Infection of Cowpea Mesophyll Protoplasts with Clover Yellow Mosaic Virus

Several factors were investigated in relation to infection and multiplication of clover yellow mosaic virus (CYMV) in cowpea mesophyll protoplasts. The extent of virus multiplication was determined by fluorescent antibody staining and infectivity assay. The conditions that gave the most infection (38%) were: preincubation of the virus with 0.4 µg/ml poly-l-ornithine, a virus concentration of 4 µg/ml, an inoculum containing citrate buffer at pH 6.0, and contact between inoculum and protoplasts for at least 15 min. Time-course studies revealed synchronous one-step growth of virus with rapid accumulation of virus antigen from 12 to 48 h after inoculation.