Session 5: Variety Development and Host Resistance

One of the greatest problems in breeding for Fusarium head blight (FHB) resistance lies in the difficulty of assessing the disease. Air separation methods have long been used in the seed industry for seed conditioning purposes and in seed labs to measure the proportion of different components of seed samples. An air separation machine was specifically developed from a Precision Machine head thresher and a Shop-Vac vacuum to separate scabby kernels from healthy ones. Once a sample is loaded into the machine, air-driven elevation of the lighter portion of wheat (i.e. scabby seeds) occurs until it reaches the top of the column where is collected in a receptacle. The heavier portion of wheat (i.e. asymptomatic seeds) is suspended midair and does not reach the top of the column. Once the air is turned off, the asymptomatic seeds fall and are collected in the bottom of the column. Finally, both portions of the sample are weighed separately and FDK is calculated. Time per sample is about a minute. A population of 128 F3:4 and 48 F2:4 lines derived from a cross between FHB-susceptible KY93C-123817-2 and FHB-resistant VA01W476 were grown in headrows in October 2007 in scab nurseries located at Lexington and Princeton, KY. In 2008, scab ratings were recorded in the field; percentage of Fusarium damaged kernels (FDK) and deoxynivalenol (DON) concentration was measured in kernels harvested from headrows. FDK was measured using the air separation machine and DON was determined by GC-MS. The correlation between FDK and DON using all data points was 0.852, indicating that FDK measured by air separation can be a highly useful way to assess FHB in scab breeding programs. ACKNOWLEDGEMENT AND DISCLAIMER This material is based upon work supported by the U.S. Department of Agriculture under Agreement No. 590790-4-127. This is a cooperative project with the U.S.Wheat & Barley Scab Initiative. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.