Abstract
Cardiolipin (CL) is widely distributed in various prokaryotes and mitochondria of eukaryotes as a membrane phospholipid. We identified the Arabidopsis gene CLS encoding a CL synthase as the first gene from the multicellular organisms. We also isolated mutants in which the CLS gene is disrupted by T-DNA insertion and found some abnormalities in the cls/cls mutants. The abnormalities of cls-2/cls-2 plant were severer than those of cls-1/cls-1 plant. In vivo labelling experiments in which the seedlings were incubated with [33P] Pi for 17 hours revealed that the incorporation of radioactivity into CL in the total phospholipid labelling was higher in the cls-1/cls-1 than in the cls-2/cls-2, and that the extent of the CL labelling was correlated with the phenotypes. We also measured the labelling of CL in the mutants in which CLS expression can be induced by exogenously added estrogen. By the induction of CLS expression with estrogen, the extent of CL labelling in the mutant increased and concomitantly the growth of roots was recovered. These findings demonstrate that CLS can control the level of CL and the cls mutants are nice tools to investigate the physiological roles of CL.
