Triticeae is a botanical

tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide usage of the term in English is in the discipline of anthropology. This definition is contested, in part due to confl ...

within the subfamily

Pooideae The Pooideae are the largest subfamily of the grass family Poaceae, with about 4,000 species in 15 tribes and roughly 200 genera. They include some major cereals such as wheat, barley, oat, rye and many lawn and pasture grasses. They are often ...

of grasses that includes genera with many domesticated species. Major crop genera found in this tribe include

wheat 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 (''T. aestivum''). The archaeologi ...

(see wheat taxonomy),

barley Barley (''Hordeum vulgare''), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains, particularly in Eurasia as early as 10,000 years ago. Globally 70% of barley p ...

, 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 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 (''T. aestivum''). The archaeological ...

'' species. Seed storage proteins in the Triticeae are implicated in various

food allergies A food allergy is an abnormal immune response to food. The symptoms of the allergic reaction may range from mild to severe. They may include itchiness, swelling of the tongue, vomiting, diarrhea, hives, trouble breathing, or low blood pressur ...

and intolerances.

Genera of Triticeae

Genera recognized in Triticeae according to Robert Soreng et al.: *'' Aegilops'' *''

Agropyron ''Agropyron'' is a genus of Eurasian plants in the grass family), native to Europe and Asia but widely naturalized in North America. Species in the genus are commonly referred to as wheatgrass. ; Species * ''Agropyron badamense'' - Tajikis ...

'' *'' Amblyopyrum'' *'' Anthosachne'' *'' Australopyrum'' *'' Connorochloa'' *''

Crithopsis ''Crithopsis'' is a genus of plants in the grass family, native to the Mediterranean and nearby areas. ;Species The only known species is ''Crithopsis delileana,'' native to Morocco, Tunisia, Libya, Egypt, Crete, Turkey, Lebanon, Syria, Israel, ...

'' *'' Dasypyrum'' *'' Douglasdeweya'' *'' Elymus'' (syn. '' Campeiostachys'', ''

Elytrigia ''Elytrigia'' is a genus of about 20–40 species of grasses, native to temperate regions of the Old World, in Europe, Asia, and northwest Africa. The species are sometimes included in the related genera ''Agropyron'' or '' Elymus'', while spec ...

'', '' Hystrix'', '' Roegneria'', '' Sitanion'') *''

Eremopyrum ''Eremopyrum'' is a genus Eurasian and North African plants in the grass family. One species, ''Eremopyrum triticeum'' has become widely established as a weed in parts of North America. All the species are annuals with a dense, 2-sided, spikelik ...

'' *'' Festucopsis'' *'' Henrardia'' *'' Heteranthelium'' *'' Hordelymus'' *''

Hordeum ''Hordeum'' is a genus of annual and perennial plants in the grass family. They are native throughout the temperate regions of Africa, Eurasia, and the Americas. One species, ''Hordeum vulgare'' ( barley), has become of major commercial importa ...

'' (syn. '' Critesion'') *'' Kengyilia'' *'' Leymus'' (syn. '' Aneurolepidium'', '' Eremium'', '' Macrohystrix'', '' Microhystrix'') *''

Pascopyrum ''Pascopyrum'' is a monotypic genus of grass containing the sole species ''Pascopyrum smithii'', which is known by the common names western wheatgrass and red-joint wheatgrass, after the red coloration of the nodes. It is native to North America. ...

'' *'' Peridictyon'' *'' Psathyrostachys'' *''

Pseudoroegneria ''Elymus'' is a genus of perennial plants with approximately 150 species in the grass family, related to rye, wheat, and other widely grown cereal grains. ''Elymus'' is a cosmopolitan genus, represented by species across all continents of the w ...

'' *''

Secale ''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 (''Secale cereale'') as well as weedy and wild rye species. The most well k ...

'' *'' Stenostachys'' *''

Taeniatherum ''Taeniatherum'' is a genus of Eurasian and North African plants in the grass family known by the common name medusahead. The only recognized species is ''Taeniatherum caput-medusae'' and is native to southern and central Europe (from Portugal ...

'' *''

Thinopyrum ''Thinopyrum'' is a genus of Eurasian and African plants in the grass family. Species The following species are recognised in the genus ''Thinopyrum'': *'' Thinopyrum acutum'' (DC.) Banfi - Europe, Turkey *'' Thinopyrum bessarabicum'' (Savul. & ...

'' *''

Cultivated or edible species

''Aegilops''

*Various species (rarely identifiable to species in archaeological material) occur in pre-agrarian archaeobotanical remains from Near Eastern sites. Their edible grains were doubtless harvested as wild food resources. * '' speltoides''
ancient food grain
putative source of B genome in bread wheat and G genome in ''T. timopheevii'' * '' tauschii'' - Source of D genome in wheat

''Amblyopyrum''

* ''muticum'' - Source of T genome.

''Elymus''

Various species are cultivated for pastoral purposes or to protect fallow land from opportunistic or invasive species * '' canadensis''
edible, bread-flour capable, fiddly seeds
* '' trachycaulus''
pastoral cultivar

''Hordeum''

Many barley cultivars * '' vulgare'' - common barley (6 subspecies, ~100 cultivars) * ''bulbosum''
edible seeds
* '' murinum'' (mouse barley)
cooked as piñole, bread-flour capable
medicinal: diuretic.

''Leymus''

* '' arenarius'' (Lyme grass)
bread-flour capable, possible food additive
* '' racemosus'' (Volga Wild Rye)
drought tolerant cereal, used in Russia
* '' condensatus'' (Giant Wild Rye)
Edible seeds, harvesting problematic small seeds
* '' triticoides'' (Squaw grass)
used in North America, seed hairs must be singed

''Secale''

Ryes * '' cereale'' (Cereal Rye) - Livestock feed and sour dough bread - 6 subspecies. * ''cornutum'' (spurred rye) - herbal medicine:

ergot Ergot ( ) or ergot fungi refers to a group of fungi of the genus ''Claviceps''. The most prominent member of this group is '' Claviceps purpurea'' ("rye ergot fungus"). This fungus grows on rye and related plants, and produces alkaloids that c ...

(ergot of spurred rye) at very low doses; dangerously toxic as food. * ''strictum''
actively cultivated
* ''sylvestre'' - (Tibetan Rye)
actively cultivated
in Tibet and China highlands. * ''vavilovii'' (Armenian Wild Rye)
edible seeds, thickener

''Triticum''

(Wheat) * '' aestivum'' (bread wheat) - (AABBDD Genome) ** ''compactum'' (club wheat) ** ''macha'' (hulled) ** ''spelta'' (hulled,

spelt Spelt (''Triticum spelta''), also known as dinkel wheat or hulled wheat, is a species of wheat that has been cultivated since approximately 5000 BC. Spelt was an important staple food in parts of Europe from the Bronze Age to medieval times. N ...

) ** ''sphaerococcum'' (shot wheat) * ''monococcum'' (Einkorn wheat) (A Genome) * '' timopheevii'' (Sanduri wheat) * ''turgidum'' (poulard wheat) (AABB Genome) ** '' carthlicum'' (Persian black wheat) ** ''dicoccoides'' (wild emmer wheat) ** '' dicoccum'' (cultivated emmer wheat) - used to make Farro ** ''

durum Durum wheat (), also called pasta wheat or macaroni wheat (''Triticum durum'' or ''Triticum turgidum'' subsp. ''durum''), is a tetraploid species of wheat. It is the second most cultivated species of wheat after common wheat, although it repres ...

'' (durum wheat) ** ''paleocolchicum'' ** '' polonicum'' (Polish wheat) ** '' turanicum''

Genetics

Triticeae and its sister tribe ''Bromeae'' (bromes or cheat grasses) when joined form a sister clade with ''

Poeae The Poeae are the largest tribe of the grasses, with around 2,500 species in 121 genera. The tribe includes many lawn and pasture grasses. Taxonomy Two separate tribes, Poeae and Aveneae, used to be distinguished based on morphology, but phylog ...

'' and ''Aveneae'' ( Oats). Inter-generic gene flow characterized these taxa from the early stages. For example, Poeae and Aveneae share a mtDNA

genetic marker A genetic marker is a gene or DNA sequence with a known location on a chromosome that can be used to identify individuals or species. It can be described as a variation (which may arise due to mutation or alteration in the genomic loci) that can be ...

with barley and 10 other members of Triticeae, whereas all 19 genera of Triticeae bear a wheat marker along with Bromeae. Genera within Triticeae contain

diploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectiv ...

allotetraploid Polyploidy is a condition in which the cells of an organism have more than one pair of ( homologous) chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set contains ...

and/or

allohexaploid Polyploidy is a condition in which the cells of an organism have more than one pair of ( homologous) chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set contains ...

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.

Evolution of the tribe

One of the earliest branches in Triticeae, to ''Pseudoroegeneria'', produces the genome StSt and another ''Hordeum'' then genome = HH. Allotetraploid combinations of ''Pseudoroegeneria'' and ''

'' and are seen in ''Elmyus'' (HHStSt), but also shows introgression from Australian and Agropyron wheatgrasses. Elymus contains mostly ''Pseudoroegeneria'' mtDNA. 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. 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 (''

'') was cultivated, but not domesticated, prior to the

holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...

and to evidence for the cultivation of wheat. As climate changed the favorablitiy of ''Secale'' declined. At that time other strains of barley and wheat may have been cultivated, but humans did little to change them.

Goat grasses and the evolution of bread wheat

Tetraploidization in wild emmer wheat

''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. 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.

Hexaploidization of tetraploid wheat

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.

Wild Triticeae use by humans

Intense use of wild Triticeae can be seen in the Levant as early as 23,000 years ago. This site, Ohala II (Israel), also shows that Triticeae grains were processed and cooked. Many cultivars appear to have been domesticated in the region of the upper Fertile Crescent, Levant and central Anatolia. 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.

Pastoral grasses

Triticeae has a

pastoral A pastoral lifestyle is that of shepherds herding livestock around open areas of land according to seasons and the changing availability of water and pasture. It lends its name to a genre of literature, art, and music (pastorale) that depict ...

component that some contend goes back to the Neolithic period and is referred to as th
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. 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.

Triticeae and health

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.

Triticeae glutens Gluten is the seed storage protein in mature wheat seeds (and in the seeds of closely related species). It is the sticky substance in bread wheat which allows dough to rise and retain its shape during baking. The same, or very similar, protein ...

studies are important in determining the links between gluten and gastrointestinal, allergic, and autoimmune diseases. 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. One recent publication even raises doubts about wheat's safety for anyone to eat. Overlapping properties with regard to food preparation 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.

References

External links

Pubmed:Triticeae

Database of Edible Seed Plants

- An excellent resource for the ancestral genetics of Triticeae.

Triticeae germplasm
{{Taxonbar, from=Q148694 Pooideae Cereals Poaceae tribes Taxa named by Carl Linnaeus