Effect of inorganic carbon supply on the photosynthetic physiology of Gracilaria tenuistipitata
1994
Garcia-Sanchez, M.J. | Fernandez, J.A. | Niell, X.
Gracilaria tenuistipitata Zhang et Xia was cultured for 15 d at low, normal and high inorganic carbon concentrations under constant light, temperature and nutrient conditions. Carbonic anhydrase (CA; EC 4.2.1.1.) activity, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco; EC 4.1.1.39) content, pigment content and C/N ratio were measured, and also the photosynthesis and growth rates. Both Rubisco content and CA activity increased under conditions of low inorganic carbon (C(i)) but decreased at high C(i) with respect to the control. The amount of pigments declined considerably at high C(i) and was slightly higher at low C(i). The maximum rate of photosynthesis and the photosynthetic efficiency increased in low C(i) and the opposite was found at high C(i) concentration. The effects of C(i) concentration on maximum rate of photosynthesis and photosynthetic efficiency are discussed in relation to the variation in pigment and Rubisco contents and CA activity. The data indicate that C(i) may be an important factor controlling the photosynthetic physiology of G. tenuistipitata with regard, not only to the enzymes of C(i) metabolism , but also to the pigment content.
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