Planta

, Volume 207, Issue 2, pp 235–240

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

  • Simon F. Durdan
  • Robert J. Herbert
  • Dennis Francis
Article

DOI: 10.1007/s004250050478

Cite this article as:
Durdan, S., Herbert, R. & Francis, D. Planta (1998) 207: 235. doi:10.1007/s004250050478

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.

Key words: Cell cycle DNA replication Flowering Pharbitis (flowering) Replicon Silene (flowering) 

Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • Simon F. Durdan
    • 1
  • Robert J. Herbert
    • 1
  • Dennis Francis
    • 2
  1. 1.School of Environmental Sciences and Land Management, University College Worcester, Henwick Grove, Worcester, WR2 6AJ, UKGB
  2. 2.School of Biosciences, PO Box 915, University of Wales, Cardiff, CF1 3TL, UKGB

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