Identification and validation of a major QTL on chromosome 2A for wheat-Parastagonospora nodorum interactions

Wheat (Triticum aestivum L.) is frequently affected by Septoria nodorum blotch (SNB), a fungal disease that significantly reduces wheat yields. In this study, two recombinant inbred line (RIL) populations, developed from crosses involving two elite CIMMYT breeding lines (WUYA and KATH) and a common susceptible male parent (CIANO T79), were used to detect quantitative trait loci (QTL) associated with SNB resistance. High-density genetic maps were constructed for these RIL populations by incorporating presence/absence variation (PAV) markers using the DArTseq genotyping platform. Three major and stable QTL linked to SNB resistance were identified on chromosomes 2A, 4B, and 5B. Among these, QSnb.cim-2A accounted for 22.16%-28.74% and 17.62%-19.71% of the phenotypic variation in the WUYA/CIANO T79 and KATH/CIANO T79 populations, respectively, and it was also validated in the CASCABEL/CIANO T79 RIL population. The remaining two QTL, QSnb.cim-4B and QSnb.cim-5B, were found to be associated with Rht-B1b and tsn1, respectively. The combined effect of these three QTL significantly improved SNB resistance while also reducing plant height, indicating their promising utilization in wheat breeding programs.

The online version contains supplementary material available at 10.1186/s42483-025-00371-z.