Types and rates of sequence evolution at the high-molecular-weight glutenin locus in hexaploid wheat and its ancestral genomes.
The Glu-1 locus, encoding the high-molecular-weight glutenin protein subunits, controls bread-making quality in hexaploid wheat (Triticum aestivum) and represents a recently evolved region unique to Triticeae genomes. To understand the molecular evolution of this locus region, three orthologous Glu-1 regions from the three subgenomes of a single hexaploid wheat species were sequenced, totaling 729 kb of sequence. Comparing each Glu-1 region with its corresponding homologous region from the D genome of diploid wheat, Aegilops tauschii, and the A and B genomes of tetraploid wheat, Triticum turgidum, revealed that, in addition to the conservation of microsynteny in the genic regions, sequences in the intergenic regions, composed of blocks of nested retroelements, are also generally conserved, although a few nonshared retroelements that differentiate the homologous Glu-1 regions were detected in each pair of the A and D genomes. Analysis of the indel frequency and the rate of nucleotide substitution, which represent the most frequent types of sequence changes in the Glu-1 regions, demonstrated that the two A genomes are significantly more divergent than the two B genomes, further supporting the hypothesis that hexaploid wheat may have more than one tetraploid ancestor.
Gu
Yong Qiang
YQ
United States Department of Agriculture-Agricultural Research Service, Western Regional Research Center, Albany, CA 94710, USA. ygu@pw.usda.gov
Salse
Jérôme
J
Coleman-Derr
Devin
D
Dupin
Adeline
A
Crossman
Curt
C
Lazo
Gerard R
GR
Huo
Naxin
N
Belcram
Harry
H
Ravel
Catherine
C
Charmet
Gilles
G
Charles
Mathieu
M
Anderson
Olin D
OD
Chalhoub
Boulos
B
D001483:Base Sequence / Q000235:genetics*; D021901:DNA, Intergenic; D018744:DNA, Plant / Q000032:analysis; D019143:Evolution, Molecular; D018745:Genome, Plant; D005983:Glutens / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011123:Polyploidy; D018626:Retroelements; D017422:Sequence Analysis, DNA; D026801:Synteny; D014908:Triticum / Q000235:genetics*
D021901:DNA, Intergenic; D018744:DNA, Plant; D018626:Retroelements; D005983:Glutens; C037302:glutenin