MicroRNA-Mediated Regulation of Cadmium Fate in Plants: Mechanisms and Translational Potential for Low-Cadmium Crop Development

Abstract

Cadmium (Cd) contamination threatens crop productivity and food safety through its accumulation in edible organs. This review synthesizes current knowledge of microRNA (miRNA)-mediated control of Cd fate along a continuous trajectory from root interception to edible-organ accumulation. We examine miRNA control of cell-wall remodeling and apoplastic Cd retention, followed by networks governing transporter activity, chelator supply, vacuolar sequestration, root-to-shoot transport, and reactive oxygen species homeostasis. We further evaluate major miRNA modules including miRNA397–LAC, miRNA156-related transport regulation for low-Cd crop improvement, and define how experimentally supported targets can guide molecular breeding through marker-assisted selection, genome editing, transgene-free manipulation, exogenous small RNA delivery, and emerging cross-kingdom sRNA regulation, together with their technical and ecological limitations. This framework provides practical guidance for prioritizing molecular targets, markers, and intervention strategies for developing low-Cd crops with reduced edible-organ accumulation and maintained stress resilience.