Researchers at the University of Tennessee have identified switchgrass genes that increase biomass yield and cellulose content in switchgrass and have potential to increase biomass yield and cellulose content in other monocot species such as corn, rice and barley. When the sequence of the derived amino acids were compared with other plant homolog genes, the cluster analysis showed that the genes were clustered into three groups, and each switchgrass gene is clustered with its homolog from other monocot species such as rice, maize, and barley, with a high percentage of amino acid identity (up to 98%). Transient expression analysis of the switchgrass gene for subcellular localization using a fluorescent protein marker showed that the protein was localized to the plant plasma membrane. Transgenic switchgrass plants overexpressing the switchgrass gene were produced and the plants looked phenotypically normal and showed an increase in the plant height, number of tillers, and dry biomass weight.
Dr. Mohnen's group at the University of Georgia has identified a clade of genes that are associated with the control of the biosynthesis of both pectin and lignin (and possibly xylan). Mutations of these genes in certain plants (including switchgrass and Populus) lead to considerable reduction of recalcitrance (v. wild type), as shown by means of bacterial degradation of modified biomass. Furthermore, Populus plants bearing some of these mutations have exhibited a considerable increase in height and stem diameter (v.wild type). Plants bearing these mutations may prove suitable for economically viable extraction and use of carbohydrates from plant cell wall, as recalcitrance is greatly reduced and rate of overall growth of modified plants increase.
UGA researchers developed a library of ~200 MAbs that recognize epitope structures characteristic of most major plant cell wall polysaccharides. These MAbs are monospecific with regard to the structure that they bind. They can provide temporal and spatial information about plant cell wall structures at the whole plant, tissue, cell, and sub-cellular levels and can be used to monitor and define changes in wall structure arising from developmental, environmental, and mutational influences. As importantly, MAbs can be used for qualitative and quantitative detection of carbohydrate epitopes in plant ex-tracts. In this document, we describe how MAbs can be used for characterization of biomass materials especially with regards to monitoring changes in cell wall structure that might impact biomass recalci-trance.
The researchers have created transgenic plants, which have a higher
biomass potential given increased plant size. The new plants also have a decreased resistance to enzymes, which in turn will decrease the cost of converting the plant into biofuel. The new framework allows for understanding cell wall synthesis better, and subsequently enables the creation of more transgenic plants
Biomass is a renewable resource that has shown promise to replace petroleum based fuels, while reduc-ing green house gas emissions. The plant cell walls, which are the dominant component of feedstocks, contain polysaccharides such as cellulose, heteroxylans, and glucomannans that can ultimately be con-verted to fuel. However, the production of biomass-based fuels has not been cost competitive relative to oil or other energy resources. A key challenge is cell walls have built up a natural protection (or recal-citrance) that makes the process of converting polysaccharides to fermentable sugars inefficient.
Overexpression of the foxtail milled (Setaria italica L.) pectin acetylesterase 1 (SiPAE1) gene in rice resulted in increased growth and biomass yirld and improved ethanol yirld from 18-56% in diverse over-expression lines compared to wild type and vector control lines.
The gene, an amino acid transporter, can used to (i) alter glucose and xylose release, (ii) alter syringyl to guaiacyl ratio in cell walls (iii) manipulate cellulose fiber extension, cell death, lignin content, and secondary cell wall formation, (iv) alter hexose and pentose sugar composition in the cell wall for biofuel production, (v) enhance resistance to pests and pathogens (vi) enhance plant growth, and the promoter associated with this gene can used for tissue specific gene expression.
This disclosure provides plants having desirable levels of lignin synthesis, sugar release, S/G ratio, and resistance to stress and pathogens; methods of selecting plants with such desirable levels of lignin synthesis, sugar release, S/G ratio, and resistance to stress and pathogens; methods of genetically modifying plants to modulate lignin synthesis, sugar release, S/G ratio, and resistance to stress and pathogens; and uses of such plants. The inventors have determined that the expression and/or activity of POPTR_0014s08530, a gene encoding an Angustifolia/CtBP transcription factor, modulates lignin synthesis, sugar release, S/G ratio, and resistance to stress and pathogens in plants. Plants with lignin synthesis, sugar release, S/G ratio, and resistance to stress and pathogens, based on modulation of the expression or activity of the POPTR_0014s08530 gene, have divergent uses including pulp and paper production, and ethanol/biofuel production.
The invention provides methods for transforming grass plants with Agrobacterium. The invention allows creation of transgenic grass plants without the need for callus as a target tissue for transformation, thus providing a rapid method for the production of transgenic grass plants. Transgenic grass plants produced by this method are also provided.
The invention provides coding and promoter sequences for a VS-1 and AP-2 gene, which affects the developmental process of senescence in plants. Vectors, transgenic plants, seeds, and host cells comprising heterologous VS-1 and AP-2 genes are also provided. Additionally provided are methods of altering nutrient allocation and composition in a plant using the VS-1 and AP-2 genes.
The invention provides methods for modifying lignin, cellulose, xylan, and hemicellulose content in plants, and for achieving ectopic lignification and, for instance, secondary cell wall synthesis in pith cells, by altered regulation of a WRKY transcription factor. Nucleic acid constructs for altered WRKY-TF expression are described. Transgenic plants are provided that comprise modified pith cell walls, and lignin, cellulose, and hemicellulose content. Plants described herein may be used, for example, as improved biofuel feedstock and as highly digestible forage crops.
The invention provides isolated fungal endophytes and synthetic combinations thereof with host grass plants. Methods for inoculating grass plant with the endophytes, for propagating the grass-endophyte combinations, and for producing feeds and biofuels from grass-endophyte combinations are also provided.
The invention provides methods for modifying lignin content and composition in plants and achieving associated benefits therefrom involving altered expression of newly discovered MYB4 transcription factors. Nucleic acid constructs for modifying MYB4 transcription factor expression are described. By over-expressing the identified MYB4 transcription factors, for example, an accompanying decrease in lignin content may be achieved. Plants are provided by the invention comprising such modifications, as are methods for their preparation and use.
The present invention relates to methods of blocking or reducing genetically modified plant (GMO) pollen flow using a “non-lethal” approach. In this aspect, at least one transgenic polynucleotide of interest is linked to a pollen-ablation construct as described herein. The pollen-ablation construct contains a polynucleotide encoding a restriction enzyme that renders the transgenic pollen unable to fertilize a sexually compatible ovule.
Researchers at the University of Tennessee’s Institute of Agriculture have isolated a novel promoter sequence from Populus that is highly, yet broadly inducible by high temperatures (40ºC), low temperatures (0ºC), drought, and flooding. This promoter sequence has been cloned, and when expressed in Arabidopsis, has been shown to induce reporter gene function in all tissue types tested (root, leaf, seed pot and flower). Experiments are currently underway to test this promoter sequence in several other economically important crops.
Researchers at the University of Tennessee have discovered a method to induce strong expression of any gene conferring resistance to pathogens, herbicides, salt, cold, drought, or insects by using two newly identified and recently characterized switchgrass promoters. These promoters stimulate constitutive expression with 2x and 4x greater activity than maize ubiquitin 1 (ZmUbi1) and CaMV 35S, respectively, driving gene expression in all tissues and organs of switchgrass. These novel components have the potential to be integrated into all monocot transformation systems, especially where multiple gene activation is needed. Interestingly, these promoters have a broad spectrum of taxonomic activity with additional expression capabilities in other monocots, dicots and ferns.
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