Transgene silencing / Ann Depicker, Matthew Sanders and Peter Meyer -- RNA interference : double-stranded RNAs and the processing machinery / Jan M. Kooter -- RNA-directed DNA methylation / Marjori Matzke [and others] -- Heterochromatin and the control of gene silencing in plants / G. Reuter, A. Fischer and I. Hofmann -- When alleles meet : paramutation / Marieke Louwers, Max Haring and Maike Stam -- Genomic imprinting in plants : a predominantly maternal affair / Ueli Grossniklaus -- Nucleolar dominance and rRNA gene dosage control : a paradigm for transcriptional regulation via an epigenetic on/off switch / Nuno Neves, Wanda Viegas and Craig S. Pikaard -- Virus-induced gene silencing / Tamas Dalmay -- MicroRNAs : micro-managing the plant genome / Sandra K. Floyd and John L. Bowman.