title: Consensus mapping of major resistance genes and independent QTL for quantitative resistance to sunflower downy mildew.
abstract: Major gene resistance to sunflower downy mildew (Plasmopara halstedii) races 304 and 314 was found to segregate independently from the resistance to races 334, 307 and 304 determined by the gene Pl2, already positioned on Linkage Group (LG) 8 of sunflower molecular maps. Using a consensus SSR-SNP map constructed from the INEDI RIL population and a new RIL population FU × PAZ2, the positions of Pl2 and Pl5 were confirmed and the new gene, denoted Pl21, was mapped on LG13, at 8 cM from Pl5. The two RIL populations were observed for their quantitative resistance to downy mildew in the field and both indicated the existence of a QTL on LG8 at 20-40 cM from the major resistance gene cluster. In addition, for the INEDI population, a strong QTL on LG10, reported previously, was confirmed and a third QTL was mapped on LG7. A growth chamber test methodology, significantly correlated with field results, also revealed the major QTL on LG10, explaining 65 % of variability. This QTL mapped in the same area as a gene involved in stomatal opening and root growth, which may be suggested as a possible candidate to explain the control of this character. These results indicate that it should be possible to combine major genes and other resistance mechanisms, a strategy that could help to improve durability of sunflower resistance to downy mildew.
authors.affiliation: Laboratoire des Interactions Plantes-Microorganismes (LIPM), INRA, UMR441, 31326 Castanet-Tolosan, France. patrick.vincourt@toulouse.inra.fr
authors.forename: Patrick
authors.initials: P
authors.lastname: Vincourt
authors.forename: Falah
authors.initials: F
authors.lastname: As-Sadi
authors.forename: Amandine
authors.initials: A
authors.lastname: Bordat
authors.forename: Nicolas B
authors.initials: NB
authors.lastname: Langlade
authors.forename: Jerome
authors.initials: J
authors.lastname: Gouzy
authors.forename: Nicolas
authors.initials: N
authors.lastname: Pouilly
authors.forename: Yannick
authors.initials: Y
authors.lastname: Lippi
authors.forename: Frédéric
authors.initials: F
authors.lastname: Serre
authors.forename: Laurence
authors.initials: L
authors.lastname: Godiard
authors.forename: Denis
authors.initials: D
authors.lastname: Tourvieille de Labrouhe
authors.forename: Felicity
authors.initials: F
authors.lastname: Vear
mesh_terms: D002874:Chromosome Mapping; D032461:Chromosomes, Plant / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D017343:Genes, Plant / Q000235:genetics*; D005819:Genetic Markers; D005838:Genotype; D006368:Helianthus / Q000235:genetics* / Q000276:immunology / Q000382:microbiology*; D007113:Immunity, Innate / Q000235:genetics*; D015810:Linkage Disequilibrium; D009868:Oomycetes / Q000472:pathogenicity*; D010935:Plant Diseases / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic / Q000235:genetics; D040641:Quantitative Trait Loci
chemical_list: D018744:DNA, Plant; D005819:Genetic Markers