Effet d'un traitement par l'acide abscisique sur la division cellulaire, les teneurs en ADN et l'élongation du bourgeon cotylédonaire de plants de pois décapités

Abstract

When applied to pea (Pisum sativum L. var. nain hâtif d'Annonay) cotyledonary bud at the time of decapitation, cis-abscisic acid (ABA) induced a decrease in the mitotic indices of the meristem and subapical regions of the bud, in comparison with decapitated but not ABA treated control plants. ABA treatment delayed the entry of the G0–1 nuclei of the inhibited bud into the S phase and then into mitosis. Whatever the ABA concentration (10−3 to 10−7 M), the overall growth of the bud and the elongation of the cortical cells in its subapical region were not affected during the first 48 h. ABA induced an inhibition of bud elongation, all the more important since it was applied later after decapitation. When applied on a 48-h released bud, ABA induced an inhibition of elongation of the bud, a decrease in its mitotic activity, as well as a concentration of the shoot apex nuclei in the G1 phase of the cell cycle. However, this exogenous ABA treatment could not entirely replace the main axis in maintaining the inhibited state of the bud.