The present invention provides a method of expressing a plant Lewis-type .beta.1,3-galactosyltransferase in an organism comprising the step of providing the organism with a nucleic acid molecule comprising a sequence A which is defined as being selected from: a) a sequence according to SEQ ID NO: 1 with an open reading frame from base pair 1-1932, j) a sequence which is at least 50% identical with SEQ ID NO: 1, k) a sequence which hybridizes with SEQ ID NO: 1 under stringent conditions, or l) a sequence which has degenerated to SEQ ID NO: 1 due to the genetic code, wherein the sequences a) to d) encode a plant protein having Lewis-type .beta.1,3-galactosyltransferase activity, or m) a sequence which is complementary to one of the sequences a) to d), and expressing a protein encoded by sequence A or if the organism comprises a sequence A in its wildtype form overexpressing a protein encoded by sequence A.