Cellular Kinetics of Compression Wood Formation in Slash Pine
Keywords:Southern pine, compression wood, cellular kinetics, tracheid differentiation
AbstractThe kinetics of auxin-induced compression wood formation in slash pine (Pinus elliottii Engelm.) seedlings were investigated with regard to rate and duration of cambial cell division, radial enlargement, and secondary wall formation. Exogenous lateral application of auxin (indole acetic acid) in lanolin paste to the basal portion of the seedling stems markedly increased the rate of cambial cell division and radial enlargement with a nearly proportionate decrease in the duration of both stages. The auxin application had little effect on the rate of secondary wall formation of differentiating tracheids but significantly increased the duration of this stage, resulting in a large increase in tracheid wall thickness. Untreated control seedlings exhibited no evidence of changes in cellular kinetics during the treatment period. Results indicate that the increased wall thickness of compression wood tracheids in slash pine results from an extended duration of secondary wall deposition rather than an increased rate of deposition as previously thought.
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