Tissue Culture of Secondary Xylem Parenchyma of Four Species of Southern Pines

Robert M. Allen, Evelyn N. Hiatt

Abstract


Callus was grown from increment core explants of longleaf pine (Pinus palustris Mill.), slash pine (P. elliottii Engelm.), loblolly pine (P. taeda L.), and shortleaf pine (P. echinata Mill.) trees that had 30-45 annual rings of sapwood. Callus emanated from vertical and horizontal resin canals and uniserate rays. It originated from epithelial cells and longitudinal and ray parenchyma cells. There was relatively little difference in the amount of callus produced from the outer to inner sapwood of longleaf and slash pines compared to the reduction that occurred in loblolly and shortleaf pines. Production was generally lower in the transition zone, especially in loblolly and shortleaf pines, and virtually nonexistent in the heartwood. Several current theories of heartwood formation are discussed in light of the results.

Keywords


Tissue culture;resin canals;transition zone;sapwood;rays;xylem parenchyma;heartwood formation;<i>Pinus palustris</i>;<i>P. elliottii</i>;<i>P. taeda</i>;<i>P. echinata</i>

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