title: Knockdown of MLO genes reduces susceptibility to powdery mildew in grapevine.
abstract: Erysiphe necator is the causal agent of powdery mildew (PM), one of the most destructive diseases of grapevine. PM is controlled by sulfur-based and synthetic fungicides, which every year are dispersed into the environment. This is why PM-resistant varieties should become a priority for sustainable grapevine and wine production. PM resistance can be achieved in other crops by knocking out susceptibility S-genes, such as those residing at genetic loci known as MLO (Mildew Locus O). All MLO S-genes of dicots belong to the phylogenetic clade V, including grapevine genes VvMLO7, 11 and 13, which are upregulated during PM infection, and VvMLO6, which is not upregulated. Before adopting a gene-editing approach to knockout candidate S-genes, the evidence that loss of function of MLO genes can reduce PM susceptibility is necessary. This paper reports the knockdown through RNA interference of VvMLO6, 7, 11 and 13. The knockdown of VvMLO6, 11 and 13 did not decrease PM severity, whereas the knockdown of VvMLO7 in combination with VvMLO6 and VvMLO11 reduced PM severity up to 77%. The knockdown of VvMLO7 and VvMLO6 seemed to be important for PM resistance, whereas a role for VvMLO11 does not seem likely. Cell wall appositions (papillae) were present in both resistant and susceptible lines in response to PM attack. Thirteen genes involved in defense were less upregulated in infected mlo plants, highlighting the early mlo-dependent disruption of PM invasion.
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 Centre, PO Box 386, 6700 AJ Wageningen, The Netherlands.
authors.forename: Stefano
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; Department of Ecological and Biological Sciences, Università della Tuscia, Via San Camillo de Lellis, Viterbo 01100, Italy.
authors.forename: Luisa
authors.initials: L
authors.lastname: Lenzi
authors.affiliation: Research and Innovation Centre, Fondazione Edmund Mach , via Edmund Mach 1, 38010 San Michele all'Adige, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Perazzolli
authors.affiliation: Research and Innovation Centre, Fondazione Edmund Mach , via Edmund Mach 1, 38010 San Michele all'Adige, Italy.
authors.forename: Manuela
authors.initials: M
authors.lastname: Campa
authors.affiliation: Research and Innovation Centre, Fondazione Edmund Mach , via Edmund Mach 1, 38010 San Michele all'Adige, Italy.
authors.forename: Lorenza
authors.initials: L
authors.lastname: Dalla Costa
authors.affiliation: Council for Agricultural Research and Economics (CREA), Rice Research Unit, S.S. 11 per Torino km 25, Vercelli 13100, Italy; Council for Agricultural Research and Economics (CREA), Genomics Research Centre, Via San Protaso, 302, 29017, Fiorenzuola d'Arda, Piacenza, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Urso
authors.affiliation: Council for Agricultural Research and Economics (CREA), Rice Research Unit, S.S. 11 per Torino km 25, Vercelli 13100, Italy; Council for Agricultural Research and Economics (CREA), Genomics Research Centre, Via San Protaso, 302, 29017, Fiorenzuola d'Arda, Piacenza, Italy.
authors.forename: Giampiero
authors.initials: G
authors.lastname: Valè
authors.affiliation: Research and Innovation Centre, Fondazione Edmund Mach , via Edmund Mach 1, 38010 San Michele all'Adige, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Salamini
authors.affiliation: Research and Innovation Centre, Fondazione Edmund Mach , via Edmund Mach 1, 38010 San Michele all'Adige, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: 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