Abstract
Durum wheat (Triticum turgidum L., 2n = 4x = 28; AABB genomes) is an important cereal widely used for human consumption. It is the choice wheat for preparing pasta products. Current durum cultivars have little resistance to Fusarium head blight (FHB), or scab, a ravaging fungal disease caused by the fungal pathogen Fusarium graminearum Schwabe. We showed earlier that diploid wheatgrass (Lophopyrum elongatum (Host) Á. Löve (2n = 2x = 14; EE genome) is an excellent source of FHB resistance, which could be transferred to commercial durum cultivars by hybridization coupled with manipulation of chromosome pairing. We obtained homoeologous pairing (i.e., pairing between wheat and alien chromosomes) in intergeneric hybrids because of the wheatgrass-induced suppression of the pairing-regulating gene Ph1 of wheat, leading to alien chromatin integration into the durum genome. Adopting this chromosome engineering technology, we have transferred diploid wheatgrass chromatin into the durum genome. We have produced fertile hybrid derivatives with varying degrees of FHB resistance. Some derivatives showed only 7.6% infection compared with 72.0% in the parental durum cultivar. Fluorescent genomic in situ hybridization (fl-GISH) analysis was used to confirm the integration of alien chromatin into the durum complement.
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We are grateful to Dr. Robert Stack of the Plant Pathology Department, North Dakota State University, Fargo, for supplying the Fusarium isolates used for screening the hybrid derivatives. We also thank Dr. Steven Xu of our unit for his help in the preparation of the manuscript.