Methods and means are provided for reducing expression of a nucleic acid of interest, thereby altering the phenotype of an organism, particularly a plant, by providing aberrant, preferably unpolyadenylated, target specific RNA to the nucleus of the host cell. Preferably, the unpolyadenylated, target-specific RNA is provided by expresssion of a chimeric DNA construct comprising a promoter, a DNA region encoding the target specific RNA, a self-splicing ribozyme and a DNA region involved in 3' end formation and polyadenylation.
