Differences in Rubisco and Chlorophyll Content among Tissues and Growth Stages in Two tomato (Lycopersicon esculentum Mill.) Varieties
1Institute of Natural Resources and Agrobiology of Salamanca, IRNASA–CSIC, Apartado 257, 37071 Salamanca, Spain; e-mails: ruben.vicente@irnasa.csic.es; rosa.morcuende@irnasa.csic.es
2University of Salamanca, Department of Plant Physiology, Campus Miguel de Unamuno, 37008 Salamanca, Spain; e-mail: babiano@usal.es
Abstract:
Ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco) is a key enzyme in the photosynthetic assimilation of CO2 and the most abundant leaf protein. The amounts ofchlorophyll (chl) and Rubisco have often been considered, respectively, as indices of light harvesting and Calvin cycle capacities of leaves. The purpose of this study was to analyze the changes in chlorophyll content and the level of Rubisco protein in various plant tissues at different growth stages in two tomato (Lycopersicon esculentum Mill.) varieties. The results show an increase of the amount of both chlorophyll and Rubisco protein at vegetative growth stages (leaf expansion), which was followed by a gradual decline during anthesis, probably as a consequence of changes in the balance of their synthesis and degradation reported previously –Rubisco could be remobilized and reused in the production of reproductive structures. However, the increase in the amount of Rubisco and chlorophyll at ripening stage (more in Tres Cantos variety) contrasts with the decrease reported in other studies when degradation is becoming predominant during senescence.
Key words:
chlorophyll, growth stages, leaf nitrogen, protein, Rubisco, tissues, tomato