The signalling molecule 1-(3,5-dichloro-2,6-dihydroxy-4-methoxyphenyl) hexan-1-one (DIF-1) is required for differentiation and pattern formation in Dictyostelium discoideum development. DIF-1 is synthesized by three enzymes, a hybrid polyketide synthase, a flavin-dependent halogenase, and a des-methyl-DIF-1 methyltransferase. The genome data on the related species D. purpureum are now public. Using this genome information, des-methyl-DIF-1 methyltransferase of D. purpureum was identified, and was named Dp dmtA. Overexpression of Dp dmtA complemented the defects in basal disc formation and lower cup formation in a dmtA knock-out mutant of D. discoideum. This indicates that Dp dmtA has the same function as D. discoideum dmtA and compensates for loss of the dmtA gene in the D. discoideum dmtA mutant. The materials released in the medium by D. purpureum contained stalk-inducing activity with the same retention time as that of DIF-1 in HPLC fractionation. This indicates that the stalk-inducing signal of DIF-1 and des-methyl-DIF-1 methyltransferase are conserved in D. purpureum.