Wheat Taxonomy

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Effects of crop processing on glume wheats and free-threshing cereals: the free-threshing traits first appeared in cultivated wheats such as cultivated einkorn.

đŸŒŸ This page is an ongoing research dedicated to wheat and its taxonomy. It is meant to be use as a background of the art project ”Improvised wheat”, a collaborative project involving The Soft Protest Digest and French artist RaphaĂ«l Bastide.

Taxonomic table of the wheat family

An overview of the different taxonomics of wheat relatives

Taxonomy from genome and evolutive pattern

GENOTYPE
Common name(s) (english/french) Name: species (latin) Sub-species (latin) Genome Number of sets of chromosomes Evolutive pattern
A B G D S diploid tetraploid hexaploid wild domesticated
natural selection natural hybridation human selection human hybridation F1 hybrid (breeding) GMO (not cultivated)
Goatgrass / Égilope faux-Ă©peautre Aegilops speltoides (B) (G) S X X
Tausch’s goatgrass / Égilope de Tausch Aegilops tauschii D X X
Einkorn wheat (wild) / Engrain sauvage Triticum boeoticum Ab X X
Einkorn wheat (cultivated) / Engrain, Petit-Ă©peautre Triticum monococcum Am X X
(non-threshing)
Red wild einkorn wheat / (Blé rouge sauvage) Triticum urartu Au X X
Armenian, Araratian wild emmer / (Amidonnier sauvage d’ArmĂ©nie) Triticum araraticum Au G X X
Zanduri wheat / Blé zanduri Triticum timopheevii Au G X X
Wild emmer wheat / Amidonnier sauvage (Tetraploid wheat) Triticum turgidum didoccoides Au B X X
River wheat, Cone wheat / Blé poulard (blanc lisse) turgidum Au B X X
Emmer wheat (white) / Amidonnier blanc, Épeautre de Tartarie didoccum amyleum Au B X X
Emmer wheat (black) / Amidonnier noir, Noir barbu didoccum Au B X X
Durum wheat / Blé dur durum Au B X X
(naked seed)
Zhukovsky’s wheat / BlĂ© de Joukovsky Triticum zhukovskyi AuAm G X X
Common wheat, Bread wheat / Blé tendre, Froment Triticum aestivum aestivum Au B D X X
Spelt, hulled wheat / Épeautre, BlĂ© des Gaulois / Farro (IT) spelta Au B D X X

Taxonomy from morphologic aspect

PHENOTYPE
Common name(s) (english/french) Grains Straw Spikelets Color (when mature)
free-threshing non-brittle rachis (dehusking) hulled (keeps glume) naked (looses glume) single double tall (70-150cm) semi-dwarf (40-60cm) dwarf (20-30cm) with awn (bearded) without awn seed, grain, caryopse ear, blades, spike straw, stem, culm
yellow white red black yellow white red yellow white red
Goatgrass / Égilope faux-Ă©peautre X X X X X X X X
Tausch’s goatgrass / Égilope de Tausch X X X X X X X
(green)
X
(green)
Einkorn wheat (wild) / Engrain sauvage X X X (X) X X X X
(orange)
X
Einkorn wheat (cultivated) / Engrain, Petit-Ă©peautre X X (X) X X X X
(orange)
X
Red wild einkorn wheat / (Blé rouge sauvage) X X (X) X X X X
(green)
X
Armenian, Araratian wild emmer / (Amidonnier sauvage d’ArmĂ©nie) X X (X) X X X X X
Zanduri wheat / Blé zanduri X X X (X) X X X X X
Wild emmer wheat / Amidonnier sauvage (Tetraploid wheat) X X X X X X X X
River wheat, Cone wheat / Blé poulard (blanc lisse) X X X X X X X X X
Emmer wheat (white) / Amidonnier blanc, Épeautre de Tartarie X X X X X
(short)
X X X
Emmer wheat (black) / Amidonnier noir, Noir barbu X X X X X X X X
Durum wheat / Blé dur X X X X X X X
(translucent)
X X
Zhukovsky’s wheat / BlĂ© de Joukovsky X X X X X X X X
Common wheat, Bread wheat / Blé tendre, Froment X X X X X X
(Rht genes)
X Colour varies with common wheat’s numerous varieties
Spelt, hulled wheat / Épeautre, BlĂ© des Gaulois / Farro (IT) X X X X X X X X

Possible datas to draw a portrait of wheat

An overview of grains difference from 6 species.

Most of these factors are related to taxonomy, and a lot of different models have existed through time, but DNA sequencing did not changed much of wheats’ taxonomy.

  • Worldwide production of wheat
  • Species of wheat:
    • diploid, tetraploid, hexaploid (chromosomes organisation)
    • season (often used for its taxonomy)
    • evolutive pattern (natural/artificial selection, hybridation, F1[1], GMOs[2], etc.)
  • Chemical composition of wheat:
    • proteins (gluten)
    • fat
    • amino acids
    • carbohydrates
    • vitamins
    • minerals
    • water content
  • Morphology of wheat:
    • color (ear, seed, straw)
    • hulled / naked (free-threshing)
    • dwarfed / semi-dwarfed / tall (height)[3]
    • bearded spikelets

Gallery

Aegilops species

Triticum boeoticum

Triticum monococcum

Triticum araraticum

Triticum turgidum

Triticum zhukovskyi

Triticum aestivum

Set of references

Genomic classification of wheat

Source: https://en.wikipedia.org/wiki/Taxonomy_of_wheat#Table_of_wheat_species

The observation of chromosome behaviour during meiosis, and the results of hybridisation experiments, have shown that wheat genomes (complete complements of genetic matter) can be grouped into distinctive types. Each type has been given a name, e.g. B or D. Grasses sharing the same genome will be more-or-less interfertile, and might be treated by botanists as one species. Identification of genome types is obviously a valuable tool in investigating hybridisation. For example, if two diploid plants hybridise to form a new polyploid form (an allopolyploid), the two original genomes will be present in the new form. Many thousands of years after the original hybridisation event, identification of the component genomes will allow identification of the original parent species.

In Triticum, five genomes, all originally found in diploid species, have been identified:

  • Am â€“ present in wild einkorn (T. boeoticum).
  • A – present in T. urartu (closely related to T. boeoticum but not interfertile).
  • B – present in most tetraploid wheats. Source not identified, but similar to Ae. speltoides.
  • G – present in timopheevi group of wheats. Source not identified, but similar to Ae. speltoides.
  • D – present in Ae. tauschii, and thus in all hexaploid wheats.

The genetic approach to wheat taxonomy (see below) takes the genome composition as defining each species. As there are five known combinations in Triticum this translates into five super species:

  • Am T. monococcum
  • Au T. urartu
  • BAu T. turgidum
  • GAm T. timopheevi
  • BAuD T. aestivum

Polyploidy definition

Source: https://en.wikipedia.org/wiki/Polyploidy#Polyploid_types

Polyploidy is a condition in which the cells of an organism have more than two paired (homologous) sets of chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two sets of chromosomes—one set inherited from each parent. However, some organisms are polyploid.

The diverse polyploidies and species related to wheat:

  • haploid (one set; 1x) not present in wheats.
  • diploid (two sets; 2x) as T. urartu or Ae. speltoides.
  • triploid (three sets; 3x) not present in wheats.
  • tetraploid (four sets; 4x) as T. dicoccum or T. durum.
  • pentaploid (five sets; 5x) not present in wheats.
  • hexaploid (six sets; 6x) as T. aestivum and T. spelta.

Wheat genomic/molecular/phylogenic taxonomy

  1. Source: https://www.researchgate.net/profile/N-Goncharov/publication/225341394_Genus_Triticum_L_taxonomy_The_present_and_the_future/links/5524e3210cf2caf11bfce76c/Genus-Triticum-L-taxonomy-The-present-and-the-future.pdf
  2. Source: http://ressources.semencespaysannes.org/docs/triticum.pdf
  3. Source: https://www.researchgate.net/publication/243962682_Origin_and_taxonomy_of_wheat_in_the_light_of_recent_research
  4. Source: https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=42236#null

About wheat breeding

Source: https://www.youtube.com/watch?v=82Xt7RoW9uc

Wheat dwarfing and Rht genes

Source: https://academic.oup.com/jhered/article/96/4/455/2187931

Wheat pictures

  1. Source: https://www.alanbuckingham.com/
  2. Source (for grains color): https://www.sciencedirect.com/science/article/abs/pii/S0733521016301540

Notes

  1. ↑ F1 hybrids were also invented for the productive goals of the Green Revolution. Two selected homozygous “pure” plants (same genome from father + from mother through self-reproduction) with good characteristics are multiplied, thus obtaining F1 heterozygous offsprings (entire genome from father + from mother). The idea is to get the most homogeneous fields with the best individual genome of 2 varieties of wheat, with as few variations as possible. Thus, the next generations of F1s that could naturally occur cannot keep its homogeneous characteristics in time, because of wild heterozygous reproduction, self-reproduction mixing its genes, or mutations. That’s why farmers will have to buy seeds to cultivate it. This F1 plants can also be used by self-reproduction to get a renewed variety where some will be selected and kept.
  2. ↑ GMOs have been experimented with wheat but never reached a commercial use.
  3. ↑ During the Green Revolution in the mid 20th century, the emergence of synthetic fertilisers derived from mining forced a selection of wheat varieties with the goal to lower its height. With these new fertilisers, original wheat varieties of normal size would fall down the grown (lodging) and spoil or become impossible to harvest. That’s why most modern wheat are dwarfed thanks to reduced-height genes (Rht) found in the Japanese wheat variety Akakomugi.