Introgression of tetraploid Thinopyrum elongatum 6EL segments enhances the stripe rust resistance of adult wheat plants

Abstract

Preventing the widespread occurrence of stripe rust in wheat largely depends on the identification of new stripe rust resistance genes and the breeding of cultivars with durable resistance. We obtained a wheat–tetraploid Thinopyrum elongatum 6E (6D) substitution line and determined that chromosome 6E contains genetic material conferring superior resistance to stripe rust at the adult stage. In this study, three novel wheat–tetraploid Th. elongatum translocation lineswere generated from the offspring of a cross between common wheat and the 6E (6D) substitution line. Genomic in situ hybridization (GISH), fluorescence in situ hybridization chromosome painting (FISH painting), repetitive sequential FISH, and 55K SNP analyses indicated that K227-48, K242-82, and K246-6 contained 42 chromosomes and were 6ES·6DL, 2DL·6EL, and 6DS·6ELtranslocation lines, respectively. The assessment of stripe rust resistance revealed that K227-48 was susceptible to a mixture of Pst races, whereas the 6EL lines K242-82 and K246-6 exhibited adult plant resistance to stripe rust. Thus, this resistance was due to the 6EL chromosome. The overall good agronomic performance of K246-6 implies this line may be a useful germplasm resource for wheat breeding programs. Furthermore, 34 PCR-based markers for chromosome 6EL were developed using the whole-genome sequence of diploid Th. elongatum. This novel translocation line may be applicable for breeding wheat lines resistant to stripe rust. Additionally, themarkers developed in this study will enablethe accurate tracing of tetraploid Th. elongatum chromosome 6E and the mapping of additional favorable genes on 6EL.