Abstract
Transcription factors regulating crop uptake and translocation of the micronutrient Cu have not been identified. We isolated a novel R2R3-MYB transcription factor, OsMYB84, and showed that it was a positive regulator involved in uptake and transport of Cu via activation of OsCOPT2 and OsHMA expression. OsMYB84 was highly expressed in roots and anthers and induced by Cu. Overexpression of OsMYB84 promoted uptake and root-to-shoot translocation of Cu in rice, facilitated Cu distribution into grain and increased grain yield. In contrast, mutation of OsMYB84 reduced Cu concentration in xylem sap. OsMYB84 bound to the promoter region of OsCOPT2 and OsHMA5 and upregulated their expression. OsCOPT2 mutants showed reduced uptake of Cu and OsHMA5 overexpression lines showed increased root-to-shoot translocation of Cu.
