PHYSIOCHEMICAL CHARACTERIZATION AND FIELD ASSESSMENT OF LETTUCE CHLOROSIS VIRUS

Lettuce chlorosis virus (LCV) was purified and partially characterized , and polyclonal antisera were produced and used to assess disease in the field. The antisera reliably detected LCV by indirect enzyme-linke d immunosorbent assay (ELISA) in Nicotiana benthamiana. In Western blo ts, the LCV antisera distinguished between LCV and lettuce infectious yellows virus (LIYV)-infected plants. LCV particle lengths in partiall y purified preparations, as observed by transmission electron microsco py, were variable, with the majority between 750 and 950 nm long. A si ngle, high molecular weight dsRNA and several lower molecular weight d sRNAs were isolated from LCV-infected N. benthamiana. A single RNA iso lated from purified virion preparations was estimated to be 8,625 nucl eotides long and was suspected to be the genomic RNA of LCV. LCV was p resent in experimental field plots in Holtville, California, during th e lettuce growing seasons of 1995 to 1997. The percentage of symptomat ic plants and yield of lettuce heads treated with insecticide, as well as dsRNA and ELISA reactions for the plots, are reported. A dsRNA con sistent in size with LCV was isolated from four weed species in the Im perial Valley of California.