Open AccessThe knock‐down of the expression of MdMLO19 reduces susceptibility to powdery mildew ( Podosphaera leucotricha ) in apple ( Malus domestica )
Author(s) -
Pessina Stefano,
Angeli Dario,
Martens Stefan,
Visser Richard G.F.,
Bai Yuling,
Salamini Francesco,
Velasco Riccardo,
Schouten Henk J.,
Malnoy Mickael
Publication year - 2016
Publication title -
plant biotechnology journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.525
H-Index - 115
eISSN - 1467-7652
pISSN - 1467-7644
DOI - 10.1111/pbi.12562
Subject(s) - powdery mildew , biology , locus (genetics) , genetics , gene , mildew , mutant , arabidopsis thaliana , plant disease resistance , complementation , phenotype , botany
Summary 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 Md MLO 11 and 19 (clade V) and Md MLO 18 (clade VII ). We report the knock‐down through RNA interference of Md MLO 11 and 19 , as well as the complementation of resistance with Md MLO 18 in the Arabidopsis thaliana triple mlo mutant Atmlo2/6/12 . The knock‐down of Md MLO 19 reduced PM disease severity by 75%, whereas the knock‐down of Md MLO 11, alone or in combination with Md MLO 19, did not result in any reduction or additional reduction of susceptibility compared with Md MLO 19 alone. The test in A. thaliana excluded a role for Md MLO 18 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, Md MLO 19 plays the pivotal role in apple PM susceptibility and its knock‐down induces a very significant level of resistance.