Plant responses to iron deficiency and toxicity and iron use efficiency in plants

Abstract

Iron (Fe) is the fourth most abundant mineral in the Earth's crust essential for plant growth. However, if overloaded, Fe becomes toxic for plants as a highly reactive Fenton catalyst. Higher plants have developed two distinct adaptive strategies to cope with low Fe availability in soils, such as the reduction-based strategy (Strategy 1) in nongraminaceous plants, and the chelation-based strategy (Strategy 2) in graminaceous species. The ability of plants to improve Fe availability in the rhizosphere and its internal use efficiency will strongly affect both crop yield and quality in terms of Fe source for humans. Understanding the mechanisms involved in Fe uptake, transport, and storage is essential for breeding crops more tolerant to Fe-limited conditions. This review summarizes the current knowledge of root acquisition of Fe (deficiency), binding and detoxification of Fe (toxicity), long-distance root-to-shoot transport including loading of Fe into edible tissues, and molecular regulation of Fe use efficiency.