*E-mail: Sundeep.Kumar@icar.gov.in

Fusarium Head Blight (FHB), caused predominantly by Fusarium graminearum and other Fusarium species, is a devastating fungal disease affecting wheat worldwide. It causes significant yield reductions, with severe outbreaks causing yield losses of up to 50% or more. Moreover, FHB-infected grains are often contaminated with mycotoxins, particularly trichothecenes such as deoxynivalenol (DON) and its derivatives. These mycotoxins not only reduce grain quality but also pose serious health risks to humans and livestock if consumed. This disease poses a significant threat to both durum wheat (Triticum turgidum L. subsp. durum) and bread wheat (Triticum aestivum L. subsp. aestivum), presenting a considerable challenge for wheat breeders worldwide.

Due to climate change, Fusarium head blight has become a serious threat to durum wheat in central India. Due to the complex nature of pathogen, it is very difficult to control the disease. Identification of resistance genes/QTLs for effective FHB resistance could greatly enhance our ability to breed durably resistant varieties. In spite of some notable achievements, the incorporation of resistance QTLs from non-adapted sources into commercial durum cultivars has faced challenges.

Factors such as the extended breeding process, linkage drag, or the suppression of resistance in durum backgrounds have hindered the release of commercial durum cultivars with these QTLs. Consequently, there is a growing preference for utilizing existing FHB resistance within durum cultivars as a more efficient strategy for quickly introducing durum wheat cultivars with improved resistance to the market. In view of the above, we performed a 90K SNP genotyping assay on an association panel of 285 diverse durum wheat genotypes including Indian wheat landraces.

These genotypes were evaluated for FHB resistance during 2020-21 and 2021-22 under controlled polyhouse conditions at IARI, New Delhi while, same set of lines were evaluated for FHB resistance under natural field conditions at IARI Regional Station, Wellington (Tamil Nadu) during 2021 and 2022.

Association analysis using three different multi-locus GWAS models (MLMM, FarmCPU and BLINK) identified a total of 17 significant SNPs which were identified on the threshold –log10 (H&B P-value) >0.05. These were mainly distributed on chromosomes 2A (3), 2B (2), 3A (1), 5B (3), 7A(1) and 7B (1) and some unknown markers were also identified. Four SNPs viz., wsnp_Ex_c16577_25095267, Kukri_rep_c115699_270, Ku_c7467_446 and Kukri_c9898_769 were consistently detected in most of the models and multiple environments.

Identified QTLs were further used for ontology analysis of the associated genomic regions to identify the potential candidate gene’s functions. Some highly favorable alleles were identified from the 4 different environment studied. Identified candidate genes and highly favourable alleles showed their role in FHB resistance directly or indirectly.

The information generated in this study will be of potential value for improving FHB resistance in wheat cultivars using marker-assisted selection.