OsHIPP24 is a Copper Metallochaperone Which Affects Rice Growth

Copper (Cu) is a trace mineral nutrient essential for plant growth; consequently, its uptake, trafficking, and redistribution are precisely controlled. Currently, little is known about the underlying regulatory mechanisms in rice. In this work, we identified OsHIPP24 as a Cu metallochaperone in rice. Heterologous expression of OsHIPP24 in wild-type yeast (Saccharomyces cerevisiae) strain BY4741 increased accumulation of Cu, as well as cadmium (Cd). OsHIPP24 was expressed constitutively in most tissues of rice, including root, stem, leaf, leaf sheath, internode, rachis, and spikelet, and particularly high in root stele along with the vascular bundle of the shoot. Overexpression or knockout of OsHIPP24 in rice led to stunted growth and reduced plant height, regardless of Cu levels in the growth medium. Taken together, these observations indicated that the physiological roles of OsHIPP24 involve the delivery of metal micronutrients via vascular tissues, and that OsHIPP24 plays a crucial role in the growth of rice.