Archivio Journal of Plant Pathology

Abstract:

Northwestern Brazil is a major center of diversity for cactaceous plants, most of which are grown as ornamentals. Cactus virus X (CVX), the only virus reported so far from Brazilian cactaceae, is widely spread. In this study we have characterized viruses of Opuntia tuna (OT), Hylocereus undatus (HU) and Schlumbergera truncata (ST) from the State of São Paulo, showing chlorotic spots and mosaic symptoms. Mechanically inoculated Gomphrena globosa reacted with local lesions, except when OT extracts were used as inoculum, whereas Chenopodium amaranticolor showed erratic systemic symptoms following inoculations from HU and ST. Transmission electron microscopy showed flexuous particles ca. 550 nm in length and bundles of virus particles in leaf cells from naturally and experimentally infected plants. Virus particles reacted faintly with an antiserum to CVX. Nucleotide sequences of the RNA dependent RNA polymerase gene obtained from cloned RT-PCR products, revealed the occurrence of Zygocactus virus X (ZyVX) in OT, mixed infection by ZyVX and Schlumbergera virus X (SchVX) in HU, and mixed infection by ZyVX, SchVX and Opuntia virus X (OpVX) in ST. This is the first report of ZyVX, SchVX and OpVX in Brazil.