Mapping QTLs for Fusarium Head Blight Resistance in an Interspecific Wheat Population

Abstract

Fusarium head blight (scab) is one of the most widespread and damaging diseases of wheat, causing grain yield and quality losses and production of harmful mycotoxins. Development of resistant varieties is hampered by lack of effective resistance sources in the tetraploid wheat primary gene pool. Here we dissected the genetic basis of resistance in a new durum wheat (Triticum turgidum ssp. durum) Recombinant inbred lines (RILs) population obtained by crossing an hexaploid resistant line and a durum susceptible cultivar. A total of 135 RILs were used for constituting a genetic linkage map and mapping loci for head blight incidence, severity, and disease-related plant morphological traits (plant height, spike compactness, and awn length). The new genetic map accounted for 4,366 single nucleotide polymorphism markers assembled in 52 linkage groups covering a total length of 4,227.37 cM. Major quantitative trait loci (QTL) for scab incidence and severity were mapped on chromosomes 2AS, 3AL, and 2AS, 2BS, 4BL, respectively. Plant height loci were identified on 3A, 3B, and 4B, while major QTL for ear compactness were found on 4A, 5A, 5B, 6A, and 7A. In this work, resistance to Fusarium was transferred from hexaploid to durum wheat, and correlations between the disease and morphological traits were assessed.

Keywords: FHB resistance; QTL analysis; SNP markers; durum wheat; genetic map.

FIGURE 1

Spike morphology of FHB-susceptible durum wheat cv. Saragolla (a) and FHB-resistant hexaploid wheat line 02-5B-318 (b).

FIGURE 2

Diagrammatic representation of frequency distribution for FHB incidence and severity in the RIL population derived from crossing the resistant 02-5B-318 line and the susceptible cv. Saragolla in the three environments of Bologna 2012 (BO12) (A), Bologna 2013 (BO13) (B), and Bari 2013 (BA13) (C).

FIGURE 3

Schematic representation of durum wheat chromosomes reporting mapped QTL (LOD ≥ 3.0) for FHB incidence (red) and severity (blue), for plant height (green) and ear compactness (yellow). The analysis was conducted with Inclusive Interval Composite Mapping (ICIM) in the 135-RIL population derived from crossing the FHB-resistant 02-5B-318 line and the susceptible cv. Saragolla.