Mapping and characterization of the new adult plant leaf rust resistance gene Lr77 derived from Santa Fe winter wheat

Authors: Kolmer, James; ZHI, SU - Kansas State University; BERNARDO, AMY - Kansas State University; HAYDEN, MATTHEW - La Trobe University; Chao, Shiaoman

Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/8/2018
Publication Date: 5/8/2018
Citation: Kolmer, J.A., Zhi, S., Bernardo, A.N., Hayden, M.J., Chao, S. 2018. Mapping and characterization of the new adult plant leaf rust resistance gene Lr77 derived from Santa Fe winter wheat. Journal of Theoretical and Applied Genetics. 131(7):1553-1560. https://doi.org/10.1007/s00122-018-3097-3.
DOI: https://doi.org/10.1007/s00122-018-3097-3

Interpretive Summary: Wheat is attacked by the leaf rust fungus, Puccinia triticina. Genes in wheat can provide resistance to this important pathogen and disease of wheat. The wheat cultivar Santa Fe which was developed in the United States, has had long lasting resistance to leaf rust. The objective of this research was to determine on what chromosome the long lasting leaf rust resistance gene in Santa Fe is found. Santa Fe had a major gene for leaf rust resistance on chromosome 3BL. The resistance gene on 3BL was a new gene and was designated as Lr77. Santa Fe can be used as a parent by wheat breeders and plant pathologists to improve the leaf rust resistance in wheat improvement programs.

Technical Abstract: Santa Fe is a hard red winter cultivar that has had long lasting resistance to the leaf rust fungus, Puccinia triticina. The objective of this study was to determine the chromosome location of the adult plant leaf rust resistance in Santa Fe wheat. A partial backcross line of 'Thatcher' (Tc) wheat with adult plant leaf rust resistance derived from Santa Fe was crossed with Thatcher to develop a Thatcher//Tc*2/Santa Fe F6 recombinant inbred line (RIL) population. The RIL population and parental lines were evaluated for segregation of leaf rust resistance in three field plot tests and in an adult plant greenhouse test. A genetic map of the RIL population was constructed using 90,000 single-nucleotide polymorphism (SNP) markers with the Illumina Infinium iSelect 90K wheat bead array. A significant quantitative trait locus (QTL) for reduction of leaf rust severity in all four tests was found on chromosome 3BL that segregated as a single adult plant resistance gene. The RILs with the allele from the resistant parent for SNP marker IWB10344 had lower leaf rust severity and a moderately resistant to moderately susceptible response compared to the susceptible RILs and Thatcher. The gene derived from Santa Fe on chromosome 3BL was designated as Lr77. Kompetitive allele specific polymerase chain reaction (KASP) assay markers linked to Lr77 on 3BL should be useful for selection of wheat germplasm with this gene.