Abstract: Disclosed herein are transgenic plants and plant cells having increased photosynthetic rate, increased biomass production, and/or improved cold tolerance compared to control plants (such as non-transgenic plants of the same species as the transgenic plants). In some examples, the transgenic plants/plant cells contain a plant transformation vector including a nucleic acid encoding a pyruvate orthophosphate dikinase (PPDK) polypeptide. Also disclosed herein are methods for making the transgenic plants, for instance by introducing into progenitor cells of the plant a plant transformation vector including a nucleic acid that encodes a PPDK polypeptide, and growing the transformed progenitor cells to produce a transgenic plant, in which the PPDK nucleic acid is expressed. Further disclosed herein are PPDK-encoding nucleic acids, PPDK polypeptides, and plant transformation vectors of use in producing the transgenic plants or plant cells.