A plant gene, Esr1, has been found which when overexpressed in plant cells results in cells which have cytokinin-independent cell growth. This feature allows the encoded protein ESR1 to be used as a selectable marker of transformed cells by growing the transformed cells on cytokinin-free media. It has also been found that overexpression of ESR1 in cells grown in the presence of cytokinins results in a higher regeneration of plants. This feature allows the gene to be used to obtain greater regeneration of plant cells.