Abstract
It has been proposed that peg formation in the vascular transition region (TR zone) between the hypocotyl and the root in Cucurbitaceae seedlings is a gravimorphogenetic phenomenon. Initiation of the peg became visible 36 h after imbibition when cucumber (Cucumis sativus L. cv. Burpee Hybrid II) seeds were germinated in a horizontal position at 24°C in the dark. Simultaneously, sedimented amyloplasts (putative statoliths) were apparent in the sheath cells surrounding the vascular strands, and in the cortical cells immediately adjacent to them, in the TR zone. In contrast, the other cortical cells, some of which were destined to develop into the peg, contained amyloplasts which were not sedimented. These results suggest that the graviperception mechanism for peg formation may be like that of statoliths in shoot gravitropism. By 48 h following imbibition, the cells of the TR zone still had sedimented amyloplasts but had lost their sensitivity to gravity, possibly because of their maturation.
Abbreviations
- TR zone:
-
vascular transition zone between hypocotyl and root
References
Crocker, W., Knight, L.I., Robert, E. (1910) The peg of the Cucurbitaceae. Bot. Gaz.L (5), 321–339
Darwin, C. (1880) The power of movement in plants. John Murray, London
Holroyd, R. (1924) Morphology and physiology of the axis in Cucurbitaceae. Bot. Gaz.LXXVIII (1), 1–45
MacDonald, I.R., Gordon, D.C., Hart, J.W., Maher, E.P. (1983) The positive hook: the role of gravity in the formation and opening of the apical hook. Planta158, 76–81
Sack, F.D. (1991) Plant gravity sensing. Internat. Rev. Cytol.127, 193–252
Spurr, A.R. (1969) A low-viscosity resin embedding medium for electron microscopy. J. Ultrastruct. Res.26, 31–34
Takahashi, H., Suge, H. (1988) Involvement of ethylene in gravity-regulated peg development in cucumber seedling. Plant Cell Physiol.29, 313–320
Volkmann, D., Sievers, A. (1979) Graviperception in multicellular organs. In: Encyclopedia of plant physiology, N.S., vol. 7: Physiology of movements, pp. 573–600, Haupt, W., Feinleib, M.E., eds. Springer, Berlin Heidelberg New York
Witztum, A., Gersani, M. (1975) The role of polar movement of IAA in the development of the peg inCucumis sativus L. Bot. Gaz.136, 5–16
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Takahashi, H., Scott, T.K. Gravity-regulated formation of the peg in developing cucumber seedlings. Planta 193, 580–584 (1994). https://doi.org/10.1007/BF02411565
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DOI: https://doi.org/10.1007/BF02411565