INULIN AND WATER-SOLUBLE-SUGARS VARIATIONS IN CYNARA ROOTS DURING THE BIOLOGICAL CYCLE
Inulin-type fructan is a fructose polymer that has the 1,2-ß- fructosyl-fructose linkage. Thanks to its characteristics this fructan can be used for food and non-food applications. In plants inulin serves as reserve carbohydrates, stored in specialized organs, used during regrowth after defoliation and for sprouting in the spring. A different role may be involved in the protection of plants during drought, salt or cold stress. In recent works it was demonstrated inulin, with very high degree of polymerization (over 100), is accumulated in Cynara cardunculus roots. However no physiological stages or carbohydrates content has been determined for optimum harvest time. This work was conducted to quantify changes in carbohydrates content and composition in roots during growth. To reach the aim, during 2001-03 growth seasons, at Catania, in an experimental design with three replications one globe artichoke, one cultivated cardoon and one wild cardoon were grown. During the biological cycle eighteen harvests of three plants, for each genotype and replication, were carried out. Corresponding to each sampling in laboratory, inulin, glucose, fructose and sucrose were determined by HPAEC-PAD (Dionex AI, 500). Water soluble sugar (W.S.C.) were obtained summing glucose, fructose and sucrose. In both the years, the W.S.C. content significantly varied during the growth season. Its trend appeared as a strict correlation with the exigencies of the plant, in particular it increased when the plant used the root energy substances to prevent drought stress in winter time and during the stalk and capitula formation. Inulin content resulted maximised before the beginning of the flower formation, a deeply decreasing followed due to the capitulum growth and the grain ripening.
Melilli, M.G. and Raccuia, S.A. (2007). INULIN AND WATER-SOLUBLE-SUGARS VARIATIONS IN CYNARA ROOTS DURING THE BIOLOGICAL CYCLE. Acta Hortic. 730, 475-481
fructan mobilization, plant growth, glucose, fructose, sucrose