Thinopyrum elongatum (2 n = 4 x = 28) harbors multiple valuable resistance genes and serves as a valuable genetic resource for wheat improvement. Yr1EL was primarily identified on chromosome arm 1EL of tetraploid Th. elongatum , conferring adult-plant resistance to stripe rust. To further map and utilize Yr1EL , we introduced chromosomal rearrangements by crossing the wheat–tetraploid Th. elongatum 1E(1D) substitution line and the T1BS·1EL translocation line with the common wheat Chinese Spring ph1b mutant. In total, eight wheat– Th. elongatum chromosome 1E structural variants were identified by in situ hybridization, the GenoBaits®WheatplusEE panel, and molecular markers. These variants include one large segment translocation, one terminal fragment deletion, one chromosome 1E insertion translocation, and five chromosome 1EL terminal small fragment translocations. Based on phenotyping and genotyping of these variant lines, Yr1EL was mapped to an approximately 20.91 Mb physical interval (532.45 to 553.35 Mb) on the distal long arm of chromosome 1E corresponding to the diploid Th. elongatum reference genome . Genetic analysis confirmed that stripe rust resistance was conferred by the Yr1EL locus with incomplete dominance. Five codominant molecular markers co-segregated with the Yr1EL locus and will facilitate marker-assisted selection . Furthermore, collinearity analysis showed that this interval is structurally conserved among Triticeae species, and 29 candidate genes potentially related to disease resistance were annotated. Those candidates included receptor-like proteins, kinases, nucleotide-binding and leucine-rich repeat receptors, and other disease resistance proteins. The adult-plant resistance gene Yr1EL expands the wheat disease-resistance gene pool and provides valuable germplasm for breeding durable stripe rust-resistant cultivars.
Wu et al. (Fri,) studied this question.