Extensive surveys were conducted in Washington State during a 6-yr period between 1988 and 1994 in an attempt to locate reservoirs of pea enation mosaic virus (PEMV). Many of the peas (Pisum sativum L.), chickpeas (Cicer arietinum L.), lentils (Lens culinaris Medic), or faba beans (Vicia faba L.) collected during the survey, and which expressed symptoms of virus infection, tested positive for PEMV when assayed by double antibody sandwich enzyme-linked immunosorbent assay (ELISA). PEMV could not, however, be detected by ELISA in any of 3230 alfalfa samples collected from eight counties in Washington State, even when samples were taken from alfalfa fields adjacent to infected pea, lentil, or chickpea fields where the virus was present. Dot blot hybridizations using a 4556 nucleotide cDNA fragment of PEMV RNA 1 containing the coat protein region produced strong reactions with positive controls, and did not detect the virus in 597 alfalfa samples tested in 1994. Fifty-six attempts to transmit PEMV into and out of alfalfa by aphid and mechanical transmissions were unsuccessful, while successful transmissions to and from pea and faba bean, or chickpea were made routinely. Our inability to detect PEMV in, or transmit the virus to alfalfa suggests that alfalfa is not currently a host. The overwintering epidemiologically significant reservoir host(s) of PEMV in the Pacific Northwest remains unknown. Key words:Medicago sativa L., legumes, virus survey, pea enation mosaic virus
Molecular characterization of two sugarcane streak mosaic virus isolates from Iran with emphasis on its population structure
