caa a22 4500 47710102X CHVBK 20180405111541.0 cr unu---uuuuu 170330e19960401xx s 000 0 eng 10.1007/BF00262647 doi (NATIONALLICENCE)springer-10.1007/BF00262647 The development of phloem anastomoses between vascular bundles and their role in xylem regeneration after wounding in Cucurbita and Dahlia [Elektronische Daten] [Roni Aloni, John Barnett] The differentiation of phloem anastomoses linking the longitudinal vascular bundles has been studied in stem internodes of Cucurbita maxima Duchesne, C. pepo L. and Dahlia pinnata Cav. These anastomoses comprise naturally occurring regenerative sieve tubes which redifferentiate from interfascicular parenchyma cells in the young internodes. In all three species, severing a vascular bundle in a young internode resulted in regeneration of xylem to form a curved by-pass immediately around the wound. The numerous phloem anastomoses in these young internodes were not involved in this process, the regenerated vessels originating from interfascicular parenchyma alone. Conversely, in mature internodes of Dahlia, the regenerated vessels originated from initials of the interfascicular cambia, and their phloem anastomoses did not influence the pattern of xylogenesis. On the other hand, in old internodes of Cucurbita, in which an interfascicular cambium was not yet developed, the parenchyma cells between the bundles had lost the ability to redifferentiate into vessel elements, and instead, regenerated vessels were produced in the phloem anastomoses. Thus, the wounded region of the vascular bundle was not bypassed via the shortest, curved pathway, but by more circuitous routes further away from the wound. Some of the regenerated vessels produced in the phloem anastomoses were extremely wide, and presumably efficient conductors of water. It is proposed that the dense network of phloem anastomoses developed during evolution as a mechanism of adaptation to possible damage in mature internodes by providing flexible alternative pathways for efficient xylem regeneration in plants with limited or no interfascicular cambium. Springer-Verlag, 1996 Cucurbita nationallicence Dahlia nationallicence Phloem (anastomoses, development, function) nationallicence Xylem (regeneration, efficiency) nationallicence Aloni Roni Department of Botany, George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978, Tel Aviv, Israel aut Barnett John School of Plant Sciences, The University of Reading, Whiteknights, PO Box 221, RG6 6AS, Reading, UK aut Planta Springer-Verlag 198/4(1996-04-01), 595-603 0032-0935 198:4<595 1996 198 425 https://doi.org/10.1007/BF00262647 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00262647 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Aloni Roni Department of Botany, George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978, Tel Aviv, Israel aut NATIONALLICENCE 700 1- Barnett John School of Plant Sciences, The University of Reading, Whiteknights, PO Box 221, RG6 6AS, Reading, UK aut NATIONALLICENCE 773 0- Planta Springer-Verlag 198/4(1996-04-01), 595-603 0032-0935 198:4<595 1996 198 425 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer