Watermelon Mosaic Virus and Zucchini Yellow Mosaic Virus

Abstract

Watermelon mosaic virus (WMV) and zucchini yellow mosaic virus (ZYMV) are two major potyviruses infecting cucurbits. WMV is the causal agent of one of the first described cucurbit mosaic virus diseases, while ZYMV emerged as a major cucurbit pathogen causing severe yield losses only in the late 1970s. WMV infects many weeds and several crops outside cucurbits while ZYMV has a more restricted host range. Both are efficiently transmitted by aphids in a nonpersistent manner, which often results in rapid and severe epidemics in the fields. Control measures rely mainly on prophylactic methods (weeding, mulching). Cross-protection has been developed commercially to control severe ZYMV isolates. Breeders using classical and genetically engineered resistance have already released WMV and ZYMV commercial resistant cultivars in the major cucurbit crops. Important biological variability is observed among ZYMV isolates and to a lesser extent among WMV isolates. The serological and molecular variability is also high. Molecular studies revealed that WMV probably arose through recombination between two legume-infecting viruses. In addition, intraspecific recombinations seem to be common in WMV. ZYMV is presently used as a biotechnological tool to produce in cucurbit plants proteins of pharmaceutical or plant protection interest.