COAT PROTEIN SEQUENCES OF RMV-LIKE STRAINS OF BARLEY YELLOW DWARF VIRUS SEPARATE THEM FROM OTHER LUTEOVIRUSES

Illinois (IL) and Minnesota (MN) RMV-like strains of barley yellow dwarf virus (BYDV) were identified from maize displaying red leaf symptoms by enzyme-linked immunosorbent assay (ELISA) using antiserum against a New York strain (BYDV-RMV-NY). Some IL and MN strains, but not the NY strain, could be detected by ELISA with a monoclonal antibody raised against BYDV-RPVNY. The region of the viral genome representing the coat protein gene was amplified by polymerase chain reaction, cloned and sequenced. The nucleotide sequences of the BYDV-RMV-IL and BYDV-RMV-MN coat protein genes differed at just five nucleotide positions while the BYDV-RMV-IL and BYDV-RMV-NY differed at 101 of the 591 positions. The predicted amino acid sequences of the coat proteins of RMV-like strains from IL, MN, and NY shared approximately 60% identity with those of the coat proteins of beet western yellows virus, BYDV-RPV-NY, and potato leafroll virus.