Abstract
Plants produce a wide variety of triterpenes. Squalene, a linear triterpene synthesized via the cytosolic mevalonate pathway, is metabolized to steroids and triterpenoids. HMG-CoA reductase (HMGR), the key enzyme of the mevalonate pathway, is encoded by two genes, HMG1 and HMG2, in Arabidopsis. We have been isolated T-DNA insertion mutants for these genes and identified that triterpenes are involved in the cell elongation, the inhibition of senescence and the pollen development.
The gene expression profiles of wild-type plants treated with inhibitors of HMGR, squalene synthase, squalene epoxydase, C-14 reductase (FACKEL) and CYP90B1 (DWF4) were compared of that of hmg1 using a microarray technique. It was suggested that squalene is involved in the inhibition of senescence. The finding corresponded to the gene expression analyses in the various mutants downstream of hmg1 in the MVA pathway. We consider that squalene may play a role for the inhibition of senescence as an anti-oxidant compound.
