CHARACTERIZATION AND COMPARISON OF PASSIONFRUIT MOTTLE VIRUS, A NEWLY RECOGNIZED POTYVIRUS, WITH PASSIONFRUIT WOODINESS VIRUS

A virus, designated passionfruit mottle virus (PaMV), was isolated from plants of passionfruit cultivar Tainung No. 1, which showed mild mottling. Unlike the previously described passionfruit woodiness virus (PWV), PaMV does not induce severe foliage mosaic and woody, misshapen fruits. It was identified as a potyvirus on the basis of particle morphology, aphid transmissibility, and the ability to induce cytoplasmic cylindrical inclusions (CI) in infected cells. Of 25 plant species inoculated, 11 (Nicotiana benthamiana, four passiflora species, and six leguminous species) developed differential reactions. Two bean cultivars (i.e., Sutter pink and Dubbele witte) resistant to PWV were susceptible to PaMV, whereas another cultivar, Black turtle, which is resistant to PaMV, was systemically infected with PWV. PaMV induced bundle-shaped CIs in the cytoplasm of infected cells; PWV induced short platelike CIs. Purified virions and the cylindrical inclusion proteins (CIPs) of PaMV were obtained by isopycnic centrifugation and preparative electrophoresis, respectively. Antisera against intact virions and CIPs of PaMV and PWV were prepared for the comparison of antigenic properties. In reciprocal sodium dodecyl sulfate immunodiffusion tests and direct enzyme-linked immunosorbent assays, PaMV was shown to be antigenically related to, but distinct from, PWV, bean common mosaic, blackeye cowpea mosaic, watermelon mosaic 2, and soybean mosaic viruses, but was unrelated to 12 other potyviruses tested in the study.