APPLICATION OF A SYNCHRONOUS DEVELOPMENT AND TUBERIZATION MODEL IN POTATO CULTIVATED IN-VITRO - EVOLUTION OF ENZYMATIC-ACTIVITIES

In this study was used a model of synchronous development and tuberiza tion, obtained in vitro from uninodal stem fragments of potato, withou t adding any exogenous growth regulator. Upper and basal parts of the stems were sampled at different times and analysed for their soluble p rotein content and for their invertase and sucrose synthase activities . Invertase activity, used as an indicator of the metabolic activity, increased dramatically in the upper part of the stems of plants induce d by short days, particularly with a thermoperiod. This high activity could point out an increase of the sugar metabolism which was associat ed to a preinducting step in the plants. The sucrose synthase activity presents a peak at the tuber level during they are swelling.