Seasonal dynamics of biomass, inulin, and water-soluble sugars in roots of Cynara cardunculus L.

Abstract

Cynara cardunculus accumulates inulin in large amounts in roots. Some representative types of cardoons and globe artichoke were genetically screened to select genotypes suitable for total sugar and inulin production in the Mediterranean environment. Seasonal dynamics of biomass, inulin, and water-soluble carbohydrate (W.S.C.) in roots of three taxa of C. cardunculus L. were studied for 2 years, in order to investigate a possible relationship between the physiological state of the plant and the distribution of carbohydrates in roots. Globe artichoke, cultivated cardoon, and wild cardoon were grown in Sicily. Whole biomass was collected monthly. Dry matter partitioning and characterization of root sugars, performed by high-performance anion exchange chromatography (HPAEC), were studied for each. Changes in W.S.C. well correlated with the conditions of growth. In particular, W.S.C. content increased when the plants used their root reserves to overcome cold stress in winter and during formation of stalks and capitula. Maximum inulin content with high degree of polymerization was recorded before the beginning of flower formation. The cardoons and globe artichoke differed in their inulin patterns. Storing fructans in underground organs could be interpreted as an adaptive strategy of C. cardunculus to overcome unfavourable conditions in the Mediterranean region. The three taxa showed different patterns of biomass accumulation and partitioning, reflected in accumulation of inulin and/or its breakdown in roots.