C4 photosynthesis affords higher photosynthetic carbon conversion efficiency than C3 photosynthesis and it therefore represents an attractive target for engineering efforts aiming to improve crop productivity. To this end, blueprints are required that reflect C4 metabolism as closely as possible. Such blueprints have been derived from comparative transcriptome analyses of C3 species with relate...

During the last ice age, CO2 concentration ([CO2]) was 180-200 micromol/mol compared with the modern value of 380 micromol/mol, and global temperatures were approximately 8 degrees C cooler. Relatively little is known about the responses of C3 and C4 species to long-term exposure to glacial conditions. Here Abutilon theophrasti Medik. (C3) and Amaranthus retroflexus L. (C4) were grown at 200 mi...

background: the serum levels of c 3 , c4, and the total hemolytic activity of complement system (ch50) of patients ex­posed to mustard gas (mg) in the battlefield were measured in this study. methods: c3 and c4 were measured by single radial immunodifusion and ch50 was evaluated according to total hemolytic activ­ity of the serum. results:   the serum levels of c 3 showed a significant increase...

The C4 photosynthetic pathway uses water more efficiently than the C3 type, yet biogeographical analyses show a decline in C4 species relative to C3 species with decreasing rainfall. To investigate this paradox, the hypothesis that the C4 advantage over C3 photosynthesis is diminished by drought was tested, and the underlying stomatal and metabolic mechanisms of this response determined. The ef...

Rubisco (for ribulose-1,5-bisphosphate carboxylase/oxygenase), the enzyme that catalyzes the first major step in carbon fixation, is notoriously inefficient in this role, owing to its function as an oxygenase as well as a carboxylase. Photorespiration, the pathway followed when Rubisco catalyzes the oxygenation rather than carboxylation of the substrate ribulose-1,5-bisphosphate, can reduce the...

Thermal-based germination models are widely used to predict germination rate and germination timing of plants. However, comparison of model parameters between large numbers of species is rare. In this study, seeds of 27 species including 12 C4 and 15 C3 species were germinated at a range of constant temperatures from 5 °C to 40 °C. We used a modified thermal time model to calculate germination ...

Formation of a photorespiration-based CO2-concentrating mechanism in C3-C4 intermediate plants is seen as a prerequisite for the evolution of C4 photosynthesis, but it is not known how efficient this mechanism is. Here, using in vivo Rubisco carboxylation-to-oxygenation ratios as a proxy to assess relative intraplastidial CO2 levels is suggested. Such ratios were determined for the C3-C4 interm...

The North American tallgrass prairie is composed of a diverse mix of C3 and C4 plant species that are subject to multiple resource limitations. C4 rasses dominate this ecosystem, purportedly due to greater photosynthetic capacity and resource-use efficiency associated with C4 photosynthesis. e tested the hypothesis that intrinsic physiological differences between C3 and C4 species are consisten...

Leaves of C4 crops usually have higher radiation, water and nitrogen use efficiencies compared to the C3 species. Engineering C4 traits into C3 crops has been proposed as one of the most promising ways to repeal the biomass yield ceiling. To better understand the function of C4 photosynthesis, and to identify candidate genes that are associated with the C4 pathways, a comparative transcription ...