Angélica Silva1, Henrique Noronha2, Zhanwu Dai3, Serge Delrot3, Hernâni Gerós1,4,5. 1. Centro de Investigação e de Tecnologias Agro-ambientais e Biológicas (CITAB), Vila Real, Portugal. 2. Centro de Investigação e de Tecnologias Agro-ambientais e Biológicas (CITAB), Vila Real, Portugal. henriquenoronha@bio.uminho.pt. 3. UMR EGFV, Bordeaux Science Agro, INRA, Université de Bordeaux, Villenave D'Ornon, France. 4. Centre of Molecular and Environmental Biology (CBMA), University of Minho, Braga, Portugal. 5. Centre of Biological Engineering (CEB), University of Minho, Braga, Portugal.
Abstract
MAIN CONCLUSION: Severe leaf removal decreases storage starch and sucrose in grapevine cv. Cabernet Sauvignon fruiting cuttings and modulates the activity of key enzymes and the expression of sugar transporter genes. Leaf removal is an agricultural practice that has been shown to modify vineyard efficiency and grape and wine composition. In this study, we took advantage of the ability to precisely control the number of leaves to fruits in Cabernet Sauvignon fruiting cuttings to study the effect of source-sink ratios (2 (2L), 6 (6L) and 12 (12) leaves per cluster) on starch metabolism and accumulation. Starch concentration was significantly higher in canes from 6L (42.13 ± 1.44 mg g DW-1) and 12L (43.50 ± 2.85 mg g DW-1) than in 2L (22.72 ± 3.10 mg g DW-1) plants. Moreover, carbon limitation promoted a transcriptional adjustment of genes involved in starch metabolism in grapevine woody tissues, including a decrease in the expression of the plastidic glucose-6-phosphate translocator, VvGPT1. Contrarily, the transcript levels of the gene coding the catalytic subunit VvAGPB1 of the VvAGPase complex were higher in canes from 2L plants than in 6L and 12L, which positively correlated with the biochemical activity of this enzyme. Sucrose concentration increased in canes from 2L to 6L and 12L plants, and the amount of total phenolics followed the same trend. Expression studies showed that VvSusy transcripts decreased in canes from 2L to 6L and 12L plants, which correlated with the biochemical activity of insoluble invertase, while the expression of the sugar transporters VvSUC11 and VvSUC12, together with VvSPS1, which codes an enzyme involved in sucrose synthesis, increased. Thus, sucrose seems to control starch accumulation through the adjustment of the cane sink strength.
MAIN CONCLUSION: Severe leaf removal decreases storage starch and sucrose in grapevine cv. Cabernet Sauvignon fruiting cuttings and modulates the activity of key enzymes and the expression of sugar transporter genes. Leaf removal is an agricultural practice that has been shown to modify vineyard efficiency and grape and wine composition. In this study, we took advantage of the ability to precisely control the number of leaves to fruits in Cabernet Sauvignon fruiting cuttings to study the effect of source-sink ratios (2 (2L), 6 (6L) and 12 (12) leaves per cluster) on starch metabolism and accumulation. Starch concentration was significantly higher in canes from 6L (42.13 ± 1.44 mg g DW-1) and 12L (43.50 ± 2.85 mg g DW-1) than in 2L (22.72 ± 3.10 mg g DW-1) plants. Moreover, carbon limitation promoted a transcriptional adjustment of genes involved in starch metabolism in grapevine woody tissues, including a decrease in the expression of the plastidic glucose-6-phosphate translocator, VvGPT1. Contrarily, the transcript levels of the gene coding the catalytic subunit VvAGPB1 of the VvAGPase complex were higher in canes from 2L plants than in 6L and 12L, which positively correlated with the biochemical activity of this enzyme. Sucrose concentration increased in canes from 2L to 6L and 12L plants, and the amount of total phenolics followed the same trend. Expression studies showed that VvSusy transcripts decreased in canes from 2L to 6L and 12L plants, which correlated with the biochemical activity of insoluble invertase, while the expression of the sugar transporters VvSUC11 and VvSUC12, together with VvSPS1, which codes an enzyme involved in sucrose synthesis, increased. Thus, sucrose seems to control starch accumulation through the adjustment of the cane sink strength.
Authors: Corina Fusari; Ana M Demonte; Carlos M Figueroa; Mabel Aleanzi; Alberto A Iglesias Journal: Anal Biochem Date: 2006-02-02 Impact factor: 3.365
Authors: Jane Geisler-Lee; Matt Geisler; Pedro M Coutinho; Bo Segerman; Nobuyuki Nishikubo; Junko Takahashi; Henrik Aspeborg; Soraya Djerbi; Emma Master; Sara Andersson-Gunnerås; Björn Sundberg; Stanislaw Karpinski; Tuula T Teeri; Leszek A Kleczkowski; Bernard Henrissat; Ewa J Mellerowicz Journal: Plant Physiol Date: 2006-01-13 Impact factor: 8.340