Radioimmunosorbent Assay for Detection of Lettuce Mosaic Virus in Lettuce Seed. S. A. Ghabrial, Visiting Professor, Department of Plant Pathology, University of California, Davis 95616. Debao Li, Visiting Scientist, and R. J. Shepherd, Professor, Department of Plant Pathology, University of California, Davis 95616. Plant Dis. 66:1037-1040. Accepted for publication 27 February 1982. Copyright 1982 American Phytopathological Society. DOI: 10.1094/PD-66-1037.

Reliability of radioimmunosorbent assay (RISA) or enzyme-linked immunosorbent assay (ELISA) for detection of lettuce mosaic virus in lettuce seed was improved by modification of the extraction medium. Addition of mannose and glucosamine to the conventionally used phosphate-buffered saline in the case of RISA, or the use of lower pH citrate buffer with diethyldithiocarbamate as an additive in the case of ELISA, reduced the nonspecific background that sometimes obscures specific reactions in these tests. Individual seed assayed by RISA showed a 15-fold variation in lettuce mosaic virus content. Blind testing of lettuce seed lots of known content of the virus showed that three infected seeds per 30,000 could be consistently detected by RISA when five to 10 sublots per seed lot were assayed.

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