Genetic engineering of plant cell walls for improved bioenergy production
|演題||Genetic engineering of plant cell walls for improved bioenergy production|
|講演者||Dr. Chandrashekhar P. Joshi （Department of Biological Sciences, Michigan Technological University）|
|場所||L12 lecture room|
Depleting fossil fuel reserves and growing demand for energy have necessitated the renewed search for alternative energy resources such as plants and algae. The first generation biofuels were produced from starch and sugars (bioethanol) and from seed oils (biodiesel). These, however, soon became negatively associated with issues such as competition with food supply, significant land-use changes and several other ethical issues. The production of second generation biofuels from lignocellulosic materials from grasses and trees requires high-input saccahrificationtechnologies involving extensive pre-treatments and expensive cellulolytic enzymes, adding to the high costs of second generation bioethanol. Recently, third generation biofuels derived from microalgae have attracted the attention of plant biologists and industrialists due to fast growth rate, high CO2 fixation ability and high production capacity of microalgae. Now, there also exists promising fourth generation of biofuels on the horizon which involves metabolically-engineering of plants and algae possessing traits such as high biomass yield, improved feedstock quality and high CO2 fixation. In recent years, efforts have been made via genetic engineering approaches for improving saccharification of cell walls. This presentation will focus on recent progress made in the alteration of cell wall properties through manipulation of native cell wall genes for enhanced saccharification and bioethanol production.Another use of plant biomass is for production of biodiesel. Recently, we enhanced accumulation of fatty acids (FAs) in stems of transgenic tobacco plants expressing Arabidopsis diacylglycerol acyltransferase 1 (DGAT1) and LEAFY COTYLEDON2 (LEC2) genes under a developing xylem-specific cellulose synthase promoter from aspen trees. The transgenic tobacco plants accumulated significantly higher amounts of FAs in their stems. On an average, DGAT1 and LEC2 overexpression showed a 63% and 80% increase in total FA production in mature stems of transgenic plants over that of controls, respectively. In LEC2 lines, the relative mRNA levels of the downstream genes encoding plastidic proteins involved in FA synthesis and accumulation were also elevated. Thus we provide a proof of concept for enhancing total energy yield per plant through accumulation of higher levels of FAs in transgenic stems for biodiesel production. The lignocellulosic material from stems can also be additionally used for bioethanol production.
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