Triticeae | |
---|---|
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Monocots |
Clade: | Commelinids |
Order: | Poales |
Family: | Poaceae |
Clade: | BOP clade |
Subfamily: | Pooideae |
Supertribe: | Triticodae |
Tribe: | Triticeae L. |
Genera | |
See text. |
Triticeae is a botanical tribe within the subfamily Pooideae of grasses that includes genera with many domesticated species. Major crop genera found in this tribe include wheat (see wheat taxonomy), barley, and rye; crops in other genera include some for human consumption, and others used for animal feed or rangeland protection. Among the world's cultivated species, this tribe has some of the most complex genetic histories. An example is bread wheat, which contains the genomes of three species with only one being a wheat Triticum species. Seed storage proteins in the Triticeae are implicated in various food allergies and intolerances.
Genera recognized in Triticeae according to Robert Soreng et al.: [1]
Various species are cultivated for pastoral purposes or to protect fallow land from opportunistic or invasive species
Many barley cultivars
Ryes
(Wheat)
This article is missing information about cladogram of the nuclear genome sets; some more clear discussion separating nuclear and organellar topics.(March 2022) |
Genera & Species | 1st | 2nd | 3rd | ||
Triticum boeoticum | AA | ||||
Triticum monococcum | AMAM | ||||
Triticum urartu | AUAU | ||||
Aegilops speltoides var. speltoides | BB | ||||
Aegilops caudata | CC | ||||
Aegilops tauschii | DD | ||||
Lophopyrum elongatum | EE | ||||
Hordeum vulgare | HH | ||||
Thinopyrum bessarabicum | JJ | ||||
Aegilops comosa | MM | ||||
Aegilops uniaristata | NN | ||||
Henrardia persica | OO | ||||
Agropyrum cristatum | PP | ||||
Secale cereale | RR | ||||
Aegilops bicornis | SS | ||||
Amblyopyrum muticum | TT | ||||
Aegilops umbellulata | UU | ||||
Dasypyrum | VV | ||||
Psathyrostachys | NsNs | ||||
Pseudoroegneria | StSt | ||||
Triticum zhukovskyi | AA | AMAM | GG | ||
Triticum turgidum | AA | BB | |||
Triticum aestivum | AA | BB | DD | ||
Triticum timopheevii | AA | GG | |||
Aegilops cylindrica | CC | DD | |||
Stenostachys sp. | HH | WW | |||
Elmyus canadensis | HH | StSt | |||
Elmyus abolinii | YY | StSt | |||
Thinopyrum Vjd =(V/J/D) | JJ | StSt | VjdVjd | ||
Leymus tricoides | NsNs | XmXm |
Triticeae and its sister tribe Bromeae (bromes or cheat grasses) when joined form a sister clade with Poeae and Aveneae (Oats). Inter-generic gene flow characterized these taxa from the early stages. For example, Poeae and Aveneae share a mtDNA genetic marker with barley and 10 other members of Triticeae, whereas all 19 genera of Triticeae bear a wheat marker along with Bromeae. [4]
Genera within Triticeae contain diploid, allotetraploid and/or allohexaploid genomes, the capacity to form allopolyploid genomes varies within the tribe. In this tribe, the majority of diploid species tested are closely related to Aegilops, the more distal members (earliest branch points) include Hordeum (Barley), Eremian, Psathyrostachys. The broad distribution of cultivars within the Tribe and the properties of the proteins have implication in the treatment of certain digestive diseases and autoimmune disorders.[ citation needed ]
One of the earliest branches in Triticeae, to Pseudoroegeneria, produces the genome StSt and another Hordeum then genome = HH. Allotetraploid combinations of Pseudoroegeneria and Hordeum and are seen in Elmyus (HHStSt), [5] but also shows introgression from Australian and Agropyron wheatgrasses. [6] Elymus contains mostly Pseudoroegeneria mtDNA. [7]
Many genera and species of Triticeae are allopolyploids, having more chromosomes than seen in typical diploids. Typical allopolyploids are tetraploid or hexaploid, XXYY or XXYYZZ. The creation of polyploid species results from natural random events tolerated by polyploid-capable plants. Natural allopolyploid plants may have selective advantages and some may permit the recombination of distantly related genetic material. Poulard wheat is an example of a stable allotetraploid wheat.[ citation needed ]
The Secale (domesticated rye) may be a very early branch from the goat grass clad (or goat grasses are a branch of early rye grasses), as branch these are almost contemporary with the branching between monoploid wheat and Aegilops tauschii. Studies in Anatolia now suggest Rye ( Secale ) was cultivated, but not domesticated, prior to the holocene and to evidence for the cultivation of wheat. As climate changed the favorability of Secale declined. At that time other strains of barley and wheat may have been cultivated, but humans did little to change them.[ citation needed ]
Aegilops appears to be basal to several taxa such as Triticum, Amblyopyrum, and Crithopsis. Certain species such as Aegilops speltoides could potentially represent core variants of the taxa. The generic placement may be more a matter of nomenclature. Genera Aegilops and Triticum are very closely related; as the adjacent image illustrates, the Aegilops species occupy most of the basal branch points in bread wheat evolution indicating that genus Triticum evolved from Aegilops after an estimated 4 million years ago. [8] The divergence of the genomes is followed by allotetraploidization of a speltoid goatgrass x basal wheat species Triticum boeoticum with strains in the middle eastern region giving rise to cultivated emmer wheat. [9]
Hybridization of tetraploid wheat with Ae. tauschii produced a hulled wheat similar to spelt, suggesting T. spelta is basal. The tauschii species can be subdivided into subspecies tauschii (eastern Turkey to China or Pakistan) and strangulata (Caucasus to S. Caspian, N. Iran). The D genome of bread wheat is closer to A.t. strangulata than A.t. tauschii. It is suggested that Ae. tauschii underwent rapid selective evolution prior to combining with tetraploid wheat.[ citation needed ]
Intense use of wild Triticeae can be seen in the Levant as early as 23,000 years ago. [10] This site, Ohala II (Israel), also shows that Triticeae grains were processed and cooked. [11] Many cultivars appear to have been domesticated in the region of the upper Fertile Crescent, Levant and central Anatolia. [12] [13] More recent evidence suggests that cultivation of wheat from emmer's wheat required a longer period with wild seeding maintaining a presence in archaeological finds. [14]
Triticeae has a pastoral component that some contend goes back to the Neolithic period and is referred to as the Garden Hunting Hypothesis. In this hypothesis grains could be planted or shared for the purpose of attracting game animals so that they could be hunted close to settlements.[ citation needed ]
Today, rye and other Triticeae cultivars are used to graze animals, particularly cattle. Rye grasses in the New World have been used selectively as fodder, but also to protect grasslands without the introduction of invasive Old World species.[ citation needed ]
Glutens (storage proteins) in the Triticeae tribe have been linked to gluten-sensitive diseases. While it was once believed that oats carried similar potentials, recent studies indicate that most oat sensitivity is the result of contamination.[ citation needed ] Triticeae glutens studies are important in determining the links between gluten and gastrointestinal, allergic, and autoimmune diseases. [15] Some of the recently discovered biochemical and immunochemical properties of these proteins suggest they evolved for protection against dedicated or continuous consumption by mammalian seed-eaters. [16] [17] One recent publication even raises doubts about wheat's safety for anyone to eat. [18] Overlapping properties with regard to food preparation[ clarification needed ] have made these proteins much more useful as cereal cultivars, and a balanced perspective suggests a variable tolerance to Triticeae glutens reflects early childhood environment and genetic predisposition. [19] [20] [21] [22]
Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus Triticum ; the most widely grown is common wheat. The archaeological record suggests that wheat was first cultivated in the regions of the Fertile Crescent around 9600 BC. Botanically, the wheat kernel is a caryopsis, a type of fruit.
Rye is a grass grown extensively as a grain, a cover crop and a forage crop. It is a member of the wheat tribe (Triticeae) and is closely related to both wheat and barley. Rye grain is used for flour, bread, beer, crispbread, some whiskeys, some vodkas, and animal fodder. It can also be eaten whole, either as boiled rye berries or by being rolled, similar to rolled oats.
Triticale is a hybrid of wheat (Triticum) and rye (Secale) first bred in laboratories during the late 19th century in Scotland and Germany. Commercially available triticale is almost always a second-generation hybrid, i.e., a cross between two kinds of primary (first-cross) triticales. As a rule, triticale combines the yield potential and grain quality of wheat with the disease and environmental tolerance of rye. Only recently has it been developed into a commercially viable crop. Depending on the cultivar, triticale can more or less resemble either of its parents. It is grown mostly for forage or fodder, although some triticale-based foods can be purchased at health food stores and can be found in some breakfast cereals.
Secale is a genus of the grass tribe Triticeae, which is related to barley (Hordeum) and wheat (Triticum). The genus includes cultivated species such as rye as well as weedy and wild rye species. The best-known species of the genus is the cultivated rye, S. cereale, which is grown as a grain and forage crop. Wild and weedy rye species help provide a huge gene pool that can be used for improvement of the cultivated rye.
Emmer wheat or hulled wheat is a type of awned wheat. Emmer is a tetraploid. The domesticated types are Triticum turgidum subsp. dicoccum and T. t. conv. durum. The wild plant is called T. t. subsp. dicoccoides. The principal difference between the wild and the domestic forms is that the ripened seed head of the wild plant shatters and scatters the seed onto the ground, while in the domesticated emmer, the seed head remains intact, thus making it easier for humans to harvest the grain.
Durum wheat, also called pasta wheat or macaroni wheat, is a tetraploid species of wheat. It is the second most cultivated species of wheat after common wheat, although it represents only 5% to 8% of global wheat production. It was developed by artificial selection of the domesticated emmer wheat strains formerly grown in Central Europe and the Near East around 7000 BC, which developed a naked, free-threshing form. Like emmer, durum wheat is awned. It is the predominant wheat that grows in the Middle East.
Spelt, also known as dinkel wheat or hulled wheat, is a species of wheat that has been cultivated since approximately 5000 BCE.
Khorasan wheat or Oriental wheat is a tetraploid wheat species. The grain is twice the size of modern-day wheat, and has a rich, nutty flavor.
Gliadin is a class of proteins present in wheat and several other cereals within the grass genus Triticum. Gliadins, which are a component of gluten, are essential for giving bread the ability to rise properly during baking. Gliadins and glutenins are the two main components of the gluten fraction of the wheat seed. This gluten is found in products such as wheat flour. Gluten is split about evenly between the gliadins and glutenins, although there are variations found in different sources.
Aegilops is a genus of Eurasian and North American plants in the grass family, Poaceae. They are known generally as goatgrasses. Some species are known as invasive weeds in parts of North America.
Common wheat, also known as bread wheat, is a cultivated wheat species. About 95% of wheat produced worldwide is common wheat; it is the most widely grown of all crops and the cereal with the highest monetary yield.
During 10,000 years of cultivation, numerous forms of wheat, many of them hybrids, have developed under a combination of artificial and natural selection. This diversity has led to much confusion in the naming of wheats. Genetic and morphological characteristics of wheat influence its classification; many common and botanical names of wheat are in current use.
Wheat allergy is an allergy to wheat which typically presents itself as a food allergy, but can also be a contact allergy resulting from occupational exposure. Like all allergies, wheat allergy involves immunoglobulin E and mast cell response. Typically the allergy is limited to the seed storage proteins of wheat. Some reactions are restricted to wheat proteins, while others can react across many varieties of seeds and other plant tissues. Wheat allergy is rare. Prevalence in adults was found to be 0.21% in a 2012 study in Japan.
Aegilops tauschii, the Tausch's goatgrass or rough-spike hard grass, is an annual grass species. It is native to Crimea, the Caucasus region, western and Central Asia, Afghanistan, Pakistan, the western Himalaya, and parts of China, and has been introduced to other locales, including California.
Tapesia yallundae is the causal agent for a variety of cereal and forage grass diseases. The anamorph of T. yallundae is the W-type strain of Pseudocercosporella herpotrichoides. The R-type strain of Pseudocercosporella herpotrichoides is now known as Tapesia acuformis.
Gluten is the seed storage protein in mature wheat seeds. It is the sticky substance in bread wheat which allows dough to rise and retain its shape during baking. The same, or very similar, proteins are also found in related grasses within the tribe Triticeae. Seed glutens of some non-Triticeae plants have similar properties, but none can perform on a par with those of the Triticeae taxa, particularly the Triticum species. What distinguishes bread wheat from these other grass seeds is the quantity of these proteins and the level of subcomponents, with bread wheat having the highest protein content and a complex mixture of proteins derived from three grass species.
Anti-gliadin antibodies are produced in response to gliadin, a prolamin found in wheat. In bread wheat it is encoded by three different alleles, AA, BB, and DD. These alleles can produce slightly different gliadins, which can cause the body to produce different antibodies. Some of these antibodies can detect proteins in specific grass taxa such as Triticeae, while others react sporadically with certain species in those taxa, or over many taxonomically defined grass tribes.
Glutelins are a class of prolamin proteins found in the endosperm of certain seeds of the grass family. They constitute a major component of the protein composite collectively referred to as gluten. Glutenin is the most common glutelin, as it is found in wheat and is responsible for some of the refined baking properties in bread wheat. The glutelins of barley and rye have also been identified. Glutelins are the primary protein form of energy storage in the endosperm of rice grains.
Barley, a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains; it was domesticated in the Fertile Crescent around 9,000 BC, giving it nonshattering spikelets and making it much easier to harvest. Its use then spread throughout Eurasia by 2,000 BC. Barley prefers relatively low temperatures to grow, and well-drained soil. It is relatively tolerant of drought and soil salinity, but is less winter-hardy than wheat or rye.
Triticum carthlicum Nevski, 1934, the Persian wheat, is a wheat with a tetraploid genome.
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