The review incorporates recent information on carbonic anhydrase (CA, EC: 4.2.1.1) pertaining to types, homology, regulation, purification, in vitro stability, and biological functions with special reference to higher plants. CA, a ubiquitous enzyme in prokaryotes and higher organisms represented by four distinct families, is involved in diverse biological processes, including pH regulation, CO2 transfer, ion exchange, respiration, and photosynthetic CO2 fixation. CA from higher plants traces its origin with prokaryotes and exhibits compartmentalization among their organs, tissues, and cellular organelles commensurate with specific functions. In leaves, CA represents 1-20 % of total soluble protein and abundance next only to ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) in chloroplast, facilitating CO2 supply to phosphoenol pyruvate carboxylase in C4 and CAM plants and RuBPCO in C3 plants. It confers special significance to CA as an efficient biochemical marker for carbon sequestration and environmental amelioration in the current global warming scenario linked with elevated CO2 concentrations. and A. Tiwari ... [et al.].
A mixture of ryegrass (Lolium italicum A. Braun) and clover (Trifolium alexandrinum L.) was sown in Eboli (Salerno, Southern Italy) in September 2007. Crop growth, leaf and canopy gas exchange and ecophysiological traits were monitored throughout the growth cycle. The gross primary production (GPP) was not affected by air temperature (T air); on the contrary the ecosystem respiration (R eco) decreased as T air decreased while net ecosystem CO2 exchange (NEE) increased. When was normalized with leaf area index (LAI), GPP decreased with T air, a likely response to cold that down-regulated canopy photosynthesis in order to optimize the light use at low winter temperatures. Net photosynthetic rates (PN), the effective quantum yield of PSII (ΦPSII) and photosynthetic pigment content were higher in clover than ryegrass, in relation to the higher leaf N content. The lower ΦPSII in ryegrass was linked to lower photochemical quenching coefficient (qP) values, due to a reduced number of reaction centres, in agreement with the lowest Chl a content. This behaviour can be considered as an adaptive strategy to cold to avoid photooxidative damage at low temperature rather than an impairment of PSII complexes., L. Vitale ... [et al.]., and V klíčových slovech chybně uvedené jméno Lolium italicum A. Barum