Chromosome Engineering of Durum Wheat with Alien Chromatin of Diploid Wheatgrass

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.