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Leaf anatomy in most C 4 plants. A: Mesophyll cell B: Chloroplast C: Vascular tissue D: Bundle sheath cell E: Stoma F: Vascular tissue 1. CO 2 is fixed to produce a four-carbon molecule (malate or aspartate). 2. The molecule exits the cell and enters the bundle sheath cells. 3. It is then broken down into CO 2 and pyruvate.
This pathway allows C4 photosynthesis to efficiently shuttle CO 2 to the RuBisCO enzyme and maintain high concentrations of CO 2 within bundle sheath cells. These cells are part of the characteristic kranz leaf anatomy, which spatially separates photosynthetic cell-types in a concentric arrangement to accumulate CO 2 near RuBisCO. [21]
Maize (Zea mays, Poaceae) is the most widely cultivated C 4 plant.[1]In botany, C 4 carbon fixation is one of three known methods of photosynthesis used by plants. C 4 plants increase their photosynthetic efficiency by reducing or suppressing photorespiration, which mainly occurs under low atmospheric CO 2 concentration, high light, high temperature, drought, and salinity.
Calvin–Benson cycle. C 3 carbon fixation is the most common of three metabolic pathways for carbon fixation in photosynthesis, the other two being C 4 and CAM.This process converts carbon dioxide and ribulose bisphosphate (RuBP, a 5-carbon sugar) into two molecules of 3-phosphoglycerate through the following reaction:
Rates of leaf photosynthesis were shown to increase by 30–50% in C3 plants, and 10–25% in C4 under doubled CO 2 levels. [40] The existence of a feedback mechanism results a phenotypic plasticity in response to [CO 2 ] atm that may have been an adaptive trait in the evolution of plant respiration and function.
The pineapple is an example of a CAM plant.. Crassulacean acid metabolism, also known as CAM photosynthesis, is a carbon fixation pathway that evolved in some plants as an adaptation to arid conditions [1] that allows a plant to photosynthesize during the day, but only exchange gases at night.
The C4 grasses have a photosynthetic pathway, linked to specialized Kranz leaf anatomy, which allows for increased water use efficiency, rendering them better adapted to hot, arid environments. [13] The C3 grasses are referred to as "cool-season" grasses, while the C4 plants are considered "warm-season" grasses. [8]: 18–19
Annuals or subshrubs, they can be distinguished from closely related taxa such as Bassia by their flattened perianths which have four lobes, inflorescences with multicellular glandular hairs, a distinct C 4 leaf anatomy type (called the Camphorosma type), and a chromosome count of 2n = 12. [5] [6]