C4 carbon fixation or the Hatch–Slack pathway is one of three known photosynthetic processes of carbon fixation in plants. It owes the names to the 1960s discovery by Marshall Davidson Hatch and Charles Roger Slack that some plants, when supplied with 14CO2, incorporate the 14C label into four-carbon molecules first.
Photorespiration (also known as the oxidative photosynthetic carbon cycle or C2 cycle) refers to a process in plant metabolism where the enzyme RuBisCO oxygenates RuBP, wasting some of the energy produced by photosynthesis. The desired reaction is the addition of carbon dioxide to RuBP (carboxylation), a key step in the Calvin–Benson cycle, but approximately 25% of reactions by RuBisCO instead add oxygen to RuBP (oxygenation), creating a product that cannot be used within the Calvin–Benson cycle. This process lowers the efficiency of photosynthesis, potentially lowering photosynthetic output by 25% in C3 plants. Photorespiration involves a complex network of enzyme reactions that exchange metabolites between chloroplasts, leaf peroxisomes and mitochondria.
C3 carbon fixation is the most common of three metabolic pathways for carbon fixation in photosynthesis, the other two being C4 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:
Dactylis is a genus of Eurasian and North African plants in the bluegrass subfamily within the grass family. Dactylis is native to North Africa, they are found throughout the world, and are an invasive species. They are known in English as cock's-foot or cocksfoot grasses, also sometimes as orchard grasses.
Chloridoideae is one of the largest subfamilies of grasses, with roughly 150 genera and 1,600 species, mainly found in arid tropical or subtropical grasslands. Within the PACMAD clade, their sister group is the Danthonioideae. The subfamily includes widespread weeds such as Bermuda grass or goosegrass, but also millet species grown in some tropical regions, namely finger millet and teff.
Centotheceae is a small tribe of grasses with six species in two genera, distributed in Africa and Asia. It belongs to a basal lineage in subfamily Panicoideae, sometimes referred to as "centothecoid clade". Unlike many other clades in the subfamily Panicoideae, they use the C3 photosynthetic pathway.
Dactylis glomerata is a species of flowering plant in the grass family Poaceae, commonly known as cock's-foot, orchard grass, or cat grass (due to its popularity for use with domestic cats). It is a cool-season perennial C3 bunchgrass native throughout most of Europe, temperate Asia, and northern Africa.
Alloteropsis is a genus of Old World plants in the grass family.
The BOP clade (sometimes BEP clade) is one of two major lineages (or clades) of undefined taxonomic rank in the grasses (Poaceae), containing more than 5,400 species, about half of all grasses. Its sister group is the PACMAD clade; contrary to many species of that group who have evolved C4 photosynthesis, the BOP grasses all use the C3 photosynthetic pathway.
The PACMAD clade (previously PACCMAD, PACCAD, or PACC) is one of two major lineages (or clades) of the true grasses (Poaceae), regrouping six subfamilies and about 5700 species, more than half of all true grasses. Its sister group is the BOP clade. The PACMAD lineage is the only group within the grasses in which the C4 photosynthesis pathway has evolved; studies have shown that this happened independently multiple times.
The evolution of photosynthesis refers to the origin and subsequent evolution of photosynthesis, the process by which light energy is used to assemble sugars from carbon dioxide and a hydrogen and electron source such as water. The process of photosynthesis was discovered by Jan Ingenhousz, a Dutch-born British physician and scientist, first publishing about it in 1779.
Paspaleae is a tribe of the Panicoideae subfamily in the grasses (Poaceae), native mainly to the tropical and subtropical Americas but with a number of species introduced to other regions. It includes roughly 680 species in 39 genera. Species in this tribe use either of the C3 or C4 photosynthetic pathways.
Steyermarkochloeae is a tribe of the Panicoideae subfamily in the grasses (Poaceae), native to tropical South America. There are only two species in two genera, Arundoclaytonia and Steyermarkochloa. The tribe probably belongs to a basal lineage within the subfamily. Species in this tribe use the C3 photosynthetic pathway.
Tristachyideae is a tribe of the Panicoideae subfamily in the grasses (Poaceae), native to tropical and subtropical regions of Africa, Asia, and South America. There are around 70 species in eight genera. The tribe belongs to a basal lineage within the subfamily, and its genera were previously placed in tribes Arundinelleae or Paniceae, subfamily Arundinoideae, or the now-obsolete subfamily Centothecoideae. Species in this tribe use the C4 photosynthetic pathway.
Zeugiteae is a tribe of the subfamily Panicoideae in the grasses (Poaceae), native to Africa, Asia, Australasia, South and Central America. There are 18 species in four genera. The tribe belongs to a basal lineage within the subfamily. Species in this tribe use the C3 photosynthetic pathway.
Chasmanthieae is a small tribe of grasses in the subfamily Panicoideae. It belongs to a basal lineage within the subfamily and has only seven species in two genera, Bromuniola with one species in Africa and Chasmanthium from North America. They all use the C3 photosynthetic pathway.
Cyperochloeae is a small tribe of grasses in the Panicoideae subfamily, found in Australia. It belongs to a basal lineage within the subfamily and has only two species in two monotypic genera, Cyperochloa and Spartochloa. They use the C3 photosynthetic pathway.
Dichanthelium oligosanthes, known as Heller's rosette grass, fewanther obscuregrass, and few-flowered panicgrass, is a frost-tolerant, perennial grass species native to North America. It is found primarily in the contiguous United States with specimens also reported in British Columbia and Alberta in Canada, as well as south of the Rio Grande in northern Mexico. D. oligosanthes is most frequently in partially shaded glens within woods, recently cut forests, and grassy banks.
Jeremy James Bruhl is an Australian botanist. He is an emeritus professor in the School of Environmental and Rural Science at the University of New England and director of the N.C.W. Beadle Herbarium which holds c.110,000 plant specimens.
