Production of proteases in plants is set forth, whereby heterologous DNA encoding the protease is introduced into the plant and expression of the protein achieved. By such methods, expression is achieved in plants wherein the plant cell is not damaged, the protein can be recovered without contamination by other proteases, and can be expressed at levels such that commercial production of the enzyme is obtained. Expression levels can be at 0.1% of total soluble protein of the plant, or higher.