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.