Co-suppression of β-1,3-Glucanase Genes in Nicotiana tabacum

Abstract : Recent studies have demonstrated that introduction of sense gene constructs in plants can result in transgenic plants which express the transgene but also in plants with suppressed levels of transgene expression (reviewed by Jorgensen 1991; Kooter and Mol 1993; Matzke and Matzke 1993). In many silencing cases, the transgene and homologous host genes are coordinately suppressed in the plants, a phenomenon called co-suppression (Napoli et al. 1990). Although the underlying mechanism(s) are unknown, co-suppression has been reported in different plant species, and thus may represent a new approach to the manipulation of gene expression in plants. The finding that the presence of transgenes can influence the expression of resident genes via a homology-based mechanism opens up the possibility that this type of gene regulation may be naturally occurring in plants. A major challenge now is to unravel the molecular mechanism(s) responsible for transgene-induced gene silencing in plants.