title: Partial resistance to powdery mildew in German spring wheat 'Naxos' is based on multiple genes with stable effects in diverse environments.
abstract: Powdery mildew is one of the most important wheat diseases in temperate regions of the world. Resistance breeding is considered to be an economical and environmentally benign way to control this disease. The German spring wheat cv. 'Naxos' exhibits high levels of partial and race non-specific resistance to powdery mildew in the field and is a valuable source in resistance breeding. The main objective of the present study was to map the genetic factors behind the resistance in Naxos, based on a population of recombinant inbred lines (RIL) from a cross with the susceptible CIMMYT breeding line SHA3/CBRD. Powdery mildew severity was evaluated in six field trials in Norway and four field trials in China. The major quantitative trait locus (QTL) with resistance from Naxos was detected close to the Pm3 locus on 1AS in all environments, and explained up to 35% of the phenotypic variation. Naxos was shown to carry another major QTL on 2DL and minor ones on 2BL and 7DS. QTL with resistance from SHA3/CBRD were detected on 1RS, 2DLc, 6BL and 7AL. The QTL on the 1B/1R translocation showed highly variable effects across environments corresponding to known virulence differences against Pm8. SHA3/CBRD was shown to possess the Pm3 haplotype on 1AS, but none of the known Pm3a-g alleles. The RIL population did not provide any evidence to suggest that the Pm3 allele of SHA3/CBRD acted as a suppressor of Pm8.
authors.affiliation: Department of Plant and Environmental Sciences, Norwegian University of Life Sciences, PO Box 5003, 1432 Aas, Norway.
authors.forename: Qiongxian
authors.initials: Q
authors.lastname: Lu
authors.forename: Åsmund
authors.initials: Å
authors.lastname: Bjørnstad
authors.forename: Yan
authors.initials: Y
authors.lastname: Ren
authors.forename: Muhammad Azeem
authors.initials: MA
authors.lastname: Asad
authors.forename: Xianchun
authors.initials: X
authors.lastname: Xia
authors.forename: Xinmin
authors.initials: X
authors.lastname: Chen
authors.forename: Fang
authors.initials: F
authors.lastname: Ji
authors.forename: Jianrong
authors.initials: J
authors.lastname: Shi
authors.forename: Morten
authors.initials: M
authors.lastname: Lillemo
mesh_terms: D000483:Alleles; D000704:Analysis of Variance; D001203:Ascomycota / Q000502:physiology*; D002681:China; D002874:Chromosome Mapping; D032461:Chromosomes, Plant / Q000235:genetics; D003433:Crosses, Genetic; D060467:Disease Resistance / Q000276:immunology*; D004777:Environment; D004843:Epistasis, Genetic; D017343:Genes, Plant / Q000235:genetics*; D005858:Germany; D006239:Haplotypes / Q000235:genetics; D007178:Inbreeding; D009664:Norway; D010641:Phenotype; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D040641:Quantitative Trait Loci; D012044:Regression Analysis; D012621:Seasons; D014908:Triticum / Q000235:genetics* / Q000276:immunology / Q000382:microbiology*