Melon Virus Susceptibility and RDR Gene Mapping

Cucumis melo L. cvs. Arava and Vedrantais were used for CmRDR gene mapping and virus susceptibility analyses. In addition, in 10 melon genotypes (listed in Table S1) the truncated RDR1b genes were mapped. Seeds were planted in a soil mixture and grown in a greenhouse in daylight at 25 °C. The viruses listed in Table S2 were used for virus accumulation analysis and evaluation of RDR gene expression, namely: cucumber mosaic virus CMV—Fny strain, CMV mutant lacking the 2b gene (CMV-Δ2b) [36 (link)], CGMMV, CVYV, ZYMV, PRSV-W and WMV. Squash (Cucurbita pepo L. cv. Zuccini) plants were a source of inocula for PRSV-W, WMV and ZYMV. Cucumber (Cucumis sativus L. cv. Bet Alfa) plants were inocula sources for CMV, CMV-Δ2b, CGMMV and CVYV. Melon seedlings at the cotyledon stage with a small true leaf (about 3–5 days post-emergence) were dusted with carborundum (320 grit powder, Fisher Scientific, USA) before mechanical inoculation with virus-bearing sap (ca. 1:10 ratio g tissue/mL H₂O) [37 (link)].