The subject invention relates to plants and the starch produced by plants. In particular, the invention relates to processes for the modification of a plant so that the starch produced by the plant comprises amylopectin of an altered structure and/or the starch has an altered gelatinization temperature. The processes principally comprise engineering gene involved in amylopectin synthesis. In a preferred embodiment the starch synthase IIa gene is modified. Also disclosed are processes for altering genes to provide plant which produce starch having a desired gelatinization temperature, and methods of identifying the changes that can be made in genes to achieve a desired gelatinization temperature in the starch produced by a plant comprising such genes. Further disclosed are modified plants and the starch products of the plants.