Expression of resistance to barley stripe mosaic virus in barley and oat protoplasts.

Mesophyll protoplasts from both susceptible and resistant hosts were inoculated with RNA purified from barley stripe mosaic virus (BSMV) strains CV52 and CV42 using the polyethylene glycol (PEG) method. Protoplasts derived from the susceptible Hordeum vulgare L. cv. Black Hulless were susceptible to both BSMV strains, as indicated by fluorescein isothiocyanate staining and ELISA. More than 80% of protoplasts derived from an oat cultivar resistant to CV52, but not to CV42, were readily infected by either CV52 or CV42. Protoplasts from 10 barley lines resistant to CV42 remained resistant to CV42, although a limited number of protoplasts were infected. Functional resistance in the cultured barley protoplasts, but not in those from oat plants, suggests that resistance in these barley lines may be the result of restriction of replication, whereas resistance in oat plants is more likely due to restriction of cell-to-cell movement.