Abstract: There are described plants of Papaver somniferum having reduced expression or activity of magnesium chelatase where-by the plants yield poppy straw having an altered alkaloid profile. In embodiments of the plants the reduced expression or activity of magnesium chelatase is associated with a trait for a lightened leaf colour. There are also described methods for producing the plants, and poppy straw, latex, concentrate of poppy straw and opium from the plants.

Abstract: There are provided plants of Papaver somniferum for the production of codeine, methods for providing the plants, and poppy straw, concentrate of poppy straw, latex, opium and codeine from the plants. The plants have codeine as the predominant alkaloid. Also disclosed are plants in which a stably inheritable high codeine chemotype trait is linked to a recessive trait for lighter leaf colour. Methods of producing such plants through the exposure of parent plant lines to mutagenizing agents are also disclosed.