Occurrence of Barley mild mosaic virus on Barley in Spain

Abstract

Mosaic and yellowing symptoms were observed on winter barley during March of 2002 in northeastern Spain. Symptoms were similar to those caused by Barley yellow mosaic virus (BaYMV) and Barley mild mosaic virus (BaMMV), members of the genus Bymovirus (family Potyviridae). Leaves from 17 samples of barley were analyzed by enzyme-linked immunosorbent assay (ELISA) using antisera specific for BaYMV (Bio-Rad Laboratories, Hercules, CA) and BaMMV (Loewe Biochemica, Munich). Five samples tested positive with the BaYMV antiserum, and two samples were positive with the BaYMV and BaMMV antisera. Ranges of ELISA values were from 3.8 to 13 times higher than the negative controls with the BaYMV antiserum and from 18 to 21 times higher with the BaMMV antiserum. Mixed infections were further analyzed by reverse transcription-polymerase chain reaction (RT-PCR) using specific primers that amplify 433 bp of BaYMV (1) and 445 bp of BaMMV coat protein gene (primer 1: 5′GCG TCC GTT GCA ACT GA 3′ and primer 2: 5′GAA TTG CTT GTG CCA ACA 3′. A PCR product of the expected size was observed with BaMMV primers but not with BaYMV primers. The sequence of BaMMV PCR product was determined and compared with that of the equivalent regions of other BaMMV isolates (Genbank Accession Nos. AJ242725, AJ224872, D83410, D83408, L49381, Y10973, and Y10974). The greatest nucleotide identity (96 to 98%) was found with isolates from Germany and Italy, followed by those from France and the United Kingdom (89%), and the lowest identity being with isolates from Asia (85 to 88%). The BaYMV presence needs to be confirmed. To our knowledge, this is the first report of a bymovirus infecting barley in Spain, and illustrates the continuing spread within Europe of viruses vectored by Polymyxa graminis Led. Reference: (1) D. Hariri et al. Eur. J. Plant Pathol. 106:365, 2000.