Pathogenesis of tomato spotted wilt virus in peanut plants dually infected with peanut mottle virus

Peanut (Arachis hypogaea) plants dually infected with tomato spotted wilt tospovirus (TSWV) and peanut mottle potyvirus (PMV) exhibited a wide variety of symptoms, ranging from PMV-like symptoms of transient mild leaf mottle to TSWV-like symptoms of severe leaf distortion and stunting of the plant. Dual infection did not cause greater symptom severity than infection with either virus alone. In the early stages of disease development, PMV symptoms were similar to the first leaf symptoms of TSWV infection, suggesting that identification of TSWV in field-grown peanuts should not depend on visual observation. The virus titer, determined by enzyme-linked immunosorbent assay, indicated a delay in TSWV disease progress in double-infected plants, compared to plants infected with TSWV alone. In the later phase of disease progress, the virus titer in dually infected plants was not significantly different from that of singly infected plants. Infection with TSWV and PMV alone and with both viruses in combination was consistent among commercially grown peanut cultivars. In plants inoculated with TSWV or PMV alone or with both viruses in combination, the length of the latent period and final disease incidence, as measured by the number of plants showing symptoms, did not depend on the cultivar.