Experiments on Xylem Regeneration in Stem Wound Responses in Coleus

Abstract

1. Experiments were conducted on xylem regeneration in stem wounds of Coleus blumei Benth. 2. Subsurface cell division and wound-xylem regeneration, without the intervention of a dormant zone, was observed in plants with multiple wounds within the same internode. The possibility of lateral migration of auxin under a bioelectric potential is discussed. 3. Cortical puncture wounds that resulted in the disruption of the phloem of a major vascular bundle also resulted in wound-xylem formation by redifferentiation of cortical parenchyma cells. The disruption of the xylem of a major vascular bundle by a pith puncture wound was unsuccessful in inducing wound-xylem regeneration by pith parenchyma cells. 4. Wound-xylem regeneration in defoliated apical shoots was observed approximately 12-14 days following wounding. The wound xylem thus formed appeared in several discrete masses and not in definite contiguous strands. 5. When the plant was decapitated directly above the wound 24 hours after wounding, no wound-xyle...