Commercial production of the allergen Amb a1 by transient expression in plants

The present invention relates to a plant cell comprising a DNA molecule comprising at least one heterologous nucleotide sequence encoding a prepro a pectate lyase selected from Amb a 1, the alpha subunit of Amb a 1, the sub -unity beta Amb a 1, and homologous Amb a 1, operably linked to a strong promoter.