Quinoa (Chenopodium quinoa; , from Quechua kinwa or kinuwa) is a flowering plant in the amaranth family. It is a herbaceous annual plant grown as a crop primarily for its edible seeds; the seeds are high in protein, dietary fiber, B vitamins and dietary minerals especially potassium and magnesium in amounts greater than in many grains. Quinoa is not a grass but rather a pseudocereal botanically related to spinach and amaranth (Amaranthus spp.), and originated in the Andean region of northwestern South America. It was first used to feed livestock 5,200–7,000 years ago, and for human consumption 3,000–4,000 years ago in the Lake Titicaca basin of Bolivia and Peru. The plant thrives at high elevations and produces seeds that are rich in protein. Almost all production in the Andean region is done by small farms and associations. Its cultivation has spread to more than 70 countries, including Kenya, India, the United States, and European countries. As a result of increased consumption in North America, Europe, and Australasia, quinoa crop prices tripled between 2006 and 2014, entering a boom and bust cycle. The quinoa monoculture that arose from increased production, combined with climate change effects in the native Andean region, created challenges for production and yield, and led to environmental degradation.
Description Chenopodium quinoa is a dicotyledonous annual plant, usually about 1–2 m (3–7 ft) high. It has broad, generally powdery, hairy, lobed leaves, normally arranged alternately. The woody central stem is branched or unbranched depending on the variety and may be green, red or purple. The flowering panicles arise from the top of the plant or from leaf axils along the stem. Each panicle has a central axis from which a secondary axis emerges either with flowers (amaranthiform) or bearing a tertiary axis carrying the flowers (glomeruliform). These are small, incomplete, sessile flowers of the same colour as the sepals, and both pistillate and perfect forms occur. Pistillate flowers are generally located at the proximal end of the glomeruli and the perfect ones at the distal end of it. A perfect flower has five sepals, five anthers and a superior ovary, from which two to three stigmatic branches emerge. The green hypogynous flowers have a simple perianth and are generally self-fertilizing, though cross-pollination occurs. In the natural environment, betalains serve to attract animals to generate a greater rate of pollination and ensure, or improve, seed dissemination. The fruits (seeds) are about 2 mm (1⁄16 in) in diameter and of various colors — from white to red or black, depending on the cultivar. In regards to the "newly" developed salinity resistance of C. quinoa, some studies have concluded that accumulation of organic osmolytes plays a dual role for the species. They provide osmotic adjustment, in addition to protection against oxidative stress of the photosynthetic structures in developing leaves. Studies also suggested that reduction in stomatal density in reaction to salinity levels represents an essential instrument of defence to optimize water use efficiency under the given conditions to which it may be exposed.
Taxonomy The species Chenopodium quinoa was first described by Carl Ludwig Willdenow (1765–1812), a German botanist who studied plants from South America, brought back by explorers Alexander von Humboldt and Aimé Bonpland. Quinoa is an allotetraploid plant, containing two full sets of chromosomes from two different species which hybridised with each other at one time. According to a 1979 study, its presumed ancestor is either Chenopodium berlandieri, from North America, or the Andean species Ch. hircinum. On the other hand, morphological features relate Ch. quinoa of the Andes and Ch. nuttalliae of Mexico. More recent studies indicate that Andean and Mexican quinoas were independently domesticated and that both derive from wild North American C. berlandieri, carrying the genome formula AABB, and are likely derived from a hybridization several million years ago between AA and BB diploids closely related to the modern C. subglabrum and C. suecicum, respectively. Quinoa's wild South American ancestor, C. hircinum, may have been translocated from North to South America via zoochory. A feral-weedy quinoa, Ch. quinoa var. melanospermum, is known from South America, but no equivalent closely related to Ch. nutalliae has been reported from Mexico so far. Studies regarding the genetic diversity of quinoa suggest that it may have passed through three bottleneck genetic events, with a possible fourth to come:
The first occurred when the species was created, as its two diploid ancestors underwent a hybridization followed by chromosome doubling, this new species was genetically isolated from its parent species, and thus lost a great deal of genetic diversity. As stated above, these ancestors were possibly C. subglabrum (AA) and C. suecicum (BB) and therefore not the Andean diploid pseudo cereal Chenopodium pallidicaule (cañahua). A second bottleneck may have occurred when quinoa was domesticated from its wild tetraploid ancestor, C. hircinum. It might have been domesticated twice: once in the high Andes and a second time in the Chilean and Argentinean lowlands. A third bottleneck can be considered "political", and has lasted more than 400 years, from the Spanish conquest of the new continent until the present time. During this phase quinoa has been replaced with maize, marginalized from production processes possibly due to its social and religious roles for the indigenous populations of South America, but also because it is difficult to process (dehusk) compared with maize. In the 21st century, a fourth bottleneck event may occur, as traditional farmers migrate from rural zones to urban centers, which exposes quinoa to the risk of further genetic erosion. Better breeding may also result in loss of genetic diversity, as breeders would be expected to reduce unwanted alleles to produce uniform cultivars, but cross-breeding between local landraces has and will likely produce high-diversity cultivars.
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