Profiles of enzymes of sucrose metabolism in the leaves of chicory ( Cichorium intybus) during development

Abstract

The activity of sucrose phosphate synthase (SPS) was evenly distributed between the lamina and petiole at all stages of development of Cichorium intybus. As compared to sucrose synthase (SS), the activitie ofSPS in lamina and petiole at both the early (February) and mid-stages (April) of growth were higher . Activities of these enzymes in the lamina and petiole at the mid-stage of development were 3–10 times higher as compared to the early and late (July) stages and coincidedwith the maximum rate of fructan synthesis and dry weight accumulation in roots (sink). The supply of photosynthates to the roots, as revealed by 14CO 2 fixation and its transportation at this stage, was much more when compared to that at late stage. It appeared that at mid-development leaves made use of enhanced activity of SS in addition to SPS activity for meeting the photosynthate requirement of the sink region. Acid invertase remained the major form of invertase during growth. At the early and mid-stages, petioles showed two acid invertase whereas lamina, in addition to two acid invertases, contained an additional low molecular weight alkaline invertase at the late stage. Leaves of the erect stem at the time of flowering contained only one form of acid invertase.