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Plastid ultrastructure and photosynthesis in greening petaloid hypsophylls
M. Weidner, A. Franz and K. Napp-Zinn
Vol. 163, No. 2 (1985), pp. 164-174
Published by: Springer
Stable URL: http://www.jstor.org/stable/23377544
Page Count: 11
You can always find the topics here!Topics: Plastids, Chloroplasts, Leaves, Greening, Chlorophylls, Photosynthesis, Plants, Thylakoids, Bracts, Spathes
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The ultrastructural and biochemical-physiological aspects of postfloral greening have been studied in hypsophylls of Heliconia aurantiaca Ghiesbr., Guzmania cf. × magnifica Richter and Spathiphyllum wallisii Regel. In all three species the greening of the hypsophylls is due to plastid transformation, chloroplast formation proceeding from the initially different types of plastids. The degradation process of the original plastid structures and the mode of thylakoid formation are distinct in each case. In none of the species do the transformed plastids look identical to the chloroplasts of the corresponding foliage leaves. On a chlorophyll basis, the rate of photosynthesis of the greened hypsophylls surpasses the rate of the leaves considerably in Spathiphyllum, but is much lower in Heliconia (no data for Guzmania). In all species, anatomy, plastid structure, pigments, 77° K-fluorescence emission, ribulose-1,5-bis-phosphate carboxylase activities and short-term photosynthesis 14CO2-assimilation patterns prove the greened hypsophylls to be capable of providing additional carbon to the developing fruits, thus supplementing the import of organic matter from the foliage leaves.
Planta © 1985 Springer