Conversion of sugars to ethanol involves major energy losses. Rechanneling of the sugar utilization in-planta to oil biosynthesis instead of starch would have drastic positive effects on net carbon dioxide emission and energy output/input ratios in the utilization of biofuels, and would substantially increase the proportion of fossil fuels that can be replaced by bio-based fuels. This project aims at identifying the genetic switches in glucose utilization for starch synthesis and re-directing the reduced carbon to oil biosynthesis in cereals.
Oat kernels are used as a model system to identify the key genes involved in the switch from starch to oil synthesis in developing endosperm of cereals. Methods for liquid culturing of detached oat panicles from anthesis to seed maturity have been developed. This approach has enabled us to perform metabolic flux analysis by steady state isotopes in detached oat panicles from different oat varieties differing in oil content and to identify the key regulatory steps in oil accumulation. In conjunction with the metabolic flux analysis we are performing ‘Ultra’ EST (by pyrosequencing) on different parts of developing oat kernels from varieties with different oil content. Candidate genes regulating oil quantity in developing endosperm will be identified by comparing the transcript profiles of different varieties and tissues and finally by silencing the genes through antisense ODN inhibition approach in detached panicles. Identification of the genetic switch(es) of glucose utilisation between starch and glycolysis opens the venue to redirect the carbon flow to oil instead of starch by genetic engineering. Using oat as a model system for identification of regulatory switches would provide us with the enabling tools to transfer the knowledge to more important cereals like maize and wheat. In the long perspective one could envision that this knowledge would be also applied to plants accumulating large amount of starch or sugar in roots and/or to re-direction of cellulose to oil in wooden species.
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