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- Title
Characterization of Top Leader Elongation in Nordmann Fir (Abies nordmanniana).
- Authors
Martens, Helle Juel; Sørensen, Steen; Burow, Meike; Veierskov, Bjarke
- Abstract
Our understanding of the developmental changes that occur during top leader elongation in gymnosperms lags behind that in angiosperms. We developed a semiquantitative method for determining epidermal cell size, by measuring the Feret diameter after cell wall staining of stem epidermal peels. This method allowed a large number of cells to be measured at various locations in the top leader of the Christmas tree Abies nordmanniana. Further, we have identified the growth rate of individual sections of the top leader, and the relationship between cell length and needle arrangement throughout the top leader. At bud break, all stem units begin to elongate simultaneously, but growth ceases from the base upwards during top leader elongation. Long top leaders were characterized by having up to three times as long cells at the base compared to short top leaders, whereas the cell lengths were similar in the apical region independent of the given plant growth capacity. In the basal sector, the level of auxin was much higher, whereas the levels of cytokinins were lower than in the apical sector, causing the auxin/cytokinin ratio to change from about 3 in the apical sector to more than 20 in the basal part. The Fibonacci number changed in the apical sector due to an increased cell number in the stem units and therefore longer distance between the needles. We conclude that the general growth pattern during top leader elongation in A. nordmanniana is similar to angiosperms but differs at the cellular level.
- Subjects
FIR; PLANT capacity; CHRISTMAS trees; CELL size; CYTOKININS; PLANT growth
- Publication
Journal of Plant Growth Regulation, 2019, Vol 38, Issue 4, p1354
- ISSN
0721-7595
- Publication type
Article
- DOI
10.1007/s00344-019-09938-5