Culture conditions influence conidial production by the barley pathogen Ramularia collo-cygni

Abstract

The fungus Ramularia collo-cygni is the causal agent of the Ramularia leaf spot (RLS) disease of barley (Hordeum vulgare). Despite having been described over 100 years ago, our knowledge of the life cycle and epidemic development of R. collo-cygni is limited. To learn more about its epidemiology, inoculation techniques are among the major research needs since standardised inoculation procedures must be available to mimic natural infection of the pathogen under controlled conditions. The present study was conducted to obtain an insight into various factors affecting the growth and sporulation of R. collo-cygni in axenic culture. The fungus was cultured on four different media and subjected to two light regimens to determine conditions favourable for its growth and sporulation. We showed that conidial production can be enhanced by growing R. collo-cygni on barley straw agar, a medium that mimics the plant host, under white light, or on quarter-strength potato dextrose agar supplemented with V8 juice agar under ultraviolet-C light, depending on the fungal isolate. To verify the infection potential of the spores produced in axenic culture, an inoculation trial was performed. R. collo-cygni spore-inoculated barley plants accumulated fungal biomass, demonstrating successful infection.