MYCATOXINS REVEAL CONNECTIONS BETWEEN PLANTS AND ANIMALS IN APOPTOSISAND CERAMIDE SIGNALING

Plants undergo programmed cell death during development and disease in contexts that are functionally analogous to apoptosis in animals. Rec ent studies involving plant cell death induced by mycotoxins, pathogen s and lethal mutations along with the cell-autonomous death during dev elopment now point to several conserved connections to apoptosis in an imals. Morphological markers indicative of apoptosis recently reported in plants include TUNEL positive cells, DNA ladders, Ca2+-activated n ucleosomal DNA cleavage, and formation of apoptotic-like bodies that o ccur in some but not all situations involving ordered cell death. In p arallel studies with animal and plant cells treated with sphinganine a nalog mycotoxins our results indicate that the induction and inhibitio n of death may be mediated by ceramide-linked signaling systems. The p resence and significance of ceramide-linked second messenger systems i s well documented in animals but is virtually unknown in plants. Furth er research will discern the manner in which the important function of programmed cell death is conserved as well as diverged between the tw o kingdoms.