Cytological and Molecular Characterization of Homoeologous Group-1 Chromosomes in Hybrid Derivatives of a Durum Disomic Alien Addition Line

Authors: Jauhar, Prem; Peterson, Terrance

Submitted to: The Plant Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/11/2011
Publication Date: 7/2/2011
Citation: Jauhar, P.P., Peterson, T.S. 2011. Cytological and Molecular Characterization of Homoeologous Group-1 Chromosomes in Hybrid Derivatives of a Durum Disomic Alien Addition Line. The Plant Genome. 4(2):102-109.

Interpretive Summary: Fusarium head blight (FHB), also called scab, is a serious disease of durum wheat, or macaroni wheat that is widely used for human consumption in the Unites States, Canada, and Europe. To incorporate FHB resistance from a wild wheatgrass that is diploid (with only two sets of chromosomes – rod-like structures that carry the genes for various traits), we produced earlier a durum line, DGE-1, incorporating chromosome 1E of wild grass. DGE-1, released in 2008, is the first alien addition line of its kind with a novel source of resistance in the added chromosome 1E from a wild grass. However, for stable incorporation of FHB resistance into cultivated durum cultivars it is necessary to transfer this resistance from the added alien chromosome 1E into a related durum chromosome 1A or 1B. Moreover, such a transfer is more likely to occur when these target chromosomes are in a single dose in hybrids of DGE-1, which we produced with chromosomes 1A, 1B, 1D, and 1E in a single dose. As an important first step, we standardized a method to readily identify these group-1 chromosomes and detect a desired segmental interchange among them. A sophisticated technique, called multicolor fluorescent genomic in situ hybridization (fl-GISH) that we standardized earlier, is useful for such identification, although this cytological technique is tedious and expensive. To identify all the group-1 chromosomes more expeditiously as well as economically in a large number of plants, we identified and used chromosome-specific molecular markers and were able to identify each of the group-1 chromosomes. These studies should hasten our scab resistance breeding program.

Technical Abstract: Fusarium head blight (FHB) is a devastating disease of durum wheat (Triticum turgidum L., 2n = 4x = 28; AABB). To incorporate FHB resistance from diploid wheatgrass (Lophopyrum elongatum (Host) Á. Löve, 2n = 2x = 14; EE) we produced earlier a stable alien disomic addition line, DGE-1, incorporating chromosome 1E of the alien donor into durum cultivar Langdon. DGE-1, released in 2008, is the first durum alien addition line with a novel source of resistance from alien chromosome 1E. However, for stable FHB resistance it is necessary to transfer resistance from 1E into homoeologous group-1 durum chromosomes 1A or 1B. Such transfer is more likely to occur when these target chromosomes are in a single dose. We crossed DGE-1 with Langdon substitution lines, 1D(1A) and 1D(1B), and produced hybrid derivatives with chromosomes 1A, 1B, 1D, and 1E in a single dose. As an important first step, we standardized a method to readily identify these group-1 chromosomes. Multicolor fluorescent genomic in situ hybridization (fl-GISH) that we standardized earlier is useful for such identification, but is tedious and expensive. To identify these chromosomes more expeditiously and economically in a large number of plants, we used chromosome-specific molecular markers and were able to identify each of the group-1 chromosomes. We used marker Xwmc333 for identifying chromosome 1A, Xwgm18 for 1B, Xwmc147 for 1D, and Xedm17 for 1E. Xedm17 that profiles chromosome 1E also generated 2 characteristic bands for chromosome 1D, and may therefore be used to identify both these chromosomes simultaneously.