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Research Project: Genetic Mechanisms and Improvement of Insect Resistance in Wheat, Barley, and Sorghum

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Title: Identification and characterization of the novel leaf rust resistance gene Lr81 in wheat

Author
item Xu, Xiangyang
item Kolmer, James - Jim
item Li, Genqiao
item Tan, Chengcheng
item CARVER, BRETT - Oklahoma State University
item BIAN, RUOLIN - Arkansas State University
item Bernardo, Amy
item Bai, Guihua

Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/28/2022
Publication Date: 6/18/2022
Citation: Xu, X., Kolmer, J., Li, G., Tan, C., Carver, B.F., Bian, R., Bernardo, A., Bai, G. 2022. Identification and characterization of the novel leaf rust resistance gene Lr81 in wheat. Journal of Theoretical and Applied Genetics. Article 04145-5. https://doi.org/10.1007/s00122-022-04145-5.
DOI: https://doi.org/10.1007/s00122-022-04145-5

Interpretive Summary: Leaf rust, caused by Puccinia triticina, is the most common and widespread rust disease in wheat. Races of Puccinia triticina evolve rapidly in the southern Great Plains of the USA. Leaf rust resistance genes often lose effectiveness shortly after deployment in wheat production. PI 470121, a wheat breeding line developed by the University of Zagreb in Croatia, showed high resistance to Puccinia triticina races collected from Oklahoma, suggesting that PI 470121 could be a leaf rust resistance source for the southern Great Plains of the USA. Genetic analysis indicated that PI 470121 carries a dominant seedling resistance gene, designated as LR81, and linkage mapping delimited LR81 to a genomic region of 96,148 bp on the short arm of chromosome 2A, spanning 67,030,206 – 67,132,354 bp in the Chinese Spring reference assembly (IWGSC RefSeq v1.0). Allelism tests indicated that LR81 represents a novel leaf rust resistance locus. Lr81 is a valuable leaf rust resistance source that can be rapidly introgressed into locally adapted cultivars using KASP markers developed in this study.

Technical Abstract: Key Message-The novel, leaf rust seedling resistance gene, Lr81, was identified in a Croatian breeding line and mapped to a genomic region of less than 100 Kb on chromosome 2AS. Leaf rust, caused by Puccinia triticina, is the most common and widespread rust disease in wheat. Races of Puccinia triticina evolve rapidly in the southern Great Plains of the USA and leaf rust resistance genes often lose effectiveness shortly after deployment in wheat production. PI 470121, a wheat breeding line developed by the University of Zagreb in Croatia, showed high resistance to Puccinia triticina races collected from Oklahoma, suggesting that PI 470121 could be a leaf rust resistance source for the southern Great Plains of the USA. Genetic analysis based on an F2 population and F2:3 families derived from the cross PI 470121 × Stardust indicated that PI 470121 carries a dominant seedling resistance gene, designated as LR81. Linkage mapping delimited LR81 to a genomic region of 96,148 bp flanked by newly developed KASP markers Xstars-KASP320 and Xstars-KASP323 on the short arm of chromosome 2A, spanning 67,030,206 – 67,132,354 bp in the Chinese Spring reference assembly (IWGSC RefSeq v1.0). Deletion bin mapping assigned LR81 to the terminal bin 2AS-0.78-1.00. Allelism tests indicated that LR81 is a distinctive leaf rust resistance locus with the physical order LR65-LR17-LR81. Marker-assisted selection based on a set of markers closely linked to leaf rust resistance genes in PI 470121 and Stardust enable identification of a recombinant inbred line RIL92 carrying Lr81 only. Lr81 is a valuable leaf rust resistance source that can be rapidly introgressed into locally adapted cultivars using KASP markers Xstars-KASP320 and Xstars-KASP323.