Response of Tall Fescue Genotypes to a New Strain of Brome mosaic virus.

Brome mosaic virus (BMV) infects many different species within the Poaceae family. A new strain of BMV, named F-BMV, was identified in a tall fescue (Festuca arundinacea Schreb.) plant. Here, we report the identification and characterization of tall fescue plants resistant to F-BMV, and the effects of F-BMV infection on their growth and development. Susceptible plants infected with F-BMV produced 40% fewer tillers and 42% less dry matter compared with virus-resistant plants in a greenhouse study. In the field, susceptible plants infected with F-BMV produced 25% fewer tillers, 36% less dry matter, 10% less plant height, and 40% lower seed yield compared with virus-resistant plants. In a field evaluation of a tall fescue mapping population, the virus symptom scores were negatively correlated with production of dry matter (r = -0.55), plant height (r = -0.55), and seed yield (r = -0.33). Thus, F-BMV has the potential to cause significant economic damage to susceptible tall fescue plants. These results indicate that the virus can present a serious challenge for long-term maintenance of valuable plant materials. A survey of tall fescue plants from Arkansas, Oklahoma, and Oregon indicated that the prevalence F-BMV in the field was very low.