Iron biofortification and increased resistance level to leaf rust of spring wheat lines by mutation of vacuolar iron transporters, VIT.

Leaf rust (LR), caused by the obligate biotrophic fungus Puccinia triticina Eriks., is a major disease threatening wheat productivity and grain nutritional quality worldwide. This study evaluated advanced M₄ mutant lines of spring wheat generated by gamma irradiation (250-350 Gy) of cv. Kazakhstanskaya-10 to investigate the relationship between LR resistance and vacuolar iron (Fe) transport. Phenotypic and semi-quantitative histological analyses identified highly resistant mutant lines exhibiting both seedling and adult-plant resistance. Resistant genotypes displayed an early pre-haustorial hypersensitive response that was absent in the susceptible wild-type. Gene-targeted sequence analysis of the TaVIT4-D vacuolar iron transporter locus (XM_044518495.1) revealed a polymorphism-rich region characterized by an elevated frequency of transition and transversion events. Transmembrane topology prediction and hydropathy analyses indicated that several non-synonymous, charge-altering amino-acid substitutions were localized within predicted cytosolic Fe-binding regions between TMH2 and TMH3, altering local physicochemical properties while preserving the overall transmembrane architecture. These mutations were associated with increased grain Fe accumulation, with the most resistant mutant line exhibiting a 2.11-fold increase in grain Fe concentration relative to the wild-type. Collectively, the findings support a potential role of TaVIT4-D variation in coordinating LR resistance and grain Fe accumulation and are consistent with a model involving Fe-withholding nutritional immunity and oxidative defense. The results suggest that induced mutagenesis affectingTaVIT4-D may represent a promising non-transgenic strategy for improving both disease resistance and grain micronutrient content in wheat.

Supplementary information: The online version contains supplementary material available at https://doi.org/10.1007/s12298-026-01812-5.