| WHEAT CULTIVAR | PLOIDY LEVEL | GENOMES PRESENT | ANCESTRY | KEY NOTES |
Einkorn wheat (Triticum monococcum) | Diploid | AA 14 (2x) | Diploid ancestral wheat; progenitor of the A genome in polyploids | Hulled, ancient diploid wheat, earliest domesticated wheat |
Emmer wheat (Triticum turgidum ssp. dicoccum) | Tetraploid | AABB 28 (4x) | Tetraploid; formed by hybridization of einkorn (AA) and wild B genome donor | Hulled, foundational tetraploid wheat; ancestor of durum and others |
Durum wheat (Triticum turgidum ssp. Durum) | Tetraploid | AABB 28 (4x) | Free-threshing descendant of emmer wheat | Widely cultivated pasta wheat; domesticated form |
Khorasan wheat (Triticum turgidum ssp. turanicum) | Tetraploid | AABB 28 (4x) | Hybrid of durum wheat and Triticum polonicum (both AABB) | Larger grains; hybrid form within tetraploids |
Spelt wheat (Triticum spelta) | Hexaploid | AABBDD 42 (6x) | Hexaploid; hybrid of emmer wheat (AABB) and goatgrass (DD) | Hulled bread wheat; ancestral to modern bread wheat |
Common bread wheat (Triticum aestivum) | Hexaploid | AABBDD 42 (6x) | Hexaploid; evolved from spelt and related hexaploids | Free-threshing, most widely cultivated wheat worldwide |
Summary lineages:
Diploid to tetraploid:
Einkorn (AA, 2n=14) + wild B genome → Emmer wheat (AABB, 2n=28)
Tetraploid derivatives:
Emmer → Durum (free-threshing selection)
Durum + Triticum polonicum → Khorasan (hybrid)
Tetraploid to hexaploid:
Emmer (AABB) + Goatgrass (DD) → Spelt (AABBDD, 2n=42) → Bread wheat (AABBDD)
Key Highlights
- Emmer wheat is the genetic ancestor, the "father" of durum wheat and the broader tetraploid wheat group.
- Durum wheat is a free-threshing domesticated derivative of emmer.
- Khorasan wheat is a natural hybrid between durum wheat and Triticum polonicum, making it closely related but genetically distinct.
- All three are tetraploid wheats with 28 chromosomes, sharing the AABB genome, with emmer being the oldest and foundational species, durum the most widely cultivated descendant, and Khorasan an ancient hybrid derivative.
🧬 Wheat Genomes vs. Dough Performance
| Wheat Type | Genomes Present | Key Gluten Genes | Dough Properties | Typical Use |
|---|---|---|---|---|
| Einkorn | AA | Glu-A1 only | Weak gluten, low elasticity | Crackers, flatbreads, ancient grain products |
| Emmer/Durum/Khorasan | AABB | Glu-A1, Glu-B1 | Strong but inelastic gluten | Pasta, couscous, dense breads |
| Bread Wheat/Spelt | AABBDD | Glu-A1, Glu-B1, Glu-D1 | Balanced strength and extensibility | Leavened bread, noodles, pastries |
🧪 Impact of Glu-D1 (D Genome) on Dough & Flour
| Trait | Without D Genome (AABB) | With D Genome (AABBDD) |
|---|---|---|
| Gluten Elasticity | Strong, but stiff | Balanced elasticity and strength |
| Loaf Volume | Moderate to low | High, better gas retention |
| Mixing Characteristics | Short development time | Longer stability, higher tolerance |
| Cookie Spread | Smaller diameter | Improved diameter and texture |
| Milling Efficiency | Lower flour yield | Higher break flour yield |
- The Glu-D1 gene on chromosome 1D makes proteins like Dx5+Dy10 and Dx2+Dy12 that build gluten networks, giving dough stretch and structure.
- Without it, you get strong but brittle dough—perfect for pasta, but tricky for fluffy bread.
I pointed AI at this paper https://pmc.ncbi.nlm.nih.gov/articles/PMC7316921/ and asked it to provide a summary.
🍞 Durum Wheat and Baking Properties – Key Insights
- Gluten Composition: Durum wheat has strong gluten but lacks the extensibility provided by the D genome (specifically the Glu-D1 locus), making it less suitable for leavened bread.
- Protein Quality: Its glutenin and gliadin profile favours firmness and strength, ideal for pasta but resulting in low loaf volume and poor gas retention in bread dough.
- Water Absorption: Durum flour tends to absorb more water, which affects dough handling and mixing characteristics.
- Dough Rheology: Durum dough shows short development time, low stability, and high resistance to extension, leading to stiffer, less elastic dough.
- Starch Damage and Milling: Durum’s hard kernel structure causes more starch damage during milling, influencing flour performance in baked goods.
- Soft Kernel Durum Innovations: Breeding efforts to introduce soft kernel traits (via D-genome introgression) have improved milling yield and cookie spread, enhancing its versatility.
- Synthetic Hexaploid Durum: Crossing durum with Aegilops tauschii (D genome donor) improves dough strength and bread-making potential by restoring missing glutenin subunits.
- End-Use Limitations: Traditional durum flour is best suited for pasta and flatbreads, while its limitations in extensibility and gas retention restrict its use in conventional bread baking.
The above is a collation of information I sourced with the assistance of AI.
Starting with something I read which said Durum wheat is without the D genome. And then a reminder that Durum wheat gluten suffers from being inelastic and poorly extensible.
Very interesting indeed. Thank you.
TomP
So, a human has only 4 chromosomes more than a piece of grass.
That explains a lot.
Thanks, this is just what I needed in my life! Great! :)