Inheritance of septoria glume blotch resistance in wheat
Abstract
Septoria glume blotch, caused by Stagonospora nodorum, is a major wheat disease throughout the world. The purpose of this study is to determine (1) the influence of inoculum concentration, moist period duration, and temperature on S. nodorum development, (2) the inheritance of Septoria glume blotch resistance in wheat, and (3) the chromosome location of Septoria glume blotch resistance genes. In Experiment One, the effects of three inoculum concentrations, four moist period durations, and two temperatures were determined on Septoria glume blotch development on wheat. Adult plants were inoculated in the greenhouse and the percentage of diseased tissue was estimated on the flag leaves and spikes several times over a 22-day period. As each variable was increased or lengthened, disease severity, measured by area under disease progress curves (AUDPC), generally increased significantly. Of the four cultivars tested, disease development was least severe on 'Coker 84-27.' Additionally, temperature sensitive gene(s) may have been detected in the cultivar Auburn. In Experiment Two, crosses were made between 'Cotipora' and the susceptible Purdue line, P831791A1-1-6. Populations of parents, F$\sb1$, F$\sb2$, BCF$\sb1$, and BCF$\sb2$ were inoculated in the greenhouse and the percentage of diseased tissue was estimated four times over a 20-day period. Correlations between AUDPCs of spikes and flag leaves were low, indicating resistance is at least partially controlled by different genes in these two plant organs. Resistance was partially dominant in the F$\sb1$ generation. In F$\sb2$, BCF$\sb1$, and BCF$\sb2$ generations, however, dominant gene action for spike and flag leaf resistance was not evident. The gene number estimate for spike resistance was 3.16. Broad sense heritability estimates were 0.51 and 0.34 for reaction of spikes and flag leaves, respectively, to S. nodorum. In Experiment Three, Cotipora was used to pollinate 21 monosomic lines of the hard red winter wheat cultivar 'Wichita.' F$\sb2$ monosomic families and parents were inoculated in the greenhouse and 14-day AUDPCs were calculated for the flag leaf reaction, whereas 14-day and 17-day AUDPCs were calculated for the spike reaction. At P = 0.01, monosomic families 3A and 4A were resistant for the flag leaf reaction, and monosomic families 3A, 4A, 7A, and 3B were resistant for the spike reaction.
Degree
Ph.D.
Advisors
Ohm, Purdue University.
Subject Area
Agronomy|Plant pathology
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