Unravelling The Molecular Basis Of An Old Enemy: Cmv Resistance In Melon (Cucumis Melo L.)

The study of the complex resistance to Cucumber mosaic virus (CMV) present in the Korean melon accession 'Sonwang Charmi, PI 161375' (SC) has been addressed using two melon populations, a near isogenic line (NIL) collection and a dihaploid line (DHL) collection, both generated from a cross between SC as resistant parental line and the cultivar Piel de Sapo (PS) as susceptible parental line. Previously, the NIL collection allowed us to describe a single recessive gene, cmv1, which confers full resistance to CMV strains P9 and P104.82, but not to strains M6 and TL. Screening of the whole DHL population followed by QTL analysis revealed that the genetic control of the resistance to the strains M6 and TL is complex and requires the involvement of three QTLs that interact, one of them probably being cmv1 itself. Therefore, the resistance to CMV in melon SC is qualitative for some strains and quantitative for others. For this later resistance, cmv1 is necessary and explains most of the phenotypic variance, but is not sufficient, and needs the interaction with the other two loci. The molecular cloning of the major gene, cmv1, has progressed up to an interval of 140 Kb.