To understand the effect of heat and drought on three major cereal crops, the physiological and biochemical (i.e., metabolic) factors affecting photosynthesis were examined in rice, wheat, and maize plants grown under long-term water deficit (WD), high temperature (HT) and the combination of both stresses (HT-WD). Diffusional limitations to photosynthesis prevailed under WD for the C3 species, ...

In most cyanobacteria, the gene rbcX is co-transcribed with the rbcL and rbcS genes that code for the large and small subunits of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Previous co-expression studies in Escherichia coli of cyanobacterial Rubisco and RbcX have identified a chaperonin-like function for RbcX. The organization of the rbcLXS operon has, to a certain extent, precl...

High nitrogen (N) supply frequently results in a decreased photosynthetic N-use efficiency (PNUE), which indicates a less efficient use of accumulated Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Chloroplasts are the location of Rubisco and the endpoint of CO2 diffusion, and they play a vital important role in photosynthesis. However, the effects of chloroplast development on phot...

The lability of Rubisco activase function is thought to have a major role in the decline of leaf photosynthesis under moderate heat (<35°C). To investigate this further, we characterized Rubisco activase and explored its role in the previously demonstrated thermal acclimation and inhibition of two genotypes of Acer rubrum originally collected from Florida (FL) and Minnesota (MN). When plants we...

Inhibition of photosynthesis by heat has been linked to the instability of the ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) chaperone, Rubisco activase. Examination of the recombinant enzyme showed that ADP and ATP protected against inactivation, whereas Mg(2+) promoted inactivation. Heating caused aggregation of Rubisco activase characterized by disruption of secondary structure c...

Abscisic acid ((+)-ABA) is a phytohormone involved in the modulation of developmental processes and stress responses in plants. A chemical proteomics approach using an ABA mimetic probe was combined with in vitro assays, isothermal titration calorimetry (ITC), x-ray crystallography and in silico modelling to identify putative (+)-ABA binding-proteins in crude extracts of Arabidopsis thaliana. R...

The activation state of ribulose bisphosphate carboxylase/oxygenase (rubisco) in a lysed chloroplast system is increased by light in the presence of a saturating concentration of ATP and a physiological concentration of CO(2) (10 micromolar). Electron transport inhibitors and artificial electron donors and acceptors were used to determine in which region of the photosynthetic electron transport...

Whole-cell CO2 fixation and ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) activity were determined in Rhodobacter sphaeroides wild-type and mutant strains. There is no obvious difference in the levels of whole-cell CO2 fixation for the wild type, a form I RubisCO deletion mutant, and a form II RubisCO deletion mutant. No ribulose 1,5-bisphosphate-dependent CO2 fixation was detected ...

Rogers et al., 1996; Fischer et al., 1997). In these plants, enzymes responsible for sucrose uptake and assimilation The original maize (Zea mays L.) var. Zacatecas 58 (Z 0 ) on one side, and photosynthetic rates, sucrose synthesis and five composites of cycles 5, 10, 15, 20, and 23 of and transport on the other, have been described as stratified mass selection (Z 5 , Z 10 , Z 15 , Z 20 , and Z...

The temperature response of net CO(2) assimilation rate (A), the rate of whole-chain electron transport, the activity and activation state of Rubisco, and the pool sizes of ribulose-1,5-bisphosphate (RuBP) and 3-phosphoglyceric acid (PGA) were assessed in sweet potato (Ipomoea batatas) grown under greenhouse conditions. Above the thermal optimum of photosynthesis, the activation state of Rubisc...