title: Viroid pathogenicity: one process, many faces.
abstract: Despite the non-coding nature of their small RNA genomes, the visible symptoms of viroid infection resemble those associated with many plant virus diseases. Recent evidence indicates that viroid-derived small RNAs acting through host RNA silencing pathways play a key role in viroid pathogenicity. Host responses to viroid infection are complex, involving signaling cascades containing host-encoded protein kinases and crosstalk between hormonal and defense-signaling pathways. Studies of viroid-host interaction in the context of entire biochemical or developmental pathways are just beginning, and many working hypotheses have yet to be critically tested.
authors: Molecular Plant Pathology Laboratory, USDA/ARS, Beltsville, MD 20705, USA; E-mail:  rose.hammond@ars.usda.gov.
authors: Robert A
authors: RA
authors: Owens
authors: Rosemarie W
authors: RW
authors: Hammond