Symptomless infection of barley seed by Rhynchosporium secalis
2001
Lee, H.K. | Tewari, J.P. | Turkington, T.K.
Rhynchosporium secalis, causal agent of scald of barley, generally overwinters in barley residues. However, the pathogen can also infect seeds, producing typical scald symptoms. In the present study, symptomless seed-infection by R. secalis was demonstrated, using both cultural and polymerase chain reaction (PCR)-based detection assays. Seeds of the cv. Harrington without visible scald lesions were plated on lima bean agar supplemented with Bengal rose and streptomycin. In six independent trials, about 14% of seeds gave rise to colonies of R. secalis. A species-specific primer set, based on sequence analysis of the internal transcribed spacer regions of R. secalis, was also used to detect symptomless seed-infection. The primer set did not amplify the R. secalis diagnostic band in seed DNA extracts of the resistant cv. Seebe, but the scald pathogen was detected in symptomless seed DNA extracts of the susceptible cv. Harrington. The results indicated that appreciable symptomless seed-infection by R. secalis can occur in barley and that diagnostic methods such as cultural and PCR-based assays would be useful to monitor it.
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