2.1. Plant, Insects and Virus Materials

The melon (Cucumis melo) genotypes used in this study were the Korean accession PI 161375, cultivar Songwhan Charmi, the Spanish type Piel de Sapo, and the NIL SC12-1-99, which carries an introgression of SC on the linkage group XII that contains the cmv1 gene [8]. Seeds were pre-germinated and grown as described by Guiu-Aragonés et al. [11].

A clonal population of the aphid Myzus persicae, designated MP89 and originally from the ICA-CSIC (Madrid, Spain), was maintained on tobacco plants (Nicotiana tabacum ‘Xanthi’).

The cucumovirus strain CMV-LS was provided by Professor P. Palukaitis from Seoul’s Women’s University (Korea) as infectious clones of the three genomic RNAs [24]. The potyviruses ZYMV-AGII (attenuated strain) and watermelon mosaic virus LL2B3 (WMV-LL2B3) infectious clones were provided by Prof. A. Gal-On from Volcani Center (Israel) [25] and Dr. C. Desbiez from INRAE (France) [26], respectively.