engleski

Regulation of morphogenesis in fertilized Helleborus flowers

On fertilization, the flowers of Helleborus niger L. change as follows. 1. the peduncle elongates, 2. the sepals (the showy part of the perianth at anthesis) spread, and 3. they develop photosynthetic activity. These processes can be arrested by removing the pistils or developing fruit. In such depistillated flowers elongation of the peduncle can be most effectively induced by auxins. In the same material, the metamorphosis of the sepals is promoted by exogenous gibberellins and cytokinins with the former more effective in the spreading response and the latter in the greening process. In intact fertilized flowers, these hormones may well be supplied by the developing fruit. Indeed, premilimary analyses suggest a significant increase in zeatin-type cytokinins, both in the pistils following pollination and in simultaneously sampled sepals.

Helleborus niger; Christmas rose; flower metamorphosis after pollination; phytohormone; auxin; cytokinin; gibberellin

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