Abstract: Certain embodiments of the invention provide methods of selecting a mutant plant cell that overproduces a compound that activates an estrogen receptor (ER) beta but does not activate an ER alpha.

Abstract: Certain embodiments of the invention provide a method comprising: a) transforming cells from a selected plant with a vector comprising a gene encoding a heterologous target protein, to obtain transgenic primary plant cells, wherein the selected plant is from a species that produces activators or inhibitors of the heterologous target protein; b) mutagenizing an explant obtained from the transgenic primary plant cells to form mutagenized transgenic cells; and c) exposing the mutagenized transgenic cells to a compound, wherein mutagenized transgenic cells that overproduce one or more activators or inhibitors of the heterologous target protein, as compared to a non-mutant transgenic plant cell from the same species, survive; and wherein mutagenized transgenic cells that do not overproduce one or more activators or inhibitors of the heterologous target protein, as compared to a non-mutant transgenic plant cell from the same species, die.