ISHS Acta Horticulturae 640: XXVI International Horticultural Congress: Viticulture - Living with Limitations
GRAPEVINE PHLOEM SAP ANALYSIS: 1-SUCROSE ACIDS, POTASSIUM CONCENTRATIONS, SEASONAL AND DIURNAL PATTERNS |
| Authors: | M. Gholami, B.G. Coombe, S.R. Robinson |
| Abstract:
Sucrose, amino acids and mineral ions were analyzed in phloem exudates collected from three grape cultivars. The sucrose concentration in the phloem exudates from different cultivars was found to be high while glucose and fructose were low. In addition to sucrose, substantial levels of amino acids and potassium were also detected in the exudates. Glutamine was the principal amino acid in the phloem exudates of grapevines followed by glutamic and aspartic acids, and alanine. Omission of EDTA from the buffer solution or girdling of canes either side of the bunch greatly decreased the levels of all these sugars and amino acids in the exudates. These controls together with the observed composition of the collected mineral, suggested that the exudates were predominantly derived from phloem sap entering berries in the laterals. The metabolites exuded from phloem of the fruit bunch stem showed seasonal and diurnal variations. The diurnal pattern of sucrose exudation showed high levels of sucrose exuded at night. Total amino acids and some individual amino acids also showed diurnal variation. | |
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