CHANGES IN THE SUGAR CONTENT IN STEM APICES OF THE SHORT-DAY PLANT PERILLA-NANKINENSIS AT FLORAL TRANSITION

Changes in sugar content were examined in developing stem apices and l eaf primordia of the short-day plant Perilla nankinensis (Lour.) Decne . in the course of floral transition induced by an increasing number o f short days. Under a light microscope, the structural organization of stem apices was compared at the following developmental stages. veget ative development (plants grown under long-day, noninductive condition s), the evocation of flowering (plants induced to flower by one to eig ht short days), and reproductive development (plants induced to flower by 9 to 25 short days). Two peaks of glucose content were observed: a t the beginning of evocation (after photoperiodic induction by six sho rt days) and at the beginning of reproductive apex development. The pe aks of glucose content in the leaf primordia were shifted relative to those of the apices and occurred at 8 and 12 short days. Sugars are po stulated to be involved in the transduction of signals that contribute to the coordination of cell differentiation after the new genetic pro gram of plant reproductive development is expressed.