Interviral Recombination between Plant, Insect, and Fungal RNA Viruses: Role of the Intracellular Ca 2+ /Mn 2+ Pump

Viruses with RNA genomes are abundant, and their genomic sequences show astonishing variation. Genetic recombination in RNA viruses is a major force behind their rapid evolution, enhanced pathogenesis, and adaptation to their hosts. We utilized a previously identified intracellular Ca2+ /Mn2+ pump-deficient yeast to search for interviral recombinants. Noninfectious viral replication systems were used to avoid generating unwanted infectious interviral recombinants. Altogether, interviral RNA recombinants were observed between plant and insect viruses, and between a fungal double-stranded RNA (dsRNA) virus and an insect virus, in the yeast host. In addition, interviral recombinants between two plant virus replicon RNAs were identified inN. benthamiana plants, in which the intracellular Ca2+ /Mn2+ pump was depleted. These findings underline the crucial role of the host in promoting RNA recombination among unrelated viruses.