Summary
The ability of a developing cottonwood (Populus deltoides Bartr.) leaf to export 14C-labeled assimilates begins at the lamina tip and progresses basipetally with increasing LPI. This progression indicates that portions of leaves function quasi-independently in their ability to export 14C-photosynthate. Although most of the exported radioactivity was recovered in the petiole as water-80% alcohol-soluble compounds, there was also substantial incorporation into the chloroform and insoluble fractions. This observation indicates that assimilates translocated from the lamina are used in structural development of the petiole. Freeze substitution and epoxy embedding were used to prepare microautoradiographs for localization of water-soluble compounds. Radioactivity was found in all cell types within specific subsidiary bundles of the petiole. However, radioactive assimilates appeared to move from the translocation pathway in the phloem toward active sinks in the walls of the expanding metaxylem cells. Translocation in the mature xylem vessels was not observed.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Biddulph, O., Cory, R.: Translocation of C14 metabolites in the phloem of the bean plant. Plant Physiol. 40, 119–129 (1965)
Bieleski, R.L.: Sites of accumulation in excised phloem and vascular tissues. Plant Physiol. 41, 455–466 (1966)
Canny, M.J.: Phloem translocation London: Cambridge Univ. Press 1973
Crafts, A.A., Crisp, C.E.: Phloem transport in plants. San Francisco: Freeman 1971
Dickmann, D.I.: Photosynthesis and respiration by developing leaves of cottonwood (Populus deltoides Bartr.) Bot. Gaz 132, 253–259 (1971)
Dickson, R.E.: Source-sink relationships in 14C-labelling of structural carbohydrates in cottonwood. (Abstr.) Plant Physiol. 53, Suppl., 68 (1974)
Dickson, R.E., Larson, P.R.: Incorporation of 14C-photosynthate into major chemical fractions of source and sink leaves of cottonwood. Plant Physiol. 56, 185–193 (1975)
Eschrich, W., Fritz, E.: Microautoradiography of water soluble organic compounds. In: Microautoradiography and electron probe analysis pp. 99–122, Ed.: Luttge, U. Berlin-Heidelberg-New York: Springer 1972
Fellows, R.J., Geiger, D.R.: Structural and physiological changes in sugar beet leaves during sink to source conversion. Plant Physiol. 54, 877–885 (1974)
Fisher, D.B.: Artifacts in the embedment of water soluble compounds for light microscopy. Plant Physiol. 49, 161–165 (1972)
Fisher, D.B., Housley, T.L.: The retention of water soluble compounds during freeze substitution and microautoradiography. Plant Physiol. 49, 166–171 (1972)
Fritz, E.: Microautoradiographic investigations in bidirectional translocation in the phloem of Vicia faba. Planta (Berl.) 112, 169–179 (1973)
Hoddinott, J., Gorham, P.R.: Translocation of 14C-labelled assimilates in petioles and phloem loops of Heracleum lanatum. Canad. J. Bot. 52, 349–353 (1974)
Howard, R.A.: The stem-node-leaf continuum of the Dicotyledoneae. J. Arnold Arb. 55, 125–170 (1974)
Isebrands, J.G., Larson, P.R.: Anatomical changes during leaf ontogeny in Populus deltoides. Amer. J. Bot. 60, 199–208 (1973)
Jones, H., Martin, R.V., Porter, H.K.: Translocation of 14carbon in tobacco following assimilation of 14carbon dioxide by a single leaf. Ann. Bot 23, 494–508 (1959)
Kipps, A.E., Boulter, D.: Origins of the amino acids in pods and seeds of Vicia faba L. New Phytol. 73, 675–684 (1974)
Köcher, H., Leonard, O.A.: Translocation and metabolic conversion of 14C-labelled assimilates in detached and attached leaves of Phaseolus vulgaris L. in different phases of leaf expansion. Plant Physiol. 47, 212–216 (1971)
Larson, P.R.: Organization and development of the primary vascular system in Populus deltoides according to phyllotaxy. Amer. J. Bot. (in press)
Larson, P.R., Dickson, R.E.: Distribution of imported 14C in developing leaves of eastern cottonwood according to phyllotaxy. Planta (Berl.), 111, 95–112 (1973)
Larson, P.R., Isebrands, J.G.: The plastochron index as applied to developmental studies of cottonwood. Canad. J. For. Res. 1, 1–11 (1971)
Larson, P.R., Isebrands, J.G., Dickson, R.E.: Fixation patterns of 14C within developing leaves of eastern cottonwood. Planta 107, (Berl.) 301–314 (1972)
Moore, K.G., Illsley, A., Lovell, P.H.: Effects of sucrose on petiolar carbohydrate accumulation and photosynthesis in excised Sinapis cotyledons. J. exp. Bot 25, 887–898 (1974)
Mortimer, D.C.: Translocation of the products of photosyntheis in sugar beet petioles. Canad. J. Bot. 43, 269–280 (1965)
Penny, P., Nelson, C.D.: Movement within leaves and plants of 14C applied as 14CO2. Canad. J. Bot. 48, 1033–1037 (1970)
Schmitz, K.: Untersuchungen zur funktionellen Anatomie des Leitgewebesystems im Blatt von Pelargonium zonale. Planta (Berl.) 92, 208–221 (1970)
Spurr, A.R.: A low-viscosity epoxy resin embedding medium for electron microscopy. J. Ultrastruct. Res. 26, 31–43 (1969)
Trip, P., Gorham, P.R.: Translocation of radioactive sugars in the vascular tissues of soybean plants. Canad. J. Bot. 46, 1129–1133 (1968)
Wardlaw, I.F.: The control and pattern of movement of carbohydrates in plants. Bot. Rev. 34, 79–105 (1968)
Wardlaw, I.F.: Phloem transport: Physical, chemical, or impossible. Ann. Rev. Plant Physiol. 25, 515–539 (1974)
Wardlaw, I.F., Mortimer, D.C.: Carbohydrate movement in pea plants in relation to axillary bud growth and vascular development. Canad. J. Bot. 48, 229–237 (1970)
Watari, S.: Anatomical studies on the vascular system in the petioles of some species of acer with notes on external morphological features. J. Fac. Sci. Univ. Tokyo, Sec. III, 5, 1–73 (1936)
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Isebrands, J.G., Dickson, R.E. & Larson, P.R. Translocation and incorporation of 14C into the petiole from different regions within developing cottonwood leaves. Planta 128, 185–193 (1976). https://doi.org/10.1007/BF00393227
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00393227