Sucrose metabolism in sugar cane grown under varying climatic conditions: Synthesis and storage of sucrose in relation to the activities of sucrose synthase, sucrose-phosphate synthase and invertase

Abstract

The contents of sucrose and hexoses in relation to the activities of sucrose synthase, sucrose-phosphate synthase and soluble invertase in leaf blade and of soluble and wall-bound invertase in stem tissues of sugar cane growing under naturally varying weather conditions were determined. In leaf blades, sucrose synthase, sucrose-phosphate synthase and soluble invertase were most active at tillering. Sucrose synthase was relatively more active than sucrose-phosphate synthase throughout the growth of the cane. In stem tissues the activity of soluble acid invertase was highest at the stem elongation stage and then declined, whereas the activities of soluble neutral invertase and wall-bound acid invertase increased with age. With the ageing of the cane, sucrose accumulation in the stem gradually increased with a concomitant fall in hexose content. A narrow ratio ofsucrose in the basal to top portion of the cane relates to maturity of the cane. On feeding uniformly labelled sucrose and hexoses to storage tissue for 4 hr. ca 85–90 % of the 14C in intracellular sugars was present in sucrose. Synthesis of sucrose from glucose in leaf disks was stimulated by Mg 2+ and Mn 2+.