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United States Department of Agriculture

Agricultural Research Service

Research Project: GENETICS, POPULATION BIOLOGY, AND HOST-PARASITE INTERACTIONS OF CEREAL RUST FUNGI AND THEIR DISEASES

Location: Cereal Disease Laboratory

Title: Molecular mapping and improvement of leaf rust resistance in wheat breeding lines

Authors
item Toi, John -
item Kolmer, James
item Anderson, James -

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 7, 2014
Publication Date: August 1, 2014
Citation: Toi, J., Kolmer, J.A., Anderson, J. 2014. Molecular mapping and improvement of leaf rust resistance in wheat breeding lines. Phytopathology. 104:265-870..

Interpretive Summary: Wheat is attacked by a fungus called Puccinia triticina that causes the disease wheat leaf rust. Wheat leaf rust is very common in both North America and worldwide. Wheat has genes that give resistance to the fungus. The purpose of this study was to identify which leaf rust resistance (Lr) genes are present in two wheat cultivars from Minnesota and identify DNA markers associated with the resistance genes. Leaf rust resistance genes Lr2a, Lr16, and Lr34 were identified in the two cultivars. Molecular markers associated with the three genes were also identified. This information will be useful to plant breeders and plant pathologists for improving leaf rust resistance in wheat.

Technical Abstract: Wheat leaf rust, caused by Puccinia triticina, is the most common and widespread disease of wheat (Triticum aestivum L.) worldwide. Wheat leaf rust, caused by Puccinia triticina, is widely distributed worldwide. Deployment of host-plant resistance is one of the strategies to reduce losses due to leaf rust disease. The objective of this study was to map genes for adult-plant resistance to leaf rust in a recombinant inbred line (RIL) population originating from MN98550-5/MN99394-1. The mapping population of 139 RILs and five checks were evaluated in 2005, 2009, and 2010 in five environments. Natural infection occurred in 2005 and the trials were inoculated in 2009 and 2010. Four QTL on chromosomes 2BS, 2DS, 7AL, and 7DS were detected. The QTL on 2BS explained up to 33.5% of the phenotypic variation in leaf rust response, whereas the 2DS, 7AL, and 7DS QTL explained up to 16, 7, and 35%, respectively. Seedling infection type tests conducted with races BBBD and SBDG confirmed that the QTL on 2BS and 2DS were Lr16 and Lr2a, respectively, and these genes are expressed at the seedling and adult plant stages. The QTL on 7DS was Lr34. The QTL on 7AL was a new QTL for leaf rust. The Lr2a gene mapped at the same location as Sr6. The joint-effects of all four QTL explained 74% of the total phenotypic variation in leaf rust severity. Analysis of different combinations of QTL showed that the RILs containing all four QTL had the lowest average leaf rust severity in all five environments. Deployment of these QTL in combination or with other effective genes will lead to successful control of leaf rust.

Last Modified: 9/20/2014
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