Submitted to: Brazilian Journal of Agricultural Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/1/2008
Publication Date: 11/1/2008
Citation: De. Fraias Neto, A.L., Schmidt, M., Hartman, G.L., Li, S., Diers, B.W. 2008. Greenhouse Inoculation Methods for Evaluating Resistance of Soybean to Sudden Death Syndrome. Brazilian Journal of Agricultural Research. 43:1475-1482. Interpretive Summary: Sudden death syndrome (SDS) is a soybean disease caused by a soil borne fungus. One method to control this disease is to select and breed for resistance. Selection for SDS resistance in the field is difficult because of the impact of the environment on disease development. The objective of this study was to evaluate SDS greenhouse screening methods and determine which best correlates with field resistance of soybean genotypes. Results from one greenhouse screening method and field SDS ratings were correlated suggesting that greenhouse screening can successfully predict the field SDS reactions of soybean genotypes. This information is useful to soybean pathologists and breeders interested in techniques to evaluate soybeans for resistance to this fungal disease.
Technical Abstract: Sudden death syndrome (SDS) caused by the soil borne fungus Fusarium solani f. sp. glycines (FSG) (syn. Fusarium virguliforme Akoi, O’Donnell, Homma and Lattanzi), is a major disease in soybean [Glycine max (L.) Merr.]. Selection for SDS resistance in the field is difficult because of the impact of the environment on disease development. The objective of this study was to evaluate two SDS greenhouse screening methods and determine which best correlates with field resistance of soybean genotypes. Three sets of genotypes were previously evaluated for field reaction to SDS and were placed into partially resistant, intermediate, and susceptible classes based on these field reactions. All three sets were evaluated for greenhouse SDS reactions with a cone inoculation method and two sets were evaluated with a tray inoculation method. For both greenhouse methods, the plants were inoculated with FSG infested white sorghum [Sorghum bicolor (L.) Moench] grain and foliar symptom severity (disease severity, DS) was rated 21 days after emergence. The cone method separated all three classes in one set, but failed to separate the intermediate and susceptible classes in two sets. The cone and field SDS ratings were significantly (P<0.05) correlated and these correlations ranged from 0.69 for Set 1 to 0.51 for Set 3. The correlations of SDS ratings for genotypes between field and greenhouse tray ratings was 0.54 (p<0.001) for Set 1 and 0.39ns for Set 2. Our results suggest that the cone method can successfully predict the field SDS reactions of genotypes.