Stagonospora nodorum blotch (SNB) is an important fungal disease of wheat in Western Australia. Many resistance donors are in poor quality backgrounds. It is crucial to continue search for additional genes for effective improvement of resistance.
This research focussed on different resistant sources in five doubled haploid mapping populations: IGW2471/Wyalkatchem (I/W), AGT Young/Aus33414 (Y/A), BT Schomburgk/AUS33384 (S/A), Machete/Magenta (M/M) and CPI33842/Janz (C/J). Each population was assessed at least twice during 2012 to 2015.
Trials were conducted in the field and/or controlled environment using a randomised block design with three replications. Inoculation was done using a mixture of SNB isolates and the same inoculum mixture was used in repeated trials. Plants were assessed for percentage leaf area diseased at seedling and at head emergence. Field trials for I/W were conducted in a split-plot design of infected and fungicide protected main plots and were also assessed for relative grain weight (RGW). Populations showed continuous distribution and transgressive segregation for various traits. Correlations between assessments made at the same growth stage in different years were moderate to high (r = 0.4 to 0.8). Correlations between assessments made at seedling and adult stages within the same trial were low to moderate (r = 0.1 to 0.7) indicating independent inheritance of resistance at the two growth stages.
Loci for SNB leaf resistance at the adult plant stage were detected on chromosomes 2B, 2D, 3B, 4B, 5A and 6B in I/W; on 2B, 4D, 6A and 7D in Y/A; on 1B, 2D and 6B in S/A; on 3B in M/M and on 1B in C/J. Loci for SNB seedling resistance were detected on 2B in I/W; on 5D in Y/A; on 5B in M/M and on 3B in C/J. Loci for SNB resistance measured as RGW were detected on 2B, 3A, 5B and 7B in I/W.