First report of Barley yellow mosaic virus infecting barley in Poland

Barley yellow mosaic virus (BaYMV) is a dangerous pathogen of winter barley in Europe and Japan, transmitted by the plasmodiophorid vector Polymyxa graminis Led. (Adams, 1996).No data on the occurrence of barley yellow mosaic viruses were recorded in Poland until spring 2008. First disease symptoms appeared in at least 50% of winter barley fields by late March, affecting mainly cv. Vanessa in Lower Silesia region. These were associated with mosaic and leaf yellowing, including longitudinal chlorotic flecks on younger leaves of some plants, decreased growth, and irregular yellow patches in the fields.

Leaves of barley plants with symptoms were collected during April and May, and tested by ELISA using antibodies against BaYMV (Loewe, Germany), yielding positive results with 135 out of 352 samples. The OD values ranged from three to 10 times higher than the negative controls. Bymovirus-like flexuous particles, about 700 nm long, were observed under the electron microscope (Philips EM-201) in leaf extracts only from samples from symptom-bearing leaves .

Fourteen plant samples, found to be ELISA positive for BaYMV were indexed by reverse transcription–polymerase chain reaction (RT-PCR). Total RNA was isolated from 100-120 mg fresh plant tissue using RNeasy Mini Kit (Qiagen, Germany), reverse transcribed and then amplified by PCR using a one step RT-PCR kit (Qiagen) with primers BaYMV-F and BaYMV-R (Vaïanopoulos et al., 2003). PCR products of the expected size (346 bp) observed in nine samples were separated electrophoretically in a 1 % agarose gel. The consensus sequence from two amplicons was deposited in GenBank (FJ436987).The BaYMV partial coat protein sequence showed the highest identity (100%) with that of BaYMV from UK (AJ515485). The virus was easily propagated in glasshouse conditions by soil-transmission experiments. The identification of BaYMV in Poland is an important indication for barley growers to cultivate only resistant winter barley cultivars in the regions of the disease incidence.