Deficiency in fatty acid synthase leads to premature cell death and dramatic alterations in plant morphology

An Arabidopsis mosaic deafh1 (mod1) mutant, which has premature cell death in multiple organs, was isolated, mod1 plants display multiple morphologica l phenotypes, including chlorotic and curly leaves, distorted siliques, pre mature senescence of primary inflorescences, reduced fertility, and semidwa rfism. The phenotype of the mod1 mutant results from a single nuclear reces sive mutation, and the MODI gene was isolated by using a map-based cloning approach. The MOD1 gene encodes an enoyl-acyl carrier protein (ACP) reducta se, which is a subunit of the fatty acid synthase complex that catalyzes de novo synthesis of fatty acids. An amino acid substitution in the enoyl-ACP reductase of the mod1 mutant causes a marked decrease in its enzymatic act ivity, impairing fatty acid biosynthesis and decreasing the amount of total lipids in mod1 plants, These results demonstrate that a deficiency in fatt y acid biosynthesis has pleiotropic effects on plant growth and development and causes premature cell death.