Resistance to watermelon mosaic virus (WMV) was transferred by success
ive backcrossing with selection from Cucumis melo PI 414723 to three m
elon varieties. Levels of resistance to virus accumulation in leaf tis
sue were evaluated using enzyme-linked immunosorbent assay, and proced
ures are described to select resistant individuals efficiently and acc
urately in segregating populations. Resistance is controlled by a sing
le dominant gene designated Wmr. Plants that carry this gene initially
develop mosaic symptoms on inoculated leaves, but eventually recover
from symptoms, and low or no virus can be detected in the youngest lea
ves. In contrast, susceptible plants show similar symptoms initially,
but remain stunted and symptomatic with reduced fruit yield and fruit
quality. Co-infection with other cucurbit viruses, specifically cucumb
er mosaic virus, papaya ringspot virus, and zucchini yellow mosaic vir
us, did not overcome resistance to WMV conferred by Wmr.