A Novel Quantitative Trait Locus on Chromosome 7D Derived from <i>Aegilops tauschii</i> Confers Moderate Field Resistance to Wheat Blast

Wheat blast is a devastating disease in the tropical and subtropical regions of South America and has recently spread to Bangladesh and Zambia. Host resistance to this disease has primarily relied on the 2NS/2AS translocation, making it crucial to identify and utilize novel sources of resistance. In the current study, a recombinant inbred line population consisting of 345 BC₁F₄ progenies was generated, using the susceptible wheat genotype 'Gladius' as the female and recurrent parent and the resistant <i>Aegilops tauschii</i> line 'KU-2097' as the male parent. Field phenotyping was conducted at two locations in Bolivia and one in Bangladesh, each with two sowing dates, during the 2022/2023 or 2023 cropping cycles. Genotyping was performed using DArTseq technology. Quantitative trait locus (QTL) mapping identified a major and consistent QTL on the long arm of chromosome 7D, designated as <i>Qwb.cim-7D</i>, which explained 7.7 to 50.6% of the phenotypic variation across different experiments. The DArTseq markers in the QTL region were converted to KASP markers, enabling the precise mapping of this QTL to a genomic region between 619.90 and 625.61 Mb, flanked by the KASP markers <i>K3222157</i> and <i>K1061589</i>. This novel QTL, along with its flanking markers, could be valuable for breeding programs targeting wheat blast resistance.