title: Frequency of a natural truncated allele ofMdMLO19in the germplasm ofMalus domestica.
abstract: Podosphaera leucotrichais the causal agent of powdery mildew (PM) in apple. To reduce the amount of fungicides required to control this pathogen, the development of resistant apple cultivars should become a priority. Resistance to PM was achieved in various crops by knocking out specific members of theMLOgene family that are responsible for PM susceptibility (S-genes). In apple, the knockdown ofMdMLO19resulted in PM resistance. However, since gene silencing technologies such as RNAi are perceived unfavorably in Europe, a different approach that exploits this type of resistance is needed. This work evaluates the presence of non-functional naturally occurring alleles ofMdMLO19in apple germplasm. The screening of the re-sequencing data of 63 apple individuals led to the identification of 627 single nucleotide polymorphisms (SNPs) in fiveMLOgenes (MdMLO5, MdMLO7, MdMLO11, MdMLO18, andMdMLO19), 127 of which were located in exons. The T-1201 insertion of a single nucleotide inMdMLO19caused the formation of an early stop codon, resulting in a truncated protein lacking 185 amino acids, including the calmodulin-binding domain. The presence of the insertion was evaluated in 115 individuals. It was heterozygous in 64 and homozygous in 25. Twelve of the 25 individuals carrying the insertion in homozygosity were susceptible to PM. After barley, pea, cucumber, and tomato, apple would be the fifth species for which a natural non-functionalmloallele has been found.
authors.affiliation: Research and Innovation Centre, Fondazione Edmund Mach, Via Edmund Mach 1, 38010 San Michele all'Adige, Italy.|Wageningen UR Plant Breeding, Wageningen University and Research, P.O. Box 386, 6700 AJ Wageningen, the Netherlands.
authors.forename: Stefano
authors.identifier: 0000-0001-5109-0593
authors.initials: S
authors.lastname: Pessina
authors.affiliation: Research and Innovation Centre, Fondazione Edmund Mach, Via Edmund Mach 1, 38010 San Michele all'Adige, Italy.
authors.forename: Luisa
authors.initials: L
authors.lastname: Palmieri
authors.affiliation: Research and Innovation Centre, Fondazione Edmund Mach, Via Edmund Mach 1, 38010 San Michele all'Adige, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Bianco
authors.affiliation: Agroscope, Institute for Plant Production Sciences IPS, Schloss 1, 8820 Wädenswil, Switzerland.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Gassmann
authors.affiliation: Wageningen UR Plant Breeding, Wageningen University and Research, P.O. Box 386, 6700 AJ Wageningen, the Netherlands.
authors.forename: Eric
authors.initials: E
authors.lastname: van de Weg
authors.affiliation: Wageningen UR Plant Breeding, Wageningen University and Research, P.O. Box 386, 6700 AJ Wageningen, the Netherlands.
authors.forename: Richard G F
authors.initials: RGF
authors.lastname: Visser
authors.affiliation: Research and Innovation Centre, Fondazione Edmund Mach, Via Edmund Mach 1, 38010 San Michele all'Adige, Italy.
authors.forename: Pierluigi
authors.initials: P
authors.lastname: Magnago
authors.affiliation: Wageningen UR Plant Breeding, Wageningen University and Research, P.O. Box 386, 6700 AJ Wageningen, the Netherlands.
authors.forename: Henk J
authors.initials: HJ
authors.lastname: Schouten
authors.affiliation: Wageningen UR Plant Breeding, Wageningen University and Research, P.O. Box 386, 6700 AJ Wageningen, the Netherlands.
authors.forename: Yuling
authors.initials: Y
authors.lastname: Bai
authors.affiliation: Research and Innovation Centre, Fondazione Edmund Mach, Via Edmund Mach 1, 38010 San Michele all'Adige, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Riccardo Velasco
authors.affiliation: Research and Innovation Centre, Fondazione Edmund Mach, Via Edmund Mach 1, 38010 San Michele all'Adige, Italy.
authors.forename: Mickael
authors.initials: M
authors.lastname: Malnoy
keywords: Apple; MLO; Malus domestica; MdMLO19; Powdery mildew; SNP