Occurrence of C 3 and C 4 Photosynthetic Pathways in North American Grasses

Abstract

A literature survey was made for the occurrence of C, and C, photosynthetic pathways in the United States Gramineae. Distinctive characteristics of the two photosynthetic pathways are discussed. Leaf anatomy, CO, compensation point, net enhancement of photosynthesis in oxygen-deficient atmosphere, QC discrimination, and initial product labeling were criteria selected to evaluate data for 6 subfamilies including 25 tribes, 138 genera, and 632 species. The Arundinoideae, Bambusoideae, Oryzoideae, and Pooideae (Festucoideae) are composed of species with C, pathways. All tribes within the Eragrostoideae have C, pathways with the exception of Unioleae. Within the Panicoideae, the Andropogoneae and all of the Paniceae, excepting the genera Sacciolepus, Isachne, Oplismenus, Amphicatpum, and Panicum, have C, pathways. The subgenus Dichanthelium within Panicum is C, while the Bupanicum subgenus contains plants with both C, and C, photosynthetic pathways. Plant productivity is dependent on several environmental and biological factors. The most important single factor is photosynthesis. A pathway for carbon dioxide (CO;?) fixation was described by Calvin and Bassham (1962) in which CO2 was incorporated into a 6-carbon compound and rapidly converted to a 3-carbon compound, 3-phosphoglyceric acid (3PGA). Previous to discoveries of Kortschalk et al. (1965) and Hatch and Slack (1966), the Calvin cycle (C,, reductive pentose pathway) was considered the major photosynthetic mechanism for carbon (C) fixation. However, Hatch and Slack (1966) described CO;! fixation in which labeled CO;! was first incorporated in 4-carbon compounds (malic, aspartic , or oxaloacetic acid) prior to transfer to sugars by way of 3-phosphoglycerate. The proposed mechanism involved the operation of two interconnected metabolic cycles. Downton (1970) described carbon fixation into Cd-dicarboxylic acids in mesophyll cells and subsequent incorporation into the Calvin cycle located in the bundle sheath cells. Plants (Cd plants) possessing the 4-carbon pathway (also called Cd, dicarboxylic acid, Kranz type, low CO;! compensation, tropical, Hatch and Slack, or p carboxylation pathway) were of tropical ongm and more efficient. They produced two-to threefold more dry matter than plants possessing the 3-carbon pathway (C, plants), especially in relatively sunny, warm, dry climates (Black 197 1). Distinctive characteristics associated with the Ca pathway prompted intensive research in photosynthetic processes of flowering plants. The most important photosynthetic pathways

Changes in Community-Level Riparian Plant Traits over Inundation Gradients, Colorado River, Grand Canyon

“…Seed mass data were compiled from the KEW Royal Botanic Garden Seed Information Database (Royal Botanic Gardens Kew 2016, http://data.kew.org/sid/), and consist of average weight in grams per 1000 seeds. Photosynthetic pathways (C3 or C4) were not found for all species, but if another species in the same genus was available, we assumed the same pathway for the species of interest (Syvertsen et al 1976;Doliner and Jolliffe 1979;Waller and Lewis 1979;Boutton et al 1980).…”

Reconstructed historical land cover and biophysical parameters for studies of land‐atmosphere interactions within the eastern United States

“…The C3 grasses/crops tend to be more active at cool temperatures, less active at high temperatures, use water less efficiently, and be less tolerant of drought than C4 grasses/crops (see the species tabulation and review of Waller and Lewis [1979]). In general, agricultural production has introduced extensive C3 (cool season) vegetation into the eastern United States including C3 crops (e.g., wheat, soybeans, barley, oats, rye, rice, cotton, and peanuts) and C3 pasture/hay (e.g., alfalfa, orchard grass, fescue, perennial ryegrass, and Kentucky bluegrass).…”

Using eastern gamagrass to construct diets that limit intake and caloric density for dairy replacement heifers

“…Eastern gamagrass (EGG; Tripsacum dactyloides L.) is a perennial bunch-type grass that is a distant relative of corn (Bates et al, 1981), and possesses the C4 photosynthetic pathway (Waller and Lewis, 1979). Generally, it is noted for adaptability to moist soil conditions (Stubbendieck et al, 1982), as well as high production potential (Brejda et al, 1996;Brejda et al, 1997;Mashingo et al, 2008), responsiveness to N fertilization (Brejda et al, 1996), and suitability with regard to conservation as silage (Brejda et al, 1994;Coblentz et al, 1999;Eun et al, 2003).…”