This invention relates generally to methods for preparing plants, plant cells, or plant parts with increased content in one or more of protein, oil, or one or more amino acids. The invention also relates to transgenic plants comprising multiple genes of interest including a nucleic acid molecule encoding a polypeptide having pyruvate kinase activity and a nucleic acid molecule encoding a trehalose-6-phosphate synthase (TPS) homolog. Expression cassettes for achieving such gene expression manipulation, as well as recombinant constructs, vectors and plants, plant cells, or plant parts comprising the same, are also provided. Plants, plant cells, or plant parts with increased content in one or more of protein, oil, or one or more amino acids thus obtained may be useful in preparing foodstuffs and animal feeds and in plant breeding programs for developing further hybrid or inbred lines.