ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Seasonal changes of Rubisco content and activity in Fagus sylvatica and Picea abies affected by elevated CO₂ concentration

Miroslav Hrstka, Otmar Urban, and Libor Babák

Faculty of Chemistry, Brno University of Technology, Purkyňova 118, 612 00 Brno, Czech Republic

E-mail: hrstka@fch.vutbr.cz

Abstract: We studied Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) content and activity in juvenile tree species — broadleaved Fagus sylvatica L. and coniferous Picea abies (L.) Karsten exposed for three growing seasons to ambient (A = 385 μmol mol⁻¹) and elevated (E = 700 μmol mol⁻¹) CO₂ concentrations. Rubisco content was determined by the SDS-PAGE method, Rubisco activity was assayed spectrophotometrically. The highest content of Rubisco enzyme in F. sylvatica was measured immediately after full leaf development followed by a gradual decrease throughout the growing season. By contrast, Rubisco content in P. abies increased markedly during the growing season. In both tree species, down-regulation of Rubisco content in trees cultivated under elevated CO₂ concentration was observed. Rubisco activity was stimulated in F. sylvatica by E treatment but not in P. abies. Because no significant differences were found in Rubisco activation state between A and E, we assume that stimulation of Rubisco activity in E is not a consequence of higher carbamylation but could be caused by the release of inhibitors from active sites of Rubisco under elevated CO₂.

Keywords: Rubisco content – Rubisco activity – seasonal changes – elevated CO2 concentrations – Fagus sylvatica – Picea abies

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-012-0188-5

Chemical Papers 66 (9) 836–841 (2012)