Genome-wide characterization of Ferritin gene family reveals BnaFER1.1 as a key regulator of salt stress tolerance in rapeseed (Brassica napus).

Abstract

Ferritins (FERs) are essential iron-storage proteins that maintain iron homeostasis, yet their contributions to growth and salt tolerance in Brassica napus remain poorly understood. In this study, a genome-wide analysis identified 9 BnaFER genes in the rapeseed genome. These genes were unevenly distributed across eight chromosomes and exhibited conserved gene structures and protein domains, indicating evolutionary conservation. Promoter analysis revealed numerous cis-acting elements associated with hormone, light, and stress responses. Expression profiling revealed that most BnaFER genes responded to salt stress, with both induction and repression patterns under NaCl treatment. BnaFER1.1, a chloroplast-localized member, was selected for functional characterization due to its strong stress responsiveness. Heterologous expression in Arabidopsis enhanced plant growth, increased silique length, silique number, and seed area and significantly improved salt tolerance. Physiological analyses revealed increased activities of catalase (CAT) and peroxidase (POD) and reduced accumulation of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA). Moreover, AtNHX1 and AtRD29A were significantly upregulated under salt stress in transgenic plants, indicating potential for improved ion homeostasis and osmotic adjustment. Collectively, BnaFER1.1 enhances salt tolerance through coordinated regulation of ROS detoxification and stress-responsive pathways. Our findings provide an important genetic foundation for the functional elucidation of BnaFER1.1 genes and a novel gene resource for improving salt tolerance in rapeseed.