Titre du document / Document title
Activation of latent origins of DNA replication in florally determined shoot meristems of long-day and short-day plants : Silene coeli-rosa and Pharbitis nil
Auteur(s) / Author(s)
DURDAN S. F. (1) ;
HERBERT R. J. (1) ;
FRANCIS D. (2) ;
Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)
(1) School of Environmental Sciences and Land Management, University College Worcester, Henwick Grove, Worcester, WR2 6AJ, ROYAUME-UNI
(2) School of Biosciences, PO Box 915, University of Wales, Cardiff, CF1 3TL, ROYAUME-UNI
Résumé / Abstract
Replicon spacing was measured during the S-phase of the cell cycle in shoot meristems of Silene coeli-rosa L., a long-day (LD) plant, and Pharbitis nil Chois, a short-day (SD) plant to examine the hypothesis that activation of latent origins of DNA replication is a feature of floral determination. Silene coeli-rosa was germinated and grown in SD for 28 d and then exposed to either a florally inductive combination of 7 LD + 2 SD, the last day of which coincides with determination of the sepal and stamen whorls, or was germinated and grown in 37 non-inductive SD. Pharbitis nil was germinated and grown in continuous light (CL) for 5 d and then given either 48 h of inductive darkness followed by 1 d of CL, the last day of which coincides with determination of the sepal, petal and stamen whorls, or given one of two independent non-inductive treatments: 48 h dark interrupted by red light (R) + 1 d of CL, or 8 d of CL. Following these treatments, each batch of plants was exposed to tritiated [methyl-
3H]thymidine for 30, 60, 90 or 120 min. Apical domes were dissected, nuclei lysed and prepared as fibre autoradiographs from which replicon size was recorded. In S. coeli-rosa, replicon size was in the range 10-15 μm in SD (non-inductive) and 0-5 μm in LD (inductive) while in P. nil it was 10-15 μm in the 48 h dark interrupted by R, 5-10 μm in CL (both non-inductive) but was reduced to 0-5 μm in the 48 h dark treatment (inductive). Therefore, the recruitment of additional initiation points for DNA replication occurred in both a LD and a SD plant immediately before the appearance of floral organs. The data are consistent in showing that a shortening of S-phase, which is a characteristic feature of florally determined shoot meristems for both species, is brought about by the activation of latent origins of DNA replication.
Revue / Journal Title
Planta
ISSN
0032-0935
CODEN PLANAB
Source / Source
1998, vol. 207, n
o2, pp. 235-240 (29 ref.)
Langue / Language
Anglais
Editeur / Publisher
Springer, Heidelberg, ALLEMAGNE
(1925)
(Revue)
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Localisation / Location
INIST-CNRS, Cote INIST : 916, 35400007195978.0100
Nº notice refdoc (ud4) : 1610995
