A gene stacking approach leads to engineered plants with highly increased galactan levels in Arabidopsis [electronic resource]

• Ngôn ngữ: eng
• Ký hiệu phân loại: 621.48 Nuclear engineering
• Thông tin xuất bản: Washington, D.C. : Oak Ridge, Tenn. : United States. Dept. of Energy. Office of Science ; Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2014
• Mô tả vật lý: Size: Article No. 344 : , digital, PDF file.
• Bộ sưu tập: Metadata
• ID: 263764
• Chủ đề: 1. 09 biomass fuels; 2. 60 applied life sciences; 3. Galactan; 4. Plant cell wall; 5. Udp-glucose 4-epimerase

Tóm tắt

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 Background:<
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  Engineering of plants with a composition of lignocellulosic biomass that is more suitable for downstream processing is of high interest for next-generation biofuel production. Lignocellulosic biomass contains a high proportion of pentose residues, which are more difficult to convert into fuels than hexoses. Therefore, increasing the hexose/pentose ratio in biomass is one approach for biomass improvement. A genetic engineering approach was used to investigate whether the amount of pectic galactan can be specifically increased in cell walls of Arabidopsis fiber cells, which in turn could provide a potential source of readily fermentable galactose. <
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 Results:<
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  First it was tested if overexpression of various plant UDP-glucose 4-epimerases (UGEs) could increase the availability of UDP-galactose and thereby increase the biosynthesis of galactan. Constitutive and tissue-specific expression of a poplar UGE and three Arabidopsis UGEs in Arabidopsis plants could not significantly increase the amount of cell wall bound galactose. We then investigated co-overexpression of <
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 UGE2 together with the ?-1,4-galactan synthase GalS1. Co-overexpression of <
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 UGE2 and GalS1 led to over 80% increase in cell wall galactose levels in Arabidopsis stems, providing evidence that these proteins work synergistically. Furthermore, <
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 UGE2 and GalS1 overexpression in combination with overexpression of the NST1 master regulator for secondary cell wall biosynthesis resulted in increased thickness of fiber cell walls in addition to the high cell wall galactose levels. Immunofluorescence microscopy confirmed that the increased galactose was present as ?-1,4-galactan in secondary cell walls. <
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 Conclusions:<
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  This approach clearly indicates that simultaneous overexpression of <
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 At<
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 UGE2 and GalS1 increases the cell wall galactose to much higher levels than can be achieved by overexpressing either one of these proteins alone. Moreover, the increased galactan content in fiber cells while improving the biomass composition had no impact on plant growth and development and hence on the overall biomass amount. Thus, we could show that the gene stacking approach described here is a promising method to engineer advanced feedstocks for biofuel production.