Summary
Sieve-tube exudate which appears on cut surfaces of stems of Cucurbita maxima as distinct droplets has been depicted in electron micrographs of longitudinal sections of the phloem. The exudate, which was produced from mature sieve tubes only, contained filaments of P-protein, but no mitochondria or vesicles of endoplasmic reticulum. The water-soluble part of the exudate contained at least 12 proteins, as shown by disc-electrophoresis. Enzymic activity was found for peroxidases, acid phosphatases, and aldolases. Color tests and assays for other enzymes, including ATPase, fructokinase, several dehydrogenases, and UDP-glucose: D-fructose-2-glucosyl transferase, gave negative results. With repeated cutting of a stem, the protein content of the exudate increased, while the amount of exudate decreased.
Similar content being viewed by others
References
Bieleski, R. L.: Phosphorus compounds in translocating phloem. Plant Physiol. 44, 497–502 (1969).
Boehringer, C. F. & Soehne: Biochemica Katalog. Mannheim 1967.
Braun, H. J., Sauter, J. J.: Phosphatase-Aktivität in den Siebzellen der Koniferennadeln. Naturwissenschaften 51, 170 (1964a).
——: Phosphatase-Lokalisation in Phloembeckenzellen und Siebröhren der Dioscoreaceae und ihre mögliche Bedeutung für den aktiven Assimilattransport. Planta (Berl.) 60, 543–557 (1964b).
Bücher, T., Pfleiderer, G.: Pyruvate kinase from muscle. In: Colowick, S. P., and Kaplan, N. O., Methods in enzymology, vol. I, 435–440. New York: Acad. Press. 1955.
Czaninski, Y., Catesson, A. M.: Localisation ultrastructurale d'activités peroxydasiques dans les tissus conducteurs végétaux au cours du cycle annuel. J. Microscopie 8, 875–888 (1969).
Esau, K.: The phloem. In: Zimmermann, W., Ozenda, P., Wulff, H. D.: Handbuch der Pflanzenanatomie, vol. 5, pt. 2. Berlin-Stuttgart: Borntraeger 1969.
—, Cronshaw, J.: Tubular components in cells of healthy and tobacco mosaic virus-infected Nicotiana. Virology 33, 26–35 (1967).
Eschrich, W.: Untersuchungen über den Ab- und Aufbau der Callose. Z. Bot. 49, 153–218 (1961).
—: Der Phloemsaft von Cucurbita ficifolia. Planta (Berl.) 60, 216–224 (1963).
Figier, J.: Localisation infrastructurale de la phosphomonoestérase acide dans la stipule de Vicia faba L. au niveau du nectaire. Planta (Berl.) 83, 60–79 (1968).
Kennecke, M.: Enzymatische Zusammensetzung von Siebröhrensäften. Doct. diss. Techn. Univ. Darmstadt 1970.
Kluge, J., Ziegler, H.: Der ATP-Gehalt der Siebröhrensäfte von Laubbäumen. Planta (Berl.) 61, 167–177 (1964).
Kursanov, A. L., Sokolova, S. V., Turkina, M. V.: Hexokinase in conducting tissues of sugar-beet and its possible connection with transport of sugars through cell membranes. J. exp. Bot. 21, 30–39 (1970).
Lester, H. H., Evert, R. F.: Acid phosphatase activity in sieve-tube members of Tilia americana. Planta (Berl.) 65, 180–185 (1965).
Lindberg, O., Ernster, L.: Determination of organic phosphorus compounds by phosphate analysis. In: Glick, D., Methods of biochemical analysis, vol. III, p. 1–22, New York: Interscience 1956.
Lowry, O. H., Rosenbrough, N. J., Farr, A. L., Randall, R. J.: Protein measurement with the Folin phenol reagent. J. biol. Chem. 193, 265–275 (1951).
Pearse, A. G. E.: Histochemistry, theoretical, and applied. Boston: Little, Brown 1960.
Peel, A. J., Weatherley, P. E.: Composition of sieve-tube sap. Nature (Lond.) 184, 1955–1956 (1959).
Pontis, H. G., Leloir, L. F.: Measurement of UDP-enzyme systems. In: Glick, D., Methods of biochemical analysis, vol. X, p. 107–136. New York: Interscience 1962.
Potter, V. R.: The homogenate technique. In: Umbreit, W. W., Burris, R. H., and Stauffer, J. F., Manometric techniques, 4 edn., p. 159–176. Minneapolis: Burgess 1964.
Raciborski, M.: Ein Inhaltskörper des Leptoms. Ber. dtsch. bot. Ges. 16, 52–63 (1998a).
—: Weitere Mitteilungen über das Leptomin. Ber. dtsch. bot. Ges. 16, 119–123 (1898b).
Shaw, C. R., Koen, A. L.: Starch gel electrophoresis of enzymes. In: Smith, I., Chromatographic and electrophoretic techniques, vol. II, p. 325–364. Bath, G. B.: Heinemann 1968.
—, Prasad, R.: Starch gel electrophoresis of enzymes—a compilation of recipes. Biochem. Genetics 4, 297–320 (1970).
Ulbrich, M.: Eigenschaften und Lokalisation von Phosphatase in Nektarien- und Phloemgewebe. Dissert. (diploma), Techn. Univ. Darmstadt 1969.
Wanner, H.: Enzyme der Glycolyse im Phloemsaft. Ber. schweiz. bot. Ges. 63, 201–212 (1953).
Yen, L. F., Shih, T. C.: Presence of a contractile protein in higher plants. Acta biochim. biophys. Sinica 3, 490–496 (1963).
Ziegler, H., Huber, F.: Phospataseaktivität in den „Straßburger-Zellen” der Koniferennadeln. Naturwissenschaften 47, 305 (1960).
Author information
Authors and Affiliations
Additional information
Supported by Deutsche Forschungsgemeinschaft and Stiftung Volkswagenwerk. During part of this investigation the senior author held a U.S. National Science Foundation Senior Foreign Scientist Fellowship at the University of Wisconsin.
Rights and permissions
About this article
Cite this article
Eschrich, W., Evert, R.F. & Heyser, W. Proteins of the sieve-tube exudate of Cucurbita maxima . Planta 100, 208–221 (1971). https://doi.org/10.1007/BF00387037
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00387037