Latent function of microorganisms on plant iron acquisition

Iron deficiency in plants is a worldwide agricultural problem. It has been proved that soil microorganisms have a beneficial effect on the iron acquisition of some plants, but the underlying mechanism is still unclear. Based on last ten years' research results, possible mechanism on how the microorganisms favor plant iron acquisition was discussed in this review. Iron-deficiency-induced root exudates, such as phenolic and flavin compounds, acting as inhibitors and carbon sources, affected the architecture of microorganisms in the rhizosphere and induced a formation of a specified microorganism community. Those specified microorganisms in turn benefited the plant iron acquisition through the secretion of siderophore which could improve the bioavailability of iron in soil. In addition, the symbiosis between some microorganisms and plants could also improve plant iron nutrient status. The underlying processes may involve: the formation of rhizobium nodulation enhanced plant iron-deficient response, and mycorrhizal fungi infected root which improved the iron nutrient status through enlarging absorption area and excreting the materials which chelated iron of plant.