The occurrence of barley mild mosaic virus (BaMMV) in China and the nucleotide sequence of its coat protein gene

Barley mild mosaic bymovirus (BaMMV) was detected in 1991, 1992, 1996 and 1997 by enzyme-linked immunosorbent assay and immunosorbent electron microscopy in barley (Hordeum vulgare) from three sites in China (Rudong, Yancheng and Haian). The virus was always present with barley yellow mosaic bymovirus (BaYMV) in the Chinese BaYMV-susceptible cultivar Yanfuaizhao 3, but was not detected in 14 European and two Japanese cultivars that were tested. Electrophoresis of viral RNA and immunoblot analysis indicated that the Chinese isolate of BaMMV contained two RNAs (7.3 and 3.5 kb) and a single coat protein of approximately 33 kDa. The coat protein gene of the virus was amplified by reverse transcriptase (RT)-polymerase chain reaction (PCR), cloned into the pBluescript (13 +) vector and sequenced. It was identical in length (753 nucleotides; 251 amino acids) to that of isolates from Japan, Korea, Germany, France and the UK. Its homology with the other isolates was 87.8 to 95.2% (nucleotides) and 91.8 to 97.6% (amino acids), and the isolate was most similar to those from Korea and Japan. The results confirmed that the virus detected in China was indeed BaMMV and suggested also that a specific strain of BaMMV has long been established in China.