Genome Facts

The cereal known as wheat comes from several closely related species. Four of these species are cultivated: einkorn (Triticum monococcum ssp. monococcum), emmer (T. turgidum ssp. durum), timopheevii (T. timopheevii ssp. timopheevii) and common or bread wheat (T. aestivum).

Common/bread wheat(Triticum aestivum) is a disomic allohexaploid (AABBDD genomes). It arose from the convergence of three diploid ancestors that have diverged from a common ancestor and coevolved some 2.5 to 4.5 million years ago. Approximately 0.5 million years ago, the diploid wheats T. urartu (AA genomes) and Aegilops speltoides (SS genomes, most closely related to the B genome) hybridized to form the tetraploid wheat T. turgidum (AABB), which includes durum wheat. About 8,000 years ago T. turgidum hybridized with the wild diploid goatgrass Aegilops tauschii (DD genomes) to form bread wheat. Mapping studies using cDNAs and ESTs as RFLP probes indicate that the three genomes of hexaploid wheat carry, in general, the same genes at the same relative positions along homoeologous chromosomes, aside from a few well-known large translocations, and probably many other still unknown local rearrangements.

Wheat nucleotide sequences in GenBank

GenBank division	Entries	Total bp
dbEST	880,515	339,239,649
dbGSS	32,581	6,271,668
dbHTG	80	1,552,156
dbPLN	7,843	10,035,245
dbSTS	658	311,744
WGS	5,055	3,691,256
Total	926,732	361,101,718

Wheat related publications in PubMed

Publications in PubMed...	Total
...with wheat in title	9,256
...with wheat in abstract	23,116

TIGR Annotated Genes

Wheat Gene Features	Total
Total BAC number	67
Total gene models	582
Average gene size (bp)	2,220
Average exon number	2.8
Average exon length (bp)	318
Average exon GC content (%)	55.9
Average intron number	1.8
Average intron length (bp)	694
Average intron GC content (%)	43.9

Genes from TIGR Annotated Wheat BACs

	Gene number	Percentage	Ave. gene size (bp)
Known/Putative	190	32.6	2721
Expressed	25	4.3	3368
Conserved Hypothetical	32	5.5	1871
Hypothetical	335	57.6	1884