Submitted to: Journal of Crop Improvement
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/27/2009
Publication Date: 10/15/2009
Citation: Jauhar, P.P., Peterson, T.S. 2009. Chromosome Engineering of Durum Wheat with Alien Chromatin of Diploid Wheatgrass. Journal of Crop Improvement. 23(4)319-331.
Interpretive Summary: Durum or macaroni wheat is an important cereal crop widely used for human consumption. It is a choice wheat for preparing pasta products Fusarium head blight (FHB), popularly known as scab, is a devastating disease of both bread wheat and durum wheat, causing huge losses to farmers. There is little or no scab resistance in current durum cultivars. Therefore, potential wild donors of FHB resistance need to be explored. Earlier, we found that a wild grass, called diploid wheatgrass (technically named Lophopyrum elongatum), is highly resistant to scab. By crossing a durum cultivar, Langdon, with this grass we produced several hybrids. Some hybrids showed pairing between the durum and grass chromosomes (rod-like structures that carry the genes of interest). Through further crossing, we transferred some segments of grass chromosomes into durum wheat. Adopting this “chromosome engineering” technology, we have produced some fertile hybrid derivatives with varying degrees of FHB resistance. Some derivatives showed only 7.9% infection compared to 68.3% in the parental durum cultivar. Using a sophisticated cytological technique, called “fuorescent genomic in situ hybridization”, we have confirmed the integration of alien chromatin into the durum complement. The technique of alien chromatin transfer into the durum wheat genome is outlined and its value in breeding for scab resistance is briefly discussed.
Technical Abstract: Durum or macaroni wheat (Triticum turgidum L., 2n = 4x = 28; AABB genomes) is an important cereal used for human consumption worldwide. Its high protein content and gluten strength make durum the choice wheat for preparing pasta products. Current durum cultivars have little resistance to Fusarium head blight (FHB), or scab, a ravaging disease caused by the fungal pathogen Fusarium graminearum Schwabe. We showed earlier that a diploid wheatgrass Lophopyrum elongatum (Host) Á. Löve (2n = 2x = 14; EE) is an excellent source of FHB resistance, which could be transferred to commercial durum cultivars by hybridization coupled with manipulation of chromosome pairing. Ph1 gene, located in the long arm of chromosome 5B, restricts pairing to homologous partners. Suppression or partial inactivation of Ph1 by the L. elongatum genotype allows enough homoeologous pairing to cause alien chromatin integration into the durum genome. Adopting this chromosome engineering technology, we have transferred chromatin from diploid wheatgrass into the durum genome and produced some fertile hybrid derivatives with varying degrees of FHB resistance. Some derivatives showed only 7.9% infection compared to 68.3% in the parental durum cultivar. Using fluorescent genomic in situ hybridization (fl-GISH), we have confirmed the integration of alien chromatin into the durum complement. The technique of alien chromatin transfer into the durum wheat genome is outlined and its value in breeding for scab resistance is briefly discussed.