engleski

Biochemical and functional characteristics of the photosynthetic apparatus in vegetative buds and mature needles of Norway spruce (Picea abies L. Karst.)

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 NADPH-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 observes 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 the photosynthesising, the compensation of respiration was not observed even at the highest light level (1100 μ mol_PHOTONS m-2 s-1) applied. In contrast, mature needles compensated for respiration successfully at low light level (30 μ mol_PHOTONS m-2 s-1). Our study showed that chloroplasts in vegetative buds are photosynthetically competent, but limited by their molecular and biochemical background.

Picea abies ; photosynthesis ; oxigen production ; respiration ; NADPH-protochlorophyllide oxidoreductase ; immunodetection ; chlorophylls ; carotenoids

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