Wheat biosystematics

1. WHEAT BIOSYSTEMATICS
BY,
T.MITHRAA
2016601602

2. The genus Triticum
• Poaceae
• Highly inconsistent taxonomy
• Triticum and Aegilops separate genera
• Triticum sensu lato
– Includes Aegilops
• Triticum sensu stricto ~ 10 species
• Native to Mediterranean area
• Base n = 7

3. Domesticated Wheats
• Triticum monococcum L. (cultivated einkorn)
– T. boeoticum (wild einkorn)
– Diploid - AA
• Triticum dicoccum Schübl. (emmer wheat)
– T. dicoccoides (wild emmer)
– Tetraploid – AABB
• Triticum aestivum L. (bread or common wheat)
– Hexaploid - AABBDD
– T. dicoccoides (AABB) + Aegilops tauschii (DD)

5. Africa
ORIGIN OF WHEAT
Central Asia

6. CHROMOSOME NO. AND PLACE OF ORIGIN
Ploidy level Chromosome no. Place of origin
Diploid : 2n = 14 Asia minor
Tetraploid : 2n = 28 Abyssinia, North Africa
Hexaploid : 2n = 42 Central Asia

7. Ploidy
level
Species Common name Genome
Diploid
(2n=14)
T. boeticum
(T. aegilopoides)
T. monococcum
T. speltoides
T. tauschii
Wild einkorn
Einkorn (Culti)
Wild goat grass
Wild
AA
AA
BB
DD
Classification

8. Ploidy level Species Common name Genome
Tetraploid
(2n = 28)
T. dicoccoides
T. dicoccum
T. durum
T. persicum
T. turgidum
T. polonicum
T. timopheevi
Wild Emmer
Emmer (Culti)
Macaroni wheat (C)
Persian wheat (C)
Rivet wheat (C)
Polish wheat (C)
Timopheevi (W)
AABB
AABB
AABB
AABB
AABB
AABB
AABB
Classification

9. Ploidy level Species Common name Genome
Hexaploid
(2n=42)
T. aestivum
T. compactum
T. sphaerococcum
T. spelta
T. macha
Common /bread
Club wheat
Dwarf wheat
Spelt wheat
Macha wheat
AABBDD
AABBDD
AABBDD
AABBDD
AABBDD
Classification

10. T. boeoticum (T.aegilopoides)
(Wild einkorn) (AA)
Natural mutation and selection
T. monoccocum
Cultivated diploid
AA (2n = 14)
Origin of diploid wheat

11. T. monococcum x T. speltoides
AA BB
(2n = 14) (2n = 14)
F1 sterile (2n = 14) (AB)
Natural mutation and Doubling
T. dicoccoides (2n = 28)
Wild emmer AABB
By natural selection
T. dicoccum (Emmer wheat)
AABB (2n = 28) Cultivated
ORIGIN OF TETRAPLOID WHEAT

12. T.dicoccum x T. tauschii
AA BB DD
(2n = 28) (2n = 14)
F1
ABD (2n = 21) - Sterile
Natural doubling
T. aestivum
AABBDD (2n = 42)
(Cultivated)
Origin of hexaploid wheat

13. Evolution of hexaploid wheat
T. boeoticum x
T. speltoides
T. tauschii T. aestivum
T.dicoccoides
T. dicoccum

14. Salamini et al., 2002

15. The evolution of hexaploid bread wheat from its wild
relatives.
T. monococcum x T. speltoides
AA BB
(2n = 14) (2n = 14)
F1 sterile (2n = 14) (AB)
Doubling (2n =
28)
X Aegilops squarrosa
3x = 21
Doubling
6x = 42 AABBDD Hexaploid
wheat

16. 1. T. boeoticum (Wild Einkorn)
• Primitive type from which other species have evolved
• With one to two seeded spikelets.
• It is the ancestor for all the cultivated wheat
2.T.monococcum (Cultivated Einkorn)
• Primitive diploid form domesticated, evolved from
T. boeoticum by mutation and selection.
3.T.dicoccoides (Wild Emmer)
• Amphidiploid form from the hybridization of T. boeticum and T.
speltoides.
Related species of Triticum

17. 4.T.dicoccum (Cultivated Emmer)
• Developed thro’ natural selection
• The spikelets are two grained
• Grains retained within the glumes after threshing (speltoid).
• It is the oldest of the cultivated wheat.
5.T. durum (Macroni wheat)
Free threshing; wheat with naked grains
Important of the tetraploid wheats.
Grains contain high gluten.
•
Related species of Triticum

18. 6. T. speltoides (wild)
• Naturally cross pollinating
• Recognized donor of the B genome.
7. T. tauschii (wild)
• Source of D genome in the cultivated hexaploid wheat, which has high
adaptability.
Related species of Triticum

19. The cultivated wheat is classified into two
Types of wheat
Winter wheat
• Long duration
cultivated during
October – November to May - July.
Spring wheat
• short duration
cultivated during
March - May to August –September

20. THANK YOU