Animal cell-death suppressors Bcl-xL and Ced-9 inhibit cell death in tobacco plants

In plants, events similar to programmed cell death have been reported [1] [2], although little is known of their mechanisms at the molecular level. To investigate the mechanism(s) involved, we overexpressed bcl-x(L), which encodes a mammalian suppressor of programmed cell death, in tobacco plants, under the control of a strong promoter [3]. In plants expressing Bcl-x(L), cell death induced by UV-B irradiation, paraquat treatment or the hypersensitive reaction (HR) to tobacco mosaic virus (TMV) infection was suppressed. The extent of suppression of cell death depended on the amount of Bcl-x(L) protein expressed. Similar enhanced resistance to cell death was found in transgenic tobacco plants overexpressing the ced-9 gene, a Caenorhabditis elegans homolog of bcl-x(L) [4], indicating that Bcl-x(L) and Ced-9 can function to inhibit cell death in plants.