Abstract Iron (Fe), an essential micronutrient for plants, critically influences crop yield and quality. The IRON MAN ( IMA ) gene family regulates Fe uptake, but its functional role in apple ( Malus domestica ) remains unclear. This study performed phylogenetic and tissue-specific expression analyses of the MdIMAs gene family in apple under Fe deficiency. Among the MdIMAs genes, MdIMA1 was revealed to act as the key regulatory gene involved in Fe deficiency response. Heterologous expression of MdIMA1 in Arabidopsis thaliana significantly enhanced Fe deficiency tolerance, as manifested by increased fresh weight, chlorophyll content, ferric chelate reductase (FCR) activity, plasma membrane H + -ATPase activity, and Fe concentration. Moreover, genes associated with rhizosphere acidification and Fe transport and absorption were upregulated upon MdIMA1 overexpression, leading to promoted Fe uptake and utilization. Similarly, heterologous expression in tomato improved fresh weight and chlorophyll content, and enhanced both fruit yield and Fe concentration under Fe-deficient conditions. Meanwhile, MdIMA1 overexpression in apple calli resulted in elevated Fe deficiency tolerance through increasing H + -ATPase activity, while silencing MdIMA1 reduced this activity. Collectively, these results indicate that MdIMA1 positively regulates Fe uptake and utilization, providing a valuable target gene of significance for improving Fe nutrition in apples.
Li et al. (Sat,) studied this question.