title: The Vh8 locus of a new gene-for-gene interaction between Venturia inaequalis and the wild apple Malus sieversii is closely linked to the Vh2 locus in Malus pumila R12740-7A.
abstract: The wild apple (Malus sieversii) is a large-fruited species from Central Asia, which is used as a source of scab resistance in cultivar breeding. Phytopathological tests with races of Venturia inaequalis were performed to differentiate scab-resistance genes in Malus as well as an avirulence gene in the pathogen. A novel gene-for-gene interaction between V. inaequalis and Malus was identified. The locus of the scab-resistance gene Vh8 is linked with, or possibly allelic to, that of the Vh2 gene in Malus pumila Russian apple R12740-7A, at the lower end of linkage group 2 of Malus. Race 8 isolate NZ188B.2 is compatible with Vh8, suggesting the loss or modification of the complementary AvrVh8 gene, while isolate 1639 overcomes both Vh2 and Vh8, but is incompatible with at least one other gene not detected by any of the other race isolates tested. Our research is the first to differentiate scab-resistance genes in a putative gene cluster in apple with the aid of races of V. inaequalis.
authors.affiliation: The Horticulture and Food Research Institute of New Zealand Ltd, Hawkes Bay Research Centre, Havelock North, Private Bag 1401, New Zealand. vbus@hortresearch.co.nz
authors.forename: Vincent G M
authors.initials: VG
authors.lastname: Bus
authors.forename: François N D
authors.initials: FN
authors.lastname: Laurens
authors.forename: W Eric
authors.initials: WE
authors.lastname: van de Weg
authors.forename: Rachel L
authors.initials: RL
authors.lastname: Rusholme
authors.forename: Erik H A
authors.initials: EH
authors.lastname: Rikkerink
authors.forename: Susan E
authors.initials: SE
authors.lastname: Gardiner
authors.forename: Heather C M
authors.initials: HC
authors.lastname: Bassett
authors.forename: Linda P
authors.initials: LP
authors.lastname: Kodde
authors.forename: Kim M
authors.initials: KM
authors.lastname: Plummer
mesh_terms: D001203:Ascomycota / Q000235:genetics* / Q000472:pathogenicity; D002874:Chromosome Mapping; D032461:Chromosomes, Plant; D005800:Genes, Fungal; D017343:Genes, Plant; D005819:Genetic Markers; D007113:Immunity, Innate / Q000235:genetics; D027845:Malus / Q000235:genetics* / Q000382:microbiology; D010935:Plant Diseases / Q000235:genetics*; D018515:Plant Leaves / Q000382:microbiology; D014774:Virulence / Q000235:genetics
chemical_list: D005819:Genetic Markers