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GrainGenes Reference Report: PMB-54-55

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Reference	PMB-54-55
Title	Dynamics of the evolution of orthologous and paralogous portions of a complex locus region in two genomes of allopolyploid wheat
Journal	Plant Molecular Biology
Year	2004
Volume	54
Pages	55-69
Author	Kong XY Gu YQ You FM Dubcovsky J Anderson OD
Abstract	Summary: Two overlapping bacterial artificial chromosome (BAC) clones from the B genome of the tetraploid wheat Triticum turgidum were identified, each of which contains one of the two high-molecular-weight (HMW) glutenin genes, comprising the complex Glu-B1 locus. The complete sequence (285 506 bp of DNA) of this chromosomal region was determined. The two paralogous x-type (Glu-1-1) and y-type (Glu-1-2) HMW-glutenin genes of the complex Glu-B1 locus were found to be separated by ca. 168 000 bp instead of the 51 000 bp separation previously reported for the orthologous Glu-D1 locus of Aegilops tauschii, the D-genome donor of hexaploid wheat. This difference in intergene spacing is due almost entirely to be the insertion of clusters of nested retrotransposons. Otherwise, the orientation and order of the HMW glutenins and adjacent genes were identical in the two genomes. A comparison of these orthologous regions indicates modes and patterns of sequence divergence, with implications for the overall Triticeae genome structure and evolution. A duplicate globulin gene, found 5' of each HMW-glutenin gene, assists to tentatively define the original duplication event leading to the paralogous x- and y-type HMW-glutenin genes. The intergenic regions of the two loci are composed of different patterns and classes of retrotransposons, indicating that insertion times of these retroelements were after the divergence of the two wheat genomes. In addition, a putative receptor kinase gene near the y-type HMW-glutenin gene at the Glu-B1 locus is likely active as it matches recently reported ESTs from germinating barley endosperm. The presence of four genes represented only in the Triticeae endosperm ESTs suggests an endosperm-specific chromosome domain
External Databases	Pubmed: 15159634
Keyword	[ Hide all but 1 of 59 ] aegilops allopolyploid b genome bac bacterial bacterial artificial chromosome barley barley endosperm bread wheat chromosome clone cluster comparative sequence-analysis complete sequence complexes difference disease resistance divergence dna domain duplication dynamics endosperm endosperm-specific evolution gene genome genome structure germinating barley globulin grass genomes hexaploid hexaploid wheat hmw glutenin hmw-glutenins insertion intergenic region kinase molecular-weight glutenin orientation orthologous region portion receptor receptor kinase recombination retrotransposon retrotransposons rice separation sequence structure subunit gene tauschii tetraploid tetraploid wheat transgenic wheat triticeae triticum turgidum

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