Arabidopsis 2010: Using Functional Genomics to Determine How and Why Plants Synthesize Diverse Triterpenoids

William Marsh Rice University, Houston TX

Investigators

Abstract

This multidisciplinary collaborative research is aimed at determining how and why plants synthesize diverse triterpenoids. This project will integrate reverse genetics in Arabidopsis, heterologous expression of cDNAs in yeast, spectroscopic and chromatographic structural determination, and gene expression analysis to elucidate the function of Arabidopsis triterpenoid biosynthetic genes and thereby triterpenoid biosynthetic pathways, control mechanisms, and biological function. Three of the characterized triterpenoid biosynthetic enzymes convert a shared substrate to different compounds; other enzymes to be studied may similarly provide structural diversity, metabolize different substrates, or provide means to spatially or temporally control expression and thus product formation. The effects of the mutations on plant growth, development, and triterpenoid composition will facilitate linking each triterpenoid biosynthetic gene with an enzyme of known catalytic activity and a specific biological role. Genes to be studied include apparent oxidosqualene cyclases, farnesyl pyrophosphate synthases, squalene synthases, squalene epoxidases, and cycloeucalenol isomerase. This work will provide a comprehensive accounting of triterpenoid skeletons synthesized by Arabidopsis, establish which compounds are derived from each gene product, and determine the spatial and temporal expression patterns of the various biosynthetic genes. These experiments will not only elucidate the biological importance of triterpenoid diversity, facilitating future modifications for agricultural benefit, but will provide students with broad interdisciplinary training that bridges modern chemistry and biology. The data from these studies will be publicly available on the project web site (http://www.bioc.rice.edu/~bartel/At_triterpenoids.html), and the knockout seeds will be deposited in the ABRC at Ohio State University for distribution to the community.