Monday, November 13, 2006

ELISA Analysis for Fusarium in Barley: Application in Field Nurseries.

Nicholas Hill, Univ of Georgia, Dept. Crop & Soil Sciences, 3111 Miller Plant Sci. Bldg., Athens, GA 30602, Stephen Neate, North Dakota State Univ., Dept. of Plant Pathology, Fargo, ND 58105, Blake Cooper, Busch Agriculturual Resources Inc., E. Richards Lake Rd., Ft. Collins, CO 80524, Richard Horsley, Dept. of Plant Science, North Dakota State Univ., PO Box 5051, Fargo, ND 58105-5051, Paul Schwarz, PO Box 5728, 1250 Bolley Dr., North Dakota State University, North Dakota State University, Department of Cereal Science, Fargo, ND 58105-5728, Lynn Dahleen, State University Station, USDA-ARS-NPA-SPNRU, USDA-ARS Northern Crop Science Lab, PO Box 5677, Fargo, ND 58105-5677, Kevin Smith, Dept. of Agronomy, Univ. of Minnesota, 411 Borlaug Hall, St. Paul, MN 55108, and Ruth Dill-Mackey, Dept. of Plant Pathology, Univ. of Minnesota, 495 Borlaug Hall, St. Paul, MN 55108.

Previously we described a system of quantifying Fusarium Head Blight (FHB) in barley by ELISA.  ELISA had lower variability (lower CV’s) than visual scoring or deoxynivalenol (DON) analyses.  Thus we tested ELISA, DON, and visual assessment of FHB in 1) selections from a barley doubled-haploid mapping population grown in two environments and 2) the North American barley scab evaluation nursery grown at four locations.  All methods of evaluation had genotype x environment interactions typically found in FHB experiments.  Correlations between FHB and DON or FHB and ELISA were significant, but low (r≤0.5).  Correlations between DON and ELISA were also significant but low (r≤0.6).  Scattergrams of visual vs. ELISA estimates of FHB suggest visual symptomology is not correlated with abundance of Fusarium on the grain, but samples low in ELISA were also low in DON.  We conducted laboratory experiments to explain how environmental parameters might affect DON and whether those parameters affected ELISA.  In addition we tested for abundance of the antigen specific to the monoclonal antibody used in the ELISA analysis.  There was a temperature by osmotic potential effect on DON production in laboratory-grown cultures of Fusarium spp.  Neither temperature nor osmotic potential had an effect on abundance of antigen in mycelium.  Therefore, ELISA is a more robust estimate of FHB than DON.