USE OF IMMUNOLOGICAL METHODS WITH ANTIRIBOSOME SERA TO DETECT SNOW MOLD FUNGI IN WHEAT PLANTS

Ribosomal protein differences among snow mold fungi and wheat were utilized to detect the causal fungi in infected wheat leaves by indirect enzyme-linked immunosorbent assay (ELISA) and western blot analysis. Polyclonal antiserums were raised against the ribosomes of Pythium paddicum, P. iwayamai, Typhula incarnata, and Microdochium nivale and tested for sensitivity and specificity with ribosomes of these four pathogens, Typhula ishikariensis, and wheat. Using polyclonal antiserums, ribosomes of P. paddicum and P. iwayamai were serologically identical; the ribosomes of T incarnata and T. ishikariensis had partial common antigenic determinants, but there were apparent serological differences among Pythium spp., Typhula spp., M. nivale, and wheat. With indirect ELISA, ribosomes of Pythium spp. were detectable at a concentration of 69 ng/ ml and ribosomes of T. incarnata and M. nivale at a concentration of 210 ng/ml. The ribosomes of each target pathogen were detected from completely rotted wheat leaf homogenates diluted up to 1:1,000 or 1:10,000. The indirect ELISA could not differentiate P. paddicum from P. iwayamai-infected plants or T incarnata from T. ishikariensis-infected plants but could detect and differentiate snow mold fungi at the genus level in wheat plants. Western blot analysis with these antiserums also could not differentiate P. paddicum from P. iwayamai but could differentiate wheat leaves infected with T incarnata from those infected with T ishikariensis. These immunological methods with antiribosome serums would be useful to evaluate wheat plants for infection by Pythium spp., T. incarnata, T ishikariensis, and M. nivale.