Acta Botanica Croatica, Vol. 63 No. 2, 2004.
Original scientific paper
Biochemical and functional characteristics of the photosynthetic apparatus in vegetative buds and mature needles of Norway spruce (Picea abies L. Karst.)
H. Lepeduš
V. Cesar
Abstract
The biochemical characteristics and functioning of the photosynthetic apparatus in two developmental stages of spruce needles (vegetative buds and mature needles) were compared. Biochemical analysis included quantification of the photosynthetic pigments and immunodetection of the NAPDH-protochlorophyllide oxidoreductase (POR). Photosynthetic performance was monitored as the oxygen production at different light levels applied. Two POR isoforms were detected in buds while only one isoform was present in mature needles. The POR polypeptides in buds were expressed at different levels: the polypeptide of lower molecular mass had a level that was more enhanced than that of higher molecular mass. The most intensive POR signal was observed in mature needles. Concentrations of chlorophylls and carotenoids that were higher in mature needles than in vegetative buds were in accordance with observed POR expression. This reflected on the photosynthetic activity of the investigated organs. Although the chloroplasts in vegetative
buds revealed the capability of photosynthesising, the compensation of respiration was not observed even at the highest light level (1100 molPHOTONS m–2s–1) applied. In contrast, mature needles ompensated for respiration successfully at low light level (30
molPHOTONS m–2s–1). Our study showed that chloroplasts in vegetative buds are photosynthetically competent, but limited by their molecular and biochemical background.
Keywords
Picea abies; photosynthesis; oxygen production; respiration; NADPH-protochlorophyllide oxidoreductase; immunodetection; chlorophylls; carotenoids
Hrčak ID:
3443
URI
Publication date:
15.10.2004.
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