Low source–sink ratio reduces reserve starch in grapevine woody canes and modulates sugar transport and metabolism at transcriptional and enzyme activity levels

• Published in: Planta Vol. 246; no. 3; pp. 525 - 535
• Main Authors: Silva, Angélica, Noronha, Henrique, Dai, Zhanwu, Delrot, Serge, Gerós, Hernâni
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Science + Business Media 01.09.2017; Springer Nature; Springer Berlin Heidelberg; Springer Nature B.V
• Subjects: Agricultural practices; Agriculture; beta-Fructofuranosidase - metabolism; Biomedical and Life Sciences; Carbohydrate Metabolism - physiology; Catalysis; Chips; Chromatography, High Pressure Liquid; Concentration (composition); Cuttings; Ecology; Enzymatic activity; Enzyme activity; Enzymes; Forestry; Fruits; Gene expression; Gene Expression Regulation, Plant - physiology; Genes; Invertase; Leaf removal; Leaves; Life Sciences; Metabolism; Microscopy, Electron, Scanning; Monosaccharide Transport Proteins - metabolism; ORIGINAL ARTICLE; Phenols; Plant Sciences; Plant Stems - metabolism; Plant Stems - physiology; Plant Stems - ultrastructure; Plants (botany); Real-Time Polymerase Chain Reaction; Science & Technology; Stability; Starch; Starch - metabolism; Sucrose; Sugar; Transcription; Viticulture; Vitis - enzymology; Vitis - metabolism; Vitis - physiology; Vitis vinifera; Wine; Wines; Leaf removal; Starch; Leaf–cluster ratio; Viticulture; Vitis vinifera; expression des gènes; leaf removal; vitis vinifera; viticulture; leaf–cluster ratio; starch; traitement des feuilles; saccharose
• ISSN: 0032-0935; 1432-2048; 1432-2048
• DOI: 10.1007/s00425-017-2708-6

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.