XVI International Botanical Congess
In the mevalonate (MVA)-dependent, cytoplasmic isoprenoid pathway the intermediate farnesyl-PP (FPP) serves as substrate for sterol biosynthesis, for protein farnesylation, etc. Growth inhibition of tobacco BY-2 (TBY-2) cells by mevinolin, an inhibitor of hydroxymethylglutaryl-CoA reductase (HMGR), regulating MVA synthesis, could only partially be overcome by exogenous farnesol. We thus examined the effect of farnesol alone on TBY-2 cells. Highly diluted cells were sensitive, with 25 µM farnesol needed to induce 100% cell death. Less diluted cells were less sensitive. Mevinolin stimulated HMGR gene expression and activity, but also did, synergistically, farnesol. It seems plausible that overstimulation of HMGR activity might lead to induction of apoptosis. Our studies demonstrate similarities to the situation in mammalian cell systems, but also fundamental differences.