Grant: Discovery Grants Program - Individual

Cuticular wax covers surfaces of land plants and serves as a protective barrier against water loss, UV-light, pathogens and insects. Major wax components are derived from saturated very long chain fatty acids (> C26 in length) via two wax biosynthetic pathways: an acyl reduction pathway and a decarbonylation pathway. Similar compositions of wax constituents comprising cuticular wax of Arabidopsis and other plant species suggest that these pathways are highly conserved in the plant kingdom. However, our knowledge of the wax biosynthetic enzymes, the nature of the biochemical reactions that they catalyze and their localization within the cell is limited. The long-term goal of my research program is to understand the biochemistry and molecular biology of wax biosynthesis and its regulation, and mechanism(s) involved in the transport of wax to the plant surface. We are using wax-deficient eceriferum (cer) mutants of Arabidopsis to identify and functionally characterize proteins involved in these processes. In this application, we propose to focus on CER19 and CER22 genes, because wax compositions of cer19 and cer22 mutants suggest that they encode proteins involved in the formation of hydrocarbons, the last fundamental part of wax biosynthesis that remains to be elucidated. In addition, our recent work on the cer7 mutant resulted in the discovery of the CER7 ribonuclease involved in regulation of cuticular wax biosynthesis. We plan to identify the mRNA targets of the CER7 enzyme and investigate their roles in the CER7-mediated control of wax production. The research proposed here will enhance our overall understanding of the wax biosynthetic machinery and result in the identification of genes essential for controlled genetic engineering of wax composition and accumulation to improve tolerance of crop plants to drought, and their resistance to pathogens and insects. Furthermore, the knowledge of the enzymology of hydrocarbon formation will lay the basis for the production of renewable high-efficiency biofuels that can replace fossil fuels which are currently escalating in price.