C3 plants exhibiting C4 traits.

AB - The implications of a reduced quantum yield (initial slope of the photosynthetic light response curve) in C4 plants and temperature dependence of quantum yield in C3 plants on total canopy primary production were investigated using computer simulations. Since reduced quantum yield represents the only known disadvantage of the C4 photosynthetic pathway, simulations were conducted with grass canopies (high LAI and hence photosynthesis in most leaves will be light-limited) to see if quantum yield is a significant factor in limiting the primary production and thus distributions of C4 grasses. Simulations were performed for three biogeographical or environmental conditions: the Great Plains region of North America, the Sonoran Desert of North America, and shade habitats. For all three cases, the simulations predicted either spatial or temporal gradients in the abundances of C4 grasses identical to the abundance patterns of C4 grasses observed in the field. It is thus concluded that while the C4 photosynthetic mechanism may be highly advantageous in specific environments, it may be disadvantageous in others.

CAM plants need more energy to fix CO than C3 or C4 plants.

von Caemmerer S and Evans JR (2010) Enhancing C3 photosynthesis. Plant Physiology 154: 589–592.

Temperature response of photosynthesis in C3, C4, and …

The connection to hot and dry conditions comes from the fact that all the plants will close their stomata in hot and dry weather to conserve moisture, and the continuing fixation of carbon from the air drops the CO2 dramatically from the atmospheric concentration of nominally 380 ppm (2004 value). If the CO2 compensation point is lower on the above scale, the plant can operate in hotter and dryer conditions. The limits are placed by the fact that begins to fix oxygen rather than CO2, undoing the work of photosynthesis. C4 plants shield their rubisco from the oxygen, so can operate all the way down to essentially zero CO2 without the onset of photorespiration.

C3 and C4 photosynthesis | EARTH 131: Food

N2 - Plants assimilate carbon by one of three photosynthetic pathways, commonly called the C3, C4, and CAM pathways. The C4 photosynthetic pathway, found only among the angiosperms, represents a modification of C3 metabolism that is most effective at low concentrations of CO2. Today, C4 plants are most common in hot, open ecosystems, and it is commonly felt that they evolved under these conditions. However, high light and high temperature, by themselves, are not sufficient to favor the evolution of C4 photosynthesis at atmospheric CO2 levels significantly above the current ambient values. A review of evidence suggests that C4 plants evolved in response to a reduction in atmospheric CO2 levels that began during the Cretaceous and continued until the Miocene.

C3 plants have softer leaves and live in shaded and less stressful habitats.

C3 and C4 photosynthesis models: an overview from the ..

The CO is then fixed by the RuBisCo in the bundle sheath cells, and photosynthesis occurs with its resultant sugar via the C3 pathway and the Calvin cycle.The direct C4 pathway...
CO + PEP --> oxaloacetic acid --> malic acid --> to bundle sheath cellsThen in bundle sheath cells, in the presence of RuBisCo, using the Calvin cycle...
CO + PEP --> photosynthesis --> SugarThe combined efficiency of PEP in fixing CO, together with the tightly packed double ring of bundle sheath cells and mesophyll cells (called Kranz anatomy.....

subjected to optimum temperature for photosynthesis during the ..

Cross section C4 leaf.
Whereas the RuBisCo in the C3 plant fixes the CO (rather poorly) and prepares for the photosynthesis process in all the chloroplasts in all the mesophyll cells, the C4 plant has a more efficient way of fixing the CO.It has a much more efficient enzyme called PEP which compared to RuBisCo has a much greater affinity with CO.

Temperature response of photosynthesis in C3, C4 and …

Under these conditions C4 photosynthesis has developed a number of times in a number of plant lines in the 25-30 million years since the late Oligocene, getting to today’s numbers by the end of the Miocene.Assuming that low CO is a pre-condition for the development of C4 plants, paramaters such as increasing aridity, high light habitats, increasing temperature and seasonality, fire, and the distribution of grazing animals, are all thought to play an important part in this evolutionary trend.At temperatures 22C - 30C, Quantum yields for C3 and C4 plants are the same
Temperatures above 30C, quantum yields are greater in C4 plants
Temperatures below 22C, quantum yields are greater in C3 plants.

C4 Plants Adaptation to High Levels of CO2 and to …

As a consequence of this, many C4 plants are grown commercially and are recognized as some of the world’s major crops.
As stated before C4 plants include many grasses and sedges, many weeds including crabgrass and nutgrass.

Here we will talk about the ecology of C3-C4-CAM photosynthesis ..

Note that photorespiration which is in general caused by the uptake of O (oxygen) instead of CO by the RuBisCo enzyme, undoes the good work of photosynthesis in the C3 plant.