title: The knock-down of the expression of MdMLO19 reduces susceptibility to powdery mildew (Podosphaera leucotricha) in apple (Malus domestica).
abstract: Varieties resistant to powdery mildew (PM; caused by Podosphaera leucotricha) are a major component of sustainable apple production. Resistance can be achieved by knocking-out susceptibility S-genes to be singled out among members of the MLO (Mildew Locus O) gene family. Candidates are MLO S-genes of phylogenetic clade V up-regulated upon PM inoculation, such as MdMLO11 and 19 (clade V) and MdMLO18 (clade VII). We report the knock-down through RNA interference of MdMLO11 and 19, as well as the complementation of resistance with MdMLO18 in the Arabidopsis thaliana triple mlo mutant Atmlo2/6/12. The knock-down of MdMLO19 reduced PM disease severity by 75%, whereas the knock-down of MdMLO11, alone or in combination with MdMLO19, did not result in any reduction or additional reduction of susceptibility compared with MdMLO19 alone. The test in A. thaliana excluded a role for MdMLO18 in PM susceptibility. Cell wall appositions (papillae) were present in both PM-resistant and PM-susceptible plants, but were larger in resistant lines. No obvious negative phenotype was observed in plants with mlo genes knocked down. Apparently, MdMLO19 plays the pivotal role in apple PM susceptibility and its knock-down induces a very significant level of resistance.
authors.affiliation: Research and Innovation Center, Fondazione Edmund Mach, San Michele all'Adige, Italy.|Wageningen UR Plant Breeding, Wageningen University and Research Centre, Wageningen, The Netherlands.
authors.forename: Stefano
authors.initials: S
authors.lastname: Pessina
authors.affiliation: Research and Innovation Center, Fondazione Edmund Mach, San Michele all'Adige, Italy.
authors.forename: Dario
authors.initials: D
authors.lastname: Angeli
authors.affiliation: Research and Innovation Center, Fondazione Edmund Mach, San Michele all'Adige, Italy.
authors.forename: Stefan
authors.initials: S
authors.lastname: Martens
authors.affiliation: Wageningen UR Plant Breeding, Wageningen University and Research Centre, Wageningen, The Netherlands.
authors.forename: Richard G F
authors.initials: RG
authors.lastname: Visser
authors.affiliation: Wageningen UR Plant Breeding, Wageningen University and Research Centre, Wageningen, The Netherlands.
authors.forename: Yuling
authors.initials: Y
authors.lastname: Bai
authors.affiliation: Research and Innovation Center, Fondazione Edmund Mach, San Michele all'Adige, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Salamini
authors.affiliation: Research and Innovation Center, Fondazione Edmund Mach, San Michele all'Adige, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Velasco
authors.affiliation: Wageningen UR Plant Breeding, Wageningen University and Research Centre, Wageningen, The Netherlands.
authors.forename: Henk J
authors.initials: HJ
authors.lastname: Schouten
authors.affiliation: Research and Innovation Center, Fondazione Edmund Mach, San Michele all'Adige, Italy. Mickael.malnoy@fmach.it.
authors.forename: Mickael
authors.initials: M
authors.lastname: Malnoy
mesh_terms: D001203:Ascomycota / Q000502:physiology*; D060467:Disease Resistance / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D055785:Gene Knockdown Techniques; D027845:Malus / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000382:microbiology*; D034622:RNA Interference
chemical_list: D010940:Plant Proteins
keywords: Arabidopsis thaliana; MLO; Malus domestica; RNA interference; powdery mildew