SGER: Molecular Cloning of a Gene required for Normal Isoprenoid Accumulation in Arabidopsis

Indiana University, Bloomington IN

Investigators

Abstract

The goal of this project is to gain a better understanding of the biosynthesis, compartmentation,and function of plant isoprenoids. Recent work in several laboratories has revealed the presence of two distinct isoprenoid biosynthetic pathways in plants: a mevalonate-dependent pathway that is responsible for the synthesis of sterols, brassinosteroids, cytokinins and other terpenoids, and a mevalonate-independent pathway that is involved in the production of plastidic isoprenoids (plastoquinones, phytyl tail of chlorophylls, carotenoids, etc.). However, much remains to be learned of the interactions between these different isoprenoid compartments in plant growth and development. To address this complex problem, this PI has identified mutants of Arabidopsis thaliana that are resistant to lovastatin (lvr ), a specific inhibitor of mevalonate synthesis that severely impairs root growth of wild type seedlings.One of these mutants, lvr 111, exhibits extreme resistance to lovastatin and is defective in chlorophyll and carotenoid pigmentation. Interestingly, F2 population analysis suggests that both phenotypes are caused by a single mutation. Since this mutant exhibits alterations in the cytoplasmic pathway (lovastatin resistance) as well as the plastidic pathway (pigmentation defect), the PI will test the hypothesis that the communication between these isoprenoid compartments is altered in the lvr 111 mutant. This will be accomplished by positional cloning and characterization of the LVR 111 gene, which will provide insights into the flux and/or function of isoprenoid compounds within plant cells.