Abstract
In higher plants, various Z,E-mixed polyisoprenoids, including dolichol and polyprenol, are biosynthesized. However, physiological function of Z,E-mixed polyisoprenoids in higher plants is hardly elucidated. To understand the physiological roles of Z,E-mixed polyisoprenoids, we characterized Arabidopsis thaliana cis-prenyltransferases (AtCPTs) which catalyze the formation of the basic backbone of Z,E-mixed polyisoprenoids. Among AtCPTs analyzed so far, AtCPT5 showed a novel medium-chain CPT activity, catalyzing the formation of C30-35. In addition, AtCPT5 were induced in response to low temperature and hyper osmotic stress.
To reveal the roles of AtCPT5 in the stress responses, transgenic Arabidopsis lines with high expression of AtCPT5 driven by CaMV 35S promoter were prepared. Their root growths were repressed with increasing of the levels of AtCPT5 activity. Investigating the response to various abiotic stresses, such as low temperature, high salinity, high osmolality and abscisic acid treatment revealed the 35S:AtCPT5 transgenic lines acquired a tolerance to high osmolality.
