QTL mapping of Fusarium head blight and Septoria tritici blotch in an elite hard red winter wheat population

Abstract

The objective of this study was to map loci associated with Fusarium head blight (FHB) traits and Septoria tritici blotch (STB) and plant height in a “Maxine/FTHP Redeemer” winter wheat population. Evaluation of FHB and STB resistance was performed using spray inoculation and under natural infections in replicated trials across three environments in Ontario, Canada. Selected lines of this population were tested for DON level in 2013 (FHB epidemic year) at three locations in Ontario. For both diseases, the population showed a continuous distribution pattern. DArT markers were used to generate a genetic map, and quantitative trait loci (QTL) analysis was performed by evaluating 105 doubled-haploid lines. The most effective QTL associated with FHB resistance were identified on chromosomes 2D, 4A, and 4B, coinciding with plant height QTL, being an indicative of the presence of the dwarf alleles on Rht-B1 and Rht8 loci in the present population. The 2D QTL is probably due to Rht8 + Ppd-D1, because of the association of the 2D QTL with both plant height and heading date. STB QTL were on chromosomes 2D, 4B, and 7A. The lines with the genotype 2D+ (Rht8), combined with 4A− and 4B+ (Rht-B1) QTL, showed the best genetic combination to obtain short and early maturing plants with good resistance to FHB, low DON, and adequate resistance to STB. Under natural FHB conditions, in the 2013 epidemic year, the presence of 2D+ allele reduced the DON accumulation when compared with lines with 2D− allele. Both diseases were screened in the same inoculated nursery, but did not influence each other. Knowledge of the best genetic combination will allow the successful improvement of elite wheat cultivars.