engleski

Development of the photosynthetic apparatus in fruit-bearing flowers of the Christmas rose

The influence of fruit development on chloroplast formation in the perianth of the Christmas rose (Helleborus niger L.) was studied using electron microscopy and biochemical methods. In this species the sepals, which are white at anthesis, persist until the seeds are ripe and become intensely green during that period. This color change is due to the fact that the leucoplasts present at anthesis start turning into chloroplasts, after pollination. During the greening period the plastids acquire the complete set of pigments and proteins of the photosynthetic apparatus. The photosynthetic activity of green sepals (expressed on a fresh weight or dry weight basis) is about half of that in the young leaves present at the same time. The metamorphosis of the sepals into photosynthetically active organs only occurs in fruit-bearing flowers and is arrested at a very early stage in controls in which the pistils are removed before pollination. The green sepals likely provide a significant part of the assimilates required for seed filling.

Helleborus niger L.; Christmas rose; carotenoid; chlorophyll; morphogenesis; perianth; photosynthesis; plastid metamorphosis

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