SUCROSE UPTAKE AND METABOLISM IN A DOUBLE-LAYER SYSTEM FOR MICROPROPAGATION OF ROSA-MULTIFLORA

Uptake and metabolism of sucrose in micropropagated Rosa multi;flora u sing the double layer technique was investigated. In the multiplicatio n as well as the root induction stage, hydrolysis of sucrose in the cu lture medium was observed. A mathematical model was developed to quant ify sucrose hydrolysis and the uptake of sucrose, glucose and fructose , based on the time series for the different sugars in the culture med ium. These data were linked to a study of the sugar metabolism in the microshoots. After 48 h of incubation on C-14-[U]-glucose containing m edium, the incorporated label was mainly detected in the ethanol solub le fraction; within this fraction sucrose was the most important compo und. This indicates a significant re-synthesis of sucrose in the plant material after the uptake of hexose. To assess the extent that differ ent enzymes of sucrose metabolism (invertases, sucrose synthase and su crose-P-synthase) were involved, their activity in different plant par ts (of final stage III microshoots) were assayed. A decreasing gradien t for sucrose metabolising enzymes from the roots toward the leaves ga ve a good indication of how the different tissues depend on sucrose ab sorbed from the medium.