ABA REDUCES RESPIRATION AND SUGAR METABOLISM IN DEVELOPING CARROT (DAUCUS-CAROTA L) EMBRYOIDS

Addition of abscisic acid (ABA) to developing carrot embryoids affects respiration and carbohydrate metabolism. Non-treated embryoids have a high level of respiration expressed per gram protein and consume all most all of their endogenous carbohydrates during the ten day culture period. In contrast, embryoids grown with either 1.9 or 38 mu M ABA, h ave a lowered respiration rate and maintain their carbohydrate content s at 20% of the DW. Embryoids acquire complete desiccation tolerance, when they are treated with 38 mu M ABA, whereas only 65% of the embryo ids survive desiccation with 1.9 mu M ABA. The reduced respiration of the developing embryoids might result in lower free radical levels aft er dehydration, in this way preventing a subsequent viability loss. We suggest that there is a relation between viability loss due to desicc ation and respiration rate, although the latter is not the only factor involved.