A process for the preparation of an adventive embryo of a plant belonging to the genus Podophyllum, comprising the steps of preparing cells of a plant belonging to the genus Podophyllum, incubating the cells in a sugar free medium or a medium containing up to 2% by weight sugar, and then incubating the cells in a medium containing more than 2% by weight of sugar to generate an adventive embryo; a process for the production of a podophyllotoxin compound comprising the steps of preparing an adventive embryo of a plant belonging to the genus Podophyllum, culturing the adventive embryo to generate an adventitious organ, culturing the adventitious organ to produce a podophyllotoxin compound, and recovering the podophyllotoxin compound; and a process for the production of a podophyllotoxin compound, comprising the steps of preparing de-differentiated cells or tissue of a plant belonging to the genus Podophyllum culturing the de-differentiated cells or tissue in a liquid medium to generate a differentiated organ, culturing the differentiated organ on a solid medium to produce a podophyllotoxin compound, and recovering the podophyllotoxin compound.