Domestication low in protien quality for supplying essential

Domestication
of  Wheat (Triticum aestivum):

 

Wheat is a grass broadly cultivated for
its seeds, a cerel grain which is a global staple food. There are
many types of wheat crop which together make up the genus Triticum;
the most widely grown is common wheat.

 

Archaeological Records:

The ancient records suggests
that wheat was first cultivated in the regions of the firtile cresent around
9600 BCE. Botanically, the wheat kernel is a type of fruit called
a cryopsis.

Wheat is grown on
more land area than any other food crop (220.4 million hectraes,
2014). World trade in wheat is greater than for all other crops
combined. In 2016, world production of wheat was 749 million tonnes, making
it the second most-produced cereal after Zea mays. Since 1960, world production of wheat and other
grain crops has become three times and is
believe to grow more over through the middle of the 21st
century. Global demand for wheat is expand due to the unique viscoelastic and
adhesive properties of gluten proteins, which facilitate the
production of processed foods, whose consumption is increasing as a result of
the global industrialization process and the westrinization of diet

 

Wheat source:

Wheat is an important
source of carbohydrates. internationally, it is the leading source of
vegetal protein in human food, having a protein content of about 13%, which is
relatively high compared to other major cereals, but relatively low in
protien quality for supplying essential amino acid. When eaten as
the whole grain, wheat is a source of multiple nutrients and dietery
fiber.

In a small part of
the general population, gluten – the major part of wheat protein – can
trigger celiac disease, non coliac disease gluten senstivity, gluten
antaxia and dermatitis hermetifirms.

Reference : Wikipedia

 

Domestication
of  Wheat by their chromosomes structure:

It
was determined nearly a century ago that the cultivated wheat species of the
genus Triticum have chromosome numbers of 2n = 14, 28, and 42. This indicated
that the basic Triticeae genome was organized into seven chromosomes (1x = 7)
and the various Triticum species consisted of diploids (2n = 2x = 14),
tetraploids (2n = 4x = 28), and hexaploids (2n = 6x = 42) (Sax 1922; Kimber and
Sears 1987). The diploid progenitors and close relatives of modern wheat
radiated from a common ancestor about 3 million years ago (MYA) and gave rise
to the Triticum and Aegilops taxa. The Triticum group consisted of the A-genome
diploids T. urartu Tumanian ex Gandylian (2n = 2x = 14, AA (the capital letters
represent the genome constitution)) and T. monococcum ssp. aegilopoides (Link)
Thell. (2n = 2x = 14, AA). Johnson and Dhaliwal (1976) determined that they are
valid biological species. Also evolving from the common seven-chromosome
ancestor were numerous diploid Aegilops species including Ae. tauschii Coss.
(2n = 2x = 14, DD) and a progenitor to the Aegilops Sitopsis section, which
gave rise to the S-genome containing Aegilops species including Ae. speltoides
Tausch (2n = 2x = 14, SS). The only domesticated diploid wheat is einkorn (T.
monococcum ssp. monococcum L., 2n = 2x = 14, AmAm), which was domesticated from
ssp. aegilopoides through the acquisition of a non-brittle rachis.

 

 

 

 

 The evolution and formation of the cultivated
forms of polyploid wheat followed two basic lineages, both of which involved
two amphiploidization events. These events resulted from the hybridization of
two different species followed by spontaneous chromosome doubling of the F1
hybrid through the functioning of meiotic restitution division (non-reduced)
gametes. One lineage began with hybridization of T. urartu (Dvorak et al. 1993)
and Ae. speltoides, or a close relative thereof (Sarkar and Stebbins 1956;
Riley et al. 1958), which led to the formation of the wild emmer wheat T. timopheevii
ssp. araraticum Jakubz. (2n = 4x = 28, AAGG) containing a pair of A genomes
from T. urartu and a pair of G genomes, which are considered to be a divergent
form of the S genome of the Aegilops progenitor (Rodriquez et al. 2000). T.
timopheevii ssp. araraticum has a brittle rachis conferred by the Br13A gene. A
mutation in Br13A led to a non-brittle rachis and the domestication of this
form to T. timopheevii ssp. timopheevii (Zhuk.) Zhuk (2n = 4x = 28, AAGG). T.
timopheevii was never cultivated as a significant crop and grows only in a
limited region of Georgia. Therefore, it was probably a secondary domesticate
(Nesbitt and Samuel 1996).

Reference : 
San Francis.

Domestication
of  Rice (Oryza sativa)

 

From a wild Asian grass to a refined crop that is the staple diet of
half the world’s population, the domestication of Oryza sativa spans
centuries, but the grain’s ancestry is hotly contested.

Asian civilization was built on rice — on Oryza sativa, to
be exact. The crop, which today is the primary food source for half of the
world’s population, transformed nomadic hunter-gatherers into stay-at-home
farmers, spawned the first urban centres and built empires and dynasties.
“Probably more so than any crop, it drove societies and economies to become
densely populated, potentially more urbanized, and it also transformed
landscapes,” says Dorian Fuller, an archeao botanist at University College
London.

Despite — or possibly because of —
rice’s primacy, the history of the grain remains controversial, with little
agreement on where, when and how many times humans tamed O. sativa in
Asia to create the world’s most important crop. (The only other domesticated
rice species, Oryza glaberrima, has its roots in Africa. See ‘The second story’.) “Almost every part of Asia had been
pinpointed as the area where rice originated,” says Michael Purugganan, an
evolutionary geneticist at New York University who studies rice domestication.
Unravelling the history of rice in Asia would illuminate a turning point in
human civilization and give scientists fresh insight that could help improve
the crop for the future. Thanks to advances in genetics and to new archaeological
finds, that history is becoming clearer — and it is a lot more complicated and
convoluted than anyone thought.

Reference : https://www.nature.com › nature › outlook

 

Domestication
of  Maize (Zea  mays)

 

Maize (Zea mays) is a plant of enormous modern-day
economic importance as foodstuff and alternative energy source. Scholars agree
that maize was domesticated from the plant teosinte (Zea mays spp. parviglumis)
in central America at least as early 9,000 years ago. In the Americas, maize is
called corn, somewhat confusingly for the rest of the English-speaking world,
where ‘corn’ refers to the seeds of any grain, including barley, wheat or
rye.

The process of
maize domestication radically changed it from its origins. The seeds of wild
teosinte are encased in hard shells and arranged on a spike with five to seven
rows, a spike that shatters when the grain is ripe to disperse its seed. Modern
maize has hundreds of exposed kernels attached to a cob which is completely
covered by husks and so cannot reproduce on its own. The morphological change
is among the most divergent of speciation known on the planet, and it is only
recent genetic studies that have proven the connection.

The earliest
undisputed domesticated maize cobs are from Guila
Naquitz cave in Guerrero, Mexico, dated about 4280-4210 cal BC. The
earliest starch
grains from domesticated maize have been found in the Xihuatoxtla
Shelter, in the Rio Balsas valley of Guerrero, dated to ~9,000 cal
BP.

Agricultural Traditions

As maize was
spread outside of its roots in central America, it became part of already
existing agricultural traditions, such as the Eastern Agricultural complex,
which included pumpkin (Cucurbita sp), chenopodium and sunflower(Helianthus).

The earliest
direct-dated maize in the northeast is the 399–208 cal BC, in the Finger Lakes
region of New York, at the Vinette site. Other early appearances are
Meadowcroft Rockshelter

 

Reference : https://www.thoughtco.com › … › Social Sciences
› Archaeology › Domestication

 

Domestication
of  Oat (Avena sativa)

 

Oat, usually in the plural as oats, is any of the
various plants of the genus Avena of
the grass family
(Poaceae),
some of which are widely cultivated for their edible seeds (botanically a type
of simple dry fruitcalled a caryopsis). In particular, oats refers to the
common cereal plant Avena sativa, and to its
edible grains, which are used for food, livestock feed, hay,
pasture, and silage. Other well known plants of this genus are wild oat (A.
fatua), red oat (A. byzantina), and wild red oat (A
steriles). In all, there are about ten to fifteen Avena species
and subspecies. This article will mainly be about A. sativa, which
is one of the most important grain crops
worldwide.

While oats are suitable
for human consumption, used particularly as oatmeal and rolled oats, one of the
most common uses is as livestock feed.
In the United States, less than five percent of the total production is used
for food, with most oats used for livestock feed (CNCPP 1999). Oats make up a
large part of the diet of horses and
are regularly fed to cattle as
well. Oats are also used in some brands of dog and chicken feed.

Oats are the third most
important grain crop in the United States (CNCPP 1999) and are seventh in
weight of production worldwide, after maize,
rice, wheat, barley, sorghum,
and millet (FAO 2008). In 2007, almost 26 million metric tons of oats were
produced worldwide (FAO 2008).

 

Reference : www.newworldencyclopedia.org/entry/Oat

 

Domestication
of  Barley(Hordeum  vulgare)

 

Barley (Hordeum vulgare L.)
is one of the founder crops of Old World agriculture. Archaeological remains of
barley grains found at various sites in the Fertile Crescent (Zohary and Hopf
1993 ; Diamond 1998 ) indicate that the crop was domesticated
about 8000 b.c. (b.c. = calibrated dates and b.c. = uncalibrated dates, where
calibration refers to normalization of radiocarbon age estimates based on
trees’ growth rings; Nesbitt and Samuel 1996 ). The wild relative of
the plant is known as Hordeum spontaneum C.
Koch. In modern taxonomy, H. vulgare L.
and H. spontaneum C. Koch, as well as Hordeum agriocrithon Åberg, are considered
subspecies of H. vulgare (Bothmer and
Jacobsen 1985 ). For reasons given by Nevo (1992) , we will
follow the traditional nomenclature, which considers separate taxa. Hordeum spontaneum and H. vulgare are morphologically similar, with the
cultivated form having broader leaves, shorter stem and awns, tough ear rachis,
a shorter and thicker spike, and larger grains (Zohary 1969 ). The wild
progenitor H. spontaneum is still
colonizing its primary habitats in the Fertile Crescent from Israel and Jordan
to south Turkey, Iraqi Kurdistan, and southwestern Iran (Harlan and Zohary
1966 ; Nevo 1992 ). In the same area, H. spontaneum also occupies an array of secondary
habitats, such as open Mediterranean maquis, abandoned fields, and roadsides.
Similar marginal habitats have been more recently colonized by H. spontaneum in the Aegean region, southeastern
Iran, and central Asia, including Afghanistan and the Himalayan region (Zohary
and Hopf 1993 ). On the map given by Bothmer et al. (1995) , for
example, H. spontaneum is reported in
Greece, Egypt, southwestern Asia, and eastward as far as southern Tajikistan
and the Himalayas. Indeed, the Himalayas, Ethiopia, and Morocco have
occasionally been considered centers of barley domestication (Åberg
1938 ; Bekele 1983 ; Molina-Cano et al. 1987 ).

We revisited the domestication history of barley
using the approach which proved successful in locating the site of Einkorn
wheat domestication (Heun et al. 1997 ). The method assumes that (1) DNA
markers allow a measure of genetic distances; (2) within a wild species,
geographical populations are genetically different; (3) the localities in which
wild accessions were collected are known; and (4) the progenitors of crop
plants have not undergone significant genetic change during the past 10,000
years (Zohary and Hopf 1993 ). The last assumption can be verified by a
careful morphological analysis to exclude cases of introgression of cultivated
germplasm into wild accessions. Our ultimate goal was to determine whether
barley was domesticated more than once and to pinpoint the region of barley
domestication.

Reference :
https://academic.oup.com/mbe/article/17/4/499/1127626