LEFPS1, a tomato farnesyl pyrophosphate gene highly expressed during earlyfruit development

Farnesyl pyrophosphate synthase (FPS) catalyzes the synthesis of farnesyl p yrophosphate, a key intermediate in sterol and sesquiterpene biosynthesis. Using a polymerase chain reaction-based approach, we have characterized LeF PS1, a tomato (Lycoperscion esculentum cv Wva 106) fruit cDNA, which encode s a functional FPS. We demonstrate that tomato FPSs are encoded by a small multigenic family with genes located on chromosomes 10 and 12. Consistent w ith farnesyl pyrophosphate requirement in sterol biosynthesis, FPS genes ar e ubiquitously expressed in tomato plants. Using an LeFPS1 specific probe, we show that the corresponding gene can account for most of FPS mRNA in mos t plant organs, but not during young seedling development, indicating a dif ferential regulation of FPS genes in tomato. FPS gene expression is also un der strict developmental control: FPS mRNA was mainly abundant in young org ans and decreased as organs matured with the exception of fruits that prese nted a biphasic accumulation pattern. In this latter case in situ hybridiza tion studies have shown that FPS mRNA is similarly abundant in all tissues of young fruit. Taken together our results suggest that several FPS isoform s are involved in tomato farnesyl pyrophosphate metabolism and that FPS gen es are mostly expressed in relation to cell division and enlargement.