Reaction of durum wheat cultivars to mixed SBWMV and WSSMV infection in central Italy

Abstract

Forty-three cultivars of durum wheat (Triticum durum Desf.) were grown during the 1998–99 growing season in a field near Rome with natural inoculum sources of Soilborne wheat mosaic virus (SBWMV) and Wheat spindle streak mosaic virus (WSSMV), to evaluate their resistance to the mixed infection. Leaf extracts from twelve cultivars had relatively low ELISA values for WSSMV, and thirteen had low ELISA values for SBWMV. Results confirmed the high level of resistance to SBWMV of the cultivars Colorado, Ionio and Neodur. The reactions of the cultivars to SBWMV were consistent with those recorded in previous trials near Bologna, northern Italy, indicating that the SBWMV strains at the two test sites were pathogenically similar. Disease severity was significantly correlated with grain yield, thousand-kernel weight, heading date and the SBWMV-ELISA value, but not with the WSSMVELISA value. Regression analysis showed that, as a result of the mixed infection, the four cultivars with the most severe disease symptoms headed about 5 days later than normal, and suffered grain yield and kernel weight reductions of about 56 and 10% respectively. Cultivars with milder symptoms were also severely affected.