the putative grape hexose transporter VvHT1 (Fillion et al, 1999) was carried out in different subcellular fractions of the fruit flesh, and the protein was further immunolocalized on ultrathin sections of embedded material with this heterologous antiserum. The anti-VvHT1 serum recognized a single polypeptide in the plasma membrane fraction of the fruit flesh, with an apparent molecular mass of approximately 52 kD (Fig.…”

“…A 443-bp cDNA fragment containing the 141-bp 3# end coding and the poly A region of the putative grapevine hexose transporter VvHT1 isolated by one of our laboratories (Fillion et al, 1999) was obtained by PCR amplification. The oligonucleotide primers used for PCR were sense (Cterm): 5#TTG CCT GAA TTC AAA GGC AT3# and antisense (T3) SK plasmid primer.…”