RT-PCR detection of seedborne Cowpea aphid-borne mosaic virus in peanut

The Brazilian strain of Cowpea aphid-borne mosaic virus (CABMV) is a severe pathogen in peanut and a significant problem when distributing germ plasm to other countries. The virus is seedborne at approximately 0.15% in peanut , depending upon the cultivar, and its detection in seed lots would strengt hen quarantine programs. Utilizing 3' sequence data (GenBank Accession #AF2 41233), primers were designed from the coat protein region and evaluated by reverse transcription-polymerase chain reaction (RT PCR). Use of the forwa rd primer 5'-CGCTCAAACCCATTGTAGAA-3' and reverse primer 5'-TATTGCTTCCCTTGCT CTTTC-3' yielded a 221-bp product. Extracts of thick seed slices and a samp le size of 12 to 25 seed showed no significant advantage of RT PCR over enz yme-linked immunosorbent assay (ELISA) in tests of large seed lots. However , RT PCR detected more virus in seed than in the number of infected seedlin gs normally arising in germination tests. Also, RT PCR was extremely sensit ive and detected 1 infected leaf among 99 healthy leaves. In contrast, ELIS A detected only one infected leaf among nine healthy leaves.