The role of ZIP proteins in zinc assimilation and distribution in plants: current challenges

Abstract

Soils with mineral deficiencies lead to nutritional imbalance in crops worldwide. Zinc (Zn) is a micronutrient that is fundamental for plant growth and development, being essential for the proper functioning of a range of enzymes and transcription factors. Zn transporters tightly regulate Zn homeostasis. Plants contain a large number of Zn-responsive genes that are specifically expressed under Zn deficiency to ensure the coordination of assimilatory pathways and meet the physiological requirements. This review brings together a range of studies that have been undertaken to investigate the effects of Zn status on the regulatory mechanisms involved in plant mineral nutrition. The ZIP (ZRT, IRT-like Protein) family is especially implicated in Zn transport and in the maintenance of cellular Zn homeostasis. Regulation of expression in relation to plant tissue, mineral concentration, and species has been determined for several ZIP family members. In the omic era, genomic and proteomic approaches have facilitated a rapid increase in our understanding of the roles of ZIP family members and their regulation, though significant knowledge gaps remain. A comprehensive understanding of ZIP proteins could lead to many potential molecular applications to improve crop management and food quality.