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Photoperiod and gibberellic acid – control of the cell cycle in the meristem of Silene armeria and its effects on flowering
Author(s) -
BesnardWibaut Christiane,
Cochet Thierry,
Noin Michèle
Publication year - 1989
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1989.tb05653.x
Subject(s) - meristem , biology , gibberellic acid , mitosis , botany , photoperiodism , silene , cell division , shoot , microbiology and biotechnology , cell , germination , biochemistry
Plants of Silene armeria L., strain S 2.1 , a quantitative long‐day (LD) species which is known to react to GA 3 by flowering after attaining, the‘intermediate stage’, were induced by two LD or by two GA 3 applications. Changes in the mitotic index and DNA content (microdensitometric estimation) of cells in the axial zone, lateral zone and rib meristem of the shoot apex were observed during the first 48 h of each treatment. Similar mitotic activation occurred in response to LD or GA 3 after a 6‐8 h lag period. This was preceded by a decrease in the proportion of nuclei with a 2C DNA content, indicating that in this species the control point for the shortening of the cell cycle was essentially in G 1 . A second mitotic peak was observed 16 h later in photoinduced meristems, resulting in more pronounced cellular synchronization. These further events were not seen in GA 3 ‐treated plants where only the meristematic activity was slightly, but reproducibly higher than in the control. Thus, two successive synchronizations of cell division are a typical feature of LD induction. The data are discussed with regard to the competence of shoot apical cells to be reactivated. The essential changes for the transition to flowering depend on these differential patterns of cell reactivation.