Compositions and methods for improving plant growth are provided herein. The maize RbcS7A promoter is provided which is a developmentally regulated promoter. Polynucleotides encoding ferredoxin-thioredoxin reductase proteins, polypeptides encompassing ferredoxin-thioredoxin reductase proteins, and expression constructs for expressing genes of interest whose expression may improve agronomic properties including but not limited to crop yield, biotic and abiotic stress tolerance, and early vigor, plants comprising the polynucleotides, polypeptides, and expression constructs, and methods of producing transgenic plants are also provided.