Described herein are inventions in the field of genetic engineering of plants, including combinations of nucleic acid molecules encoding pyruvate kinase subunits to improve agronomic, horticultural, and quality traits. This invention relates generally to the combination of nucleic acid sequences encoding pyruvate kinase proteins that are related to the presence of seed storage compounds in plants. More specifically, the present invention relates to the use of these combinations of these sequences, their order and direction in the combination, and the regulatory elements used to control expression and transcript termination in these combinations in transgenic plants. In particular, the invention is directed to methods for manipulating seed storage compounds in plants and seeds. The invention further relates to methods of using these novel combinations of polypeptides to stimulate plant growth and/or root growth and/or to increase yield and/or composition of seed storage compounds.