Journal Article

Developing fruit direct post‐floral morphogenesis in Helleborus niger L.

Branka Salopek‐Sondi, Maja Kovač, Tatjana Prebeg and Volker Magnus

in Journal of Experimental Botany

Published on behalf of Society for Experimental Biology

Volume 53, issue 376, pages 1949-1957
Published in print September 2002 | ISSN: 0022-0957
Published online September 2002 | e-ISSN: 1460-2431 | DOI:
Developing fruit direct post‐floral morphogenesis in Helleborus niger L.

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In fertilized flowers of Helleborus niger L., the sepals (the showy elements of the perianth at anthesis) grow, spread, and turn green, and the peduncles elongate. These processes did not proceed to completion when the pistils were removed at the bud stage, but could be restored by the application of plant growth regulators. Cytokinins and gibberellins stimulated the formation of well‐developed chloroplasts in, and spreading of, the sepals; the gibberellin, GA3, and the auxin, 4‐chloroindole‐3‐acetic acid, promoted peduncle elongation. In fruit‐bearing flowers, on the other hand, paclobutrazol, an inhibitor of gibberellin biosynthesis, reduced chlorophyll formation in the sepals, reversed sepal spreading, and inhibited peduncle elongation. Of the endogenous growth regulators in developing fruit, the following cytokinins were identified: zeatin, dihydrozeatin, N6‐(2‐isopentenyl)adenine and their ribosides and 9‐glucosides. Zeatin riboside drastically increased in abundance (about 200 times), shortly after fertilization, when chlorophyll accumulation in the sepals occurred at the fastest rate, and remained the most prominent identified cytokinin until seed ripening.

Keywords: Key words: Christmas rose, cytokinin analysis, Helleborus niger L., plant growth regulator, post‐floral morphogenesis.

Journal Article.  5529 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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