Molecular and phenotypic characterization of seedling and adult plant leaf rust resistance in a world wheat collection.
Genetic resistance is the most effective approach to managing wheat leaf rust. The aim of this study was to characterize seedling and adult plant leaf rust resistance of a world wheat collection. Using controlled inoculation with ten races ofPuccinia triticina, 14 seedling resistance genes were determined or postulated to be present in the collection.Lr1,Lr3,Lr10andLr20were the most prevalent genes around the world whileLr9,Lr14b,Lr3kaand/orLr30andLr26were rare. To confirm some gene postulations, the collection was screened with gene-specific molecular markers forLr1,Lr10,Lr21andLr34. Although possessing theLr1and/orLr10gene-specific marker, 51 accessions showed unexpected high infection types toP. triticinarace BBBD. The collection was tested in the field, where rust resistance ranged from nearly immune or highly resistant with severity of 1 % and resistant host response to highly susceptible with severity of 84 % and susceptible host response. The majority of the accessions possessing the adult plant resistance (APR) geneLr34had a maximum rust severity of 0-35 %, similar to or better than accession RL6058, a Thatcher-Lr34near-isogenic line. Many accessions displayed an immune response or a high level of resistance under field conditions, likely as a result of synergy between APR genes or between APR and seedling resistance genes. However, accessions with three or more seedling resistance genes had an overall lower field severity than those with two or fewer. Immune or highly resistant accessions are potential sources for improvement of leaf rust resistance. In addition, some lines were postulated to have known but unidentified genes/alleles or novel genes, also constituting potentially important sources of novel resistance.
Cereal Research Centre, Agriculture and Agri-Food Canada, 195 Dafoe Road, Winnipeg, MB R3T 2M9 Canada ; Department of Plant Science, University of Manitoba, 66 Dafoe Road, Winnipeg, MB R3T 2N2 Canada.
Abdulsalam
A
Dakouri
Brent D
BD
McCallum
Natasa
N
Radovanovic
Sylvie
S
Cloutier
APR genes; Gene postulation; Lr genes; Puccinia triticina; Triticum aestivum