Abstract
Z,E-mixed polyisoprenoids, dolichols and polyprenols, are synthesized ubiquitously in all organisms. In eukaryotes, dolichols (C70-120) play an indispensable role as glycosyl carrier lipids in the biosynthesis of glycoproteins on endoplasmic reticulum. In addition, higher plants have other type of Z,E-mixed polyisoprenoid so called ficaprenols (C50-60), in plastids. However, no physiological significance of ficaprenols in plastids has been elucidated. AtCPT4, an Arabidopsis cis-prenyltransferase, was shown to be localized to chloroplast and catalyze the formation of the backbone of C50 ficaprenols. In this meeting, we report physiological functions of AtCPT4.
AtCPT4 showed a light cycle-dependent expression under long-day condition. The AtCPT4 mutant showed increased elongations of petioles and hypocotyls under long-day condition, while no significant alteration in the continuous dark. Elongation of petioles in atcpt4 was suppressed by the addition of an auxin transport inhibitor. Moreover, IAA6 was up-regulated in atcpt4. These results suggest that AtCPT4 responsible for the biosynthesis of ficaprenols in plastids functions in a photo-responsive growth regulation in Arabidopsis.
