Location: Cereal Disease LabTitle: A QTL on chromosome 5BL in wheat enhances leaf rust resistance of Lr46
Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/28/2015
Publication Date: 2/8/2015
Citation: Kolmer, J.A. 2015. A QTL on chromosome 5BL in wheat enhances leaf rust resistance of Lr46. Molecular Breeding. 35:74-81.
Interpretive Summary: Wheat is attacked by Puccinia triticina, which is the scientific name of the fungus that causes the disease wheat leaf rust. This disease occurs world wide. The purpose of this study was to genetically characterize the leaf rust resistance found in an old wheat cultivar from Uruguay, Americano 25e. The leaf rust resistance in Americano 25e was determined to be present on the long arm of chromosome 1B and also on the long arm of chromosome 5B. Both resistance genes are most effective when the plants have headed and are flowering. The resistance on chromosome 1B is likely the gene Lr46 which is present in many wheats that have had good long lasting resistance to leaf rust. The resistance on chromosome 5B enhanced the resistance of Lr46 in an additive manner. Plants with both genes are more resistant than plants with only a single gene. Wheat plants with the combination of Lr46 and the resistance on chromosome 5B can be used in wheat breeding projects for improvement of leaf rust resistance.
Technical Abstract: Combinations of effective leaf rust resistance genes that condition resistance to many leaf rust phenotypes are key to the development of wheat cultivars with long lasting resistance to leaf rust caused by Puccinia triticina. A population of 100 F6 recombinant inbred lines (RILs) derived from the cross 'Thatcher*3/Americano 25e' was evaluated for segregation of adult plant leaf rust resistance in field plot tests and in a greenhouse test. A genetic map was constructed with 243 diversity array markers. Significant effects for reduction of leaf rust severity were found on chromosomes 1BL and 5BL. The sequence tagged site marker csLV46, closely linked to Lr46 mapped to the logarithm of odds peak on chromosome 1BL, indicating that the RILs were likely segregating for this adult plant resistance gene. Lines with csLV46 had an average leaf rust severity of 35% in the four tests. RILs with the resistance on chromosome 5BL designated as QLr.cdl-5BL, had an average leaf rust severity of 47%. RILS with both csLV46 and QLr.cdl – 5BL had an average leaf rust severity of 22%, close to the Thatcher*2/Americano 25e parental line. The QLr.cdl-5BL region enhanced the leaf resistance conditioned by Lr46 in an additive manner.