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Translocation of Coumarin Across a Graft Union in Sweetclover 1
Author(s) -
Gorz H. J.,
Haskins F. A.
Publication year - 1962
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1962.0011183x000200030023x
Subject(s) - geneticist , library science , biology , computer science , genetics
thesis of coumarin and related compounds in sweetclover (1, 7, 8, 12), little is known of the site or sites within the plant at which coumarin is formed. Weygand and Wendt (12) reported coumarin formation in root cultures of Melilotus officinalis (L.) Lain. when suitable precursors were supplied. Mothes and Kala (9) concluded that scopoletin and umbelliferone, compounds closely related to coumarin, can be synthesized by root cultures of Atropa belladonna L. The experiments cited (9, 12) gave no indication that the roots are the preferred site of synthesis or that synthesis takes place at all in the roots of intact plants. Neither of the studies excluded the possibility of synthesis in other organs. If one assumes that coumarin is not translocated within the plant and that the use or destruction of the compound proceeds at relatively equal rates in all organs, the coumarin contents of the various plant parts might then be used as an indication of amounts of synthesis occurring at the respective sites. The distribution of coumarin in leaves, stems, and roots of ungrafted plants of sweetclover has been investigated by Brink, a Goplen et al. (4), Schaeffer et al. (11), and Akeson. ~ In this paper, data on the coumarin content of grafted sweetclover plants are presented and the significance of this information is discussed. The term coumar~n, as used in this paper, needs some clarification since recent work (6, 10) has disclosed that intact sweetclover plants contain little or no coumarin in the free, molecular form. On the other hand, it is now clear that glycosides of both o-coumaric acid (trans-o-hydroxycinnamic acid) and coumarinic acid (cis-o-hydroxycinnamic acid) are present in sweetclover tissue (7, 8, 10). Hydrolysis of these glycosides releases coumaric and coumarinic acids, both of which contribute to coumarin equivalence values in the fluorometric procedure used. The term coumarin is retained in this paper for convenience and because standards of pure coumarin were used in the assay procedure. It should be emphasized, however, that the glycosides of o-hydroxycinnarnic acid, not molecular coumarin, are present in the intact plant.