Fusarium head blight (FHB) is one of the most important and destructive wheat diseases worldwide, threatening both food security and safety. In this study, a recombinant inbred line (RIL) population with 269 F₆ lines developed from a cross between ‘Nanjing 8611’ and ‘Ocoroni’ was used to map quantitative trait loci (QTLs) for FHB resistance. Field FHB trials were conducted for three years in Nanjing, China, using point inoculation, and two years in Mexico with spray inoculation. A high-density genetic map was constructed for the RIL population using the wheat 55 K single nucleotide polymorphism (SNP) array. A total of 13 QTLs were detected on chromosomes 1B, 2D, 3B, 5D, 6D, and 7A, among which two major QTLs, QFhb.CIM-2D.1 and QDon.CIM-3B.1, were stably expressed in this study. Conditional QTL analysis suggested that QFhb.CIM-2D.1 contributes to reduced deoxynivalenol (DON) content via decreasing FHB severity, whereas QDon.CIM-3B.1 contributed to FHB resistance by directly controlling DON accumulation. Stacking of QFhb.CIM-2D.1 and QDon.CIM-3B.1 exhibited a marked increase in resistance against both FHB and DON. Furthermore, two Kompetitive Allele-Specific PCR (KASP) markers, KASP-1369 and KASP-8394, tightly linked to QFhb.CIM-2D.1 and QDon.CIM-3B.1, respectively, were developed and successfully validated in their respective genetic populations. Altogether, these results broaden the understanding of the genetic basis of resistance to FHB, and the developed markers are valuable for marker-assisted wheat breeding.

The emergence and spread of wheat blast caused by fungal pathogen Magnaporthe oryzae pathotype Triticum is a threat to global wheat production. The resistance level and genetic loci for blast resistance in Chinese germplasm remain unknown. A panel of 266 bread wheat accessions from China, CIMMYT-Mexico and other countries was screened for head blast resistance under 12 field experiments in Bolivia and Bangladesh. Subsequently, a genome-wide association study was performed to understand the genetic basis of wheat blast resistance. The average blast index of all the accessions was 53.7% ± 12.7%, and 10 accessions including Chinese accessions Yumai 10 and Yu 02321 showed moderate to high levels of blast resistance, accounting for only 3.8% in the panel. Fifty-eight significant SNPs clustered in a 28.9 Mb interval on the 2AS/2NS translocation region, explaining phenotypic variation between 10.0% and 35.0%. The frequency of the 2AS/2NS translocation in the Chinese accessions was as low as 4.5%. These results indicated that the 2NS fragment was the only major locus conferring resistance to wheat blast in this panel, and the resistant and moderately resistant lines identified could be deployed in breeding.

Tan spot (TS) and Septoria nodorum blotch (SNB), caused by Pyrenophora tritici-repentis and Parastagonospora nodorum, respectively, are important fungal leaf-spotting diseases of wheat that cause significant losses in grain yield. In this study, two recombinant inbred line populations, ‘Bartai’ × ‘Ciano T79’ (referred to as B × C) and ‘Cascabel’ × ‘Ciano T79’ (C × C) were tested for TS and SNB response in order to determine the genetic basis of seedling resistance. Genotyping was performed with the DArTseq genotyping-by-sequencing (GBS) platform. A chromosome region on 5AL conferred resistance to TS and SNB in both populations, but the effects were larger in B × C (R² = 11.2%–16.8%) than in C × C (R² = 2.5%–9.7%). Additionally, the chromosome region on 5BL (presumably Tsn1) was significant for both TS and SNB in B × C but not in C × C. Quantitative trait loci (QTL) with minor effects were identified on chromosomes 1B, 2A, 2B, 3A, 3B, 4D, 5A, 5B, 5D, 6B, and 6D. The two CIMMYT breeding lines ‘Bartai’ and ‘Cascabel’ contributed resistance alleles at both 5AL and 5BL QTL mentioned above. The QTL on 5AL showed linkage with the Vrn-A1 locus, whereas the vrn-A1 allele conferring lateness was associated with resistance to TS and SNB.