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J. WARREN WILSON, R. I. GRANGE, Regeneration of Tissues in Wounded Stems: A Quantitative Study, Annals of Botany, Volume 53, Issue 4, April 1984, Pages 515–525, https://doi.org/10.1093/oxfordjournals.aob.a086715
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Abstract
When a dicotyledonous stem is wounded by longitudinally splitting a young internode into halves, cells near the cut surface proliferate to form a callus within which vascular tissues differentiate and tend to restore a vascular cylinder in each half. Three phases of regeneration after wounding were identified and quantified in stems of three Solanaceous species. (1) In an initial ‘lag’ phase, lasting about 2 d, neither cell division nor enlargement were detected, but mitotic figures were observed within about 300 μm of the cut surface. (2) Throughout a second, ‘division’ phase, from about days 2–10, cell division and enlargement occurred. Both were initiated mainly in the two cell layers nearest the surface. A mass of callus formed, with new cell walls mostly parallel to the surface. Cell enlargement lagged behind cell division for the first few days, so that mean radial cell diameter decreased until day 6, thereafter remaining almost constant at 30–40 μm. Towards the end of this phase, mitoses ceased within the callus except in the positions of the future vascular and cork cambia, where radial cell diameter fell towards a constant 15–20 μm. (3) During a third, ‘differentiation’ phase, cell division was restricted to the cambial zones, and derivatives differentiated into cork, phloem or xylem according to position. The rate of increase in cell number per transect was 1.5–2.0 cells d−1, of which more than half was xylem.
