Mapping of Aegilops umbellulata‐derived leaf rust and stripe rust resistance loci in wheat

Abstract

Aegilops umbellulata, a non-progenitor diploid species, is an excellent source of resistance to various wheat diseases. Leaf rust and stripe rust resistance genes from A. umbellulata were transferred to the susceptible wheat cultivar WL711 through induced homoeologous pairing. A doubly resistant introgression line IL 393-4 was crossed with wheat cultivar PBW343 to develop a mapping population. Tests on BC 2 F 7 RILs indicated monogenic inheritance of seedling leaf rust and stripe rust resistance in IL 393-4 and the respective co-segregating genes were tentatively named LrUmb and YrUmb. Bulked segregant analysis placed LrUmb and YrUmb in chromosome 5DS, 7.6 cM distal to gwm190. Aegilops geniculata-derived and completely linked leaf rust and stripe rust resistance genes Lr57 and Yr40 were previously located in chromosome 5DS. STS marker Lr57/Yr40MAS-CAPS16 (Lr57/Yr40-CAPS16), linked with Lr57/Yr40 (T756) also co-segregated with LrUmb/YrUmb. Seedling infection types differentiated LrUmb from Lr57. Absence of leaf rust-susceptible segregants among F 3 families of the intercross (IL 393-4/T756) indicated repulsion linkage between LrUmb and Lr57. YrUmb expressed a consistently low seedling response under greenhouse conditions, whereas Yr40 expressed a higher seedling response. Based on the origin of LrUmb/YrUmb from the U genome and Lr57/Yr40 from the M genome, as well as phenotypic differences, LrUmb and YrUmb were formally named Lr76 and Yr70, respectively. These genes have been transferred to Indian wheat cultivars PBW343 and PBW550, and advanced breeding lines are being tested in state and national trials.

The Transcriptional Landscape of Polyploid Wheats and Their Diploid Ancestors during Embryogenesis and Grain Development

“…Furthermore, as a result of polyploidization, most genes in tetraploid and hexaploid wheat species are present in multiple copies, referred to as homeologs from corresponding genes among A, B, and D subgenomes (Devos, 2010;Glover et al, 2016;Krasileva et al, 2017). Examining gene expression in the expanding ploidy levels of various wheat species and identifying and characterizing their corresponding homologs (referring to common ancestry) and homeologs (referring to corresponding genes from three subgenomes) in the diploid ancestral grass species has the potential to reveal their divergence and respective functionalities among wheat species subjected to agricultural selective pressures (Hills et al, 2007;Bansal et al, 2017;Ramírez-González et al, 2018). Despite the importance of hybridization and polyploidization in the history of wheat, our understanding of the gene expression changes and evolutionary divergence of embryogenesis from diploids to polyploids is limited.…”

Stripe rust resistance genes in a set of Ethiopian bread wheat cultivars and breeding lines

“…Yr50 from Thinopyrum intermedium (Liu et al 2013), Yr70 from Ae. umbellulata (Bansal et al 2016). Other genes came from hexaploid wheat landraces (McIntosh et al 2016).…”

Comparative Temporal Transcriptome Profiling of Wheat near Isogenic Line Carrying Lr57 under Compatible and Incompatible Interactions

“…Nevertheless, numerous genes involved in the wheat- P. triticina response have been identified. More than 76 genes for leaf rust have been cataloged so far and Lr1, Lr10, Lr21, Lr34 , and Lr67 have been isolated and characterized through map based cloning approach (McIntosh et al, 2013; Bansal et al, 2017). …”