When bigger is better: the role of polyploidy in organogenesis

•The large cells that are necessary in plant and animal organs usually are generated by increased ploidy.•A large cell has multiple advantages versus a comparable mass of diploid cells.•Cell hypertrophy via increased ploidy can produce an envelope or control organ shape.•Polyploidy is linked to cell differentiation and function.

Defining how organ size is regulated, a process controlled not only by the number of cells but also by the size of the cells, is a frontier in developmental biology. Large cells are produced by increasing DNA content or ploidy, a developmental strategy employed throughout the plant and animal kingdoms. The widespread use of polyploidy during cell differentiation makes it important to define how this hypertrophy contributes to organogenesis. I discuss here examples from a variety of animals and plants in which polyploidy controls organ size, the size and function of specific tissues within an organ, or the differentiated properties of cells. In addition, I highlight how polyploidy functions in wound healing and tissue regeneration.