Genetic basis and multi-environment GGE-biplot evaluation of common bunt resistance in Turkish bread wheat landraces

Abstract Türkiye, one of the primary centers of wheat domestication, harbors a rich landrace diversity adapted to diverse agro-ecological zones. Common bunt ( Tilletia foetida ) is a seed-borne disease that causes substantial yield and quality losses. In this study, the reactions of 80 local bread wheat genotypes collected from five Turkish provinces to common bunt were evaluated over two cropping seasons (2023–2024 and 2024–2025) under artificial epidemic conditions in Kırşehir and Ankara. Genotype main effects and genotype × environment interactions were analyzed using the GGE-biplot approach. Molecular screening with bunt-resistance-associated markers was performed to detect the presence of the Bt8 , Bt9 , Bt10 , and Bt11 resistance genes. Phenotypic assessments showed that 56% of the genotypes were resistant. The Bt10 gene was identified in 13 genotypes, Bt8 in 9 genotypes, Bt11 in 2 genotypes, and a combined Bt8 + Bt10 gene set in 2 genotypes, whereas Bt9 was not detected in any genotype. The GGE-biplot explained 98.6% of the total variation and highlighted genotypes 67, 68, and 72 as superior under Ankara conditions and genotype 73 under Kırşehir conditions. Phenotypic resistance consistent with the presence of Bt8 , Bt10 , and Bt11 provides a valuable genetic resource for breeding bunt-resistant wheat lines. Marker-assisted selection, particularly pyramiding Bt8 and Bt1 0, is recommended to accelerate the development of durable resistance.