Strains of Zucchini Yellow Mosaic Virus in Muskmelon (Cucumis melo L.)

According to the reaction of muskmelon line PI 414723, 22 natural isolates of Zucchini Yellow Mosaic Virus (ZYMV) were grouped into two pathotypes. When inoculated by isolates belonging to pathotype 0, most of the PI 414723 plants (over 70%) remained symptomless while few plants developed systemic chloronecrotic spotting and more rarely yellowing, stunting, mosaic and leaf deformations. When contaminated by pathotype 1 all PI 414723 plants developed systemic chloronecrotic spotting. Two variants were obtained from representative strains of these two pathotypes, able to induce yellowing, stunting, mosaic and leaf deformation on all inoculated PI 414723 plants. These variants could not be differentiated from their originating strains either by host range, serology or aphid transmission properties. Therefore they are regarded as belonging to a third group called pathotype 2. No relation was observed between the type of symptom developed on PI 414723 and the ability to induce a rapid wilting reaction of melon cv. Doublon (pathotype F).