Submitted to: Chromosome Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 9, 2005
Publication Date: September 20, 2005
Citation: Xu, S.S., Faris, J.D., Cai, X., Klindworth, D.L. 2005. Molecular cytogenetic characterization and seed storage protein analysis of 1a/1d translocation in durum wheat. Chromosome Research. 13:559-568. Interpretive Summary: Durum wheat and common wheat are the two major cultivated wheats used for human consumption. Common wheat, known as bread wheat, is generally used to make bread, whereas durum wheat is generally used to produce extruded pasta products. A number of studies have demonstrated that proteins identified as 1Dx5 and 1Dy10 which are encoded by a gene located on chromosome 1D are associated with good bread-making quality in bread wheat. Because durum wheat lacks this chromosome, it generally has poor bread-making quality. To develop durum germplasm and varieties with improved bread-making quality, Dr. L. R. Joppa (ARS retired) transferred the chromosome 1D segment that carries the gene for these proteins from bread wheat cultivar 'Len' into durum wheat 'Renville'. The agronomic and quality traits of the lines carrying the transferred segment have been previously evaluated. However, the location of the breakpoint and the size of the transferred segment are unknown, and the protein constitutions of lines carrying the transferred segment are also unknown. In this study, we characterized five lines carrying the transferred segment, and their parental cultivars using molecular and cytogenetic approaches. We found that the two lines identified as L252 and S99B19 had proteins identical to those found in Langdon durum, the other three lines identified as L092, S99B33, and S99B34 had proteins identical to those found in Renville durum. We found that as a result of the transfer, that approximately 30% of the long arm of chromosome 1A had been replaced by the segment of chromosome 1DL that carries the gene for the proteins 1Dx5 and 1Dy10. Because 1Dx5 and 1Dy10 are associated with good bread-making quality in bread wheat, the lines with the transferred segment have potential for developing durum cultivars with good baking quality.
Technical Abstract: Two durum wheat [Triticum turgidum L. ssp. durum (Desf.) Husn.] lines carrying the high-molecular-weight (HMW) glutenin subunits (GS) 1Dx5+1Dy10 encoded by Glu-D1d, L252 and S99B34, were characterized using fluorescent genomic in situ hybridization (FGISH) and microsatellite markers. These two durum lines were derived from the crosses in which the hard red spring wheat cultivar 'Len' (T. aestivum L.) and two durum wheat cultivar 'Langdon' (LDN) and 'Renville' were involved. FGISH patterns of the mitotic chromosomes indicated that these two durum lines have one pair of 1AS·1AL-1DL translocated chromosomes in which the terminal fragment of 1AL was replaced by a homoeologous fragment of 1DL. The 1DL fragment spans approximately one-third of the long arm of the translocated chromosome. Microsatellite marker analysis confirmed the 1AS·1AL-1DL translocation in the durum lines and determined the translocation breakpoint to be distal to Xgwm357 on 1AL. Seed storage proteins, including glutenin subunits and gliadins, were analyzed in these two 1AS·1AL-1DL translocation lines and three sib lines (L092, S99B19, and S99B33) using sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE) and acid (A)-PAGE. The SDS-PAGE and A-PAGE profiles demonstrated that L252 and S99B19 had the low-molecular-weight (LMW) -1 GS encoded by Glu-A3k and Glu-B3s and gliadin proteins encoded by Gli-B1 from LDN and other three lines, L092, S99B33, and S99B34, had LMW-2 glutenin subunits and gliadins encoded by Gli-B1 from Renville. All five lines carried gliadin proteins encoded by Gli-A2 on the short arm of chromosome 6A from Renville. Since the HMW-GS 1Dx5+1Dy10 are associated with good bread-making quality in bread wheat and LMW-2 GS are associated with good pasta qualities in durum wheat, the translocation lines with 1Dx5+1Dy10 and LMW-2 have potentials for developing durum cultivars with dual-purpose end-use.