Compositions and methods for improving plant growth are provided herein. Polynucleotides encoding photosystem I reaction center subunit N (PSAN) proteins, polypeptides encompassing PSAN 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.