Submitted to: Plant and Animal Genome VX Conference Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 10/5/2003
Publication Date: 1/9/2004
Citation: Simons, K., Fellers, J.P., Trick, H., Gill, B.S., Faris, J.D. 2004. Molecular cloning of the Q locus in wheat. Plant and Animal Genome Abstracts. p. 110.
Technical Abstract: The Q locus played a major role in the domestication of polyploid wheat because it confers the square-headed phenotype and the free-threshing character, and it pleiotropically influences many other agronomically important traits. A physical contig spanning the Q locus on chromosome 5A was constructed using a Triticum monococcum BAC library. The 100 kb segment cosegregating with Q contained an APETELA2 (AP2)-like gene. This gene is a likely candidate for Q because AP2 plays a major role in controlling floral homeotic gene expression in Arabidopsis. The AP2-like gene was sequenced from the free-threshing T. aestivum cultivar Chinese Spring, the free-threshing T. turgidum cultivar Langdon, and several nonfree-threshing wild relatives. Sequence comparisons revealed slight differences between free-threshing and nonfree-threshing species. EMS-treated T. aestivum lines were screened for mutations in the Q locus. Of six mutant lines, three were the result of large deletions encompassing the Q locus. The AP2-like gene in the remaining three lines had base substitutions that resulted in coding of a different amino acid or the alteration of a predicted exon/intron splice site. Transgenic individuals were created using a 5 kb subclone of a T. turgidum BAC containing the Q locus. These transgenic individuals mimicked the increased or decreased dosage effect of Q, suggesting the occurrence of silencing and over-expression, respectively.