Genome-Wide Analysis of Vacuolar Iron Transporter (VIT) Gene Family in Phaseolus vulgaris L.: Functional Roles in Heavy Metal Stress

Vacuolar Iron Transporter (VIT) genes have been characterized and indicated to play critical roles in iron homeostasis in various plants. Heavy metals pose a significant challenge to bean cultivation, necessitating the development of heavy metal-resistant cultivars as a key strategy to mitigate their impacts. Vacuolar detoxification is a crucial strategy for plants to survive and adapt to the adverse environment caused by heavy metal stress. The current study used various bioinformatic tools to characterize the VIT gene in the bean, a significant member of the legume family and an important agricultural product, for the first time. The study identified and characterized 11 VIT genes (PhvulVIT-1–PhvulVIT-11) in the bean's genome. These genes displayed molecular weights (MW) ranging from 16.48 to 28.92 kDa and comprised 155–269 amino acid residues. The distribution of the 11 PhvulVIT genes on the four chromosomes was not homogeneous, and eight genes were observed to be located on chromosome 2. Gene duplication events suggested purifying selection as the primary evolutionary force, ensuring functional stability of duplicated genes. Phylogenetic analysis classified PhvulVIT genes into three clades, reflecting evolutionary relationships with orthologs in Arabidopsis thaliana and Glycine max. Cis-regulatory element analysis of promoter regions revealed key stress-responsive motifs like MYB, MYC, and ABRE, which are essential for plant responses to environmental stresses and phytohormone signaling. Additionally, the expression patterns of PhvulVIT under heavy metal conditions were examined using RNAseq. This study enhances our understanding of the functional roles of VIT genes in nutrient homeostasis and environmental stress adaptation, offering valuable insights for crop improvement strategies, including biofortification and the development of stress-tolerant cultivars.