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The Tceg1 Beetle (Tribolium Castaneum) Cellulase Produced In Transgenic Switchgrass Is Active At Alkaline Ph And Auto-Hydrolyzes Biomass For Increased Cellobiose Release, Jonathan D. Willis, Joshua N. Grant, Mitra Mazarei, Lindsey M. Kline, Caroline S. Rempe, A. Grace Collins, Geoffrey B. Turner, Stephen R. Decker, Robert W. Sykes, Mark F. Davis, Nicole Labbe, Juan L. Jurat-Fuentes, C. Neal Stewart Jr

Plant Sciences Publications and Other Works

Background

Genetically engineered biofuel crops, such as switchgrass (Panicum virgatum L.), that produce their own cell wall-digesting cellulase enzymes would reduce costs of cellulosic biofuel production. To date, non-bioenergy plant models have been used in nearly all studies assessing the synthesis and activity of plant-produced fungal and bacterial cellulases. One potential source for cellulolytic enzyme genes is herbivorous insects adapted to digest plant cell walls. Here we examine the potential of transgenic switchgrass-produced TcEG1 cellulase from Tribolium castaneum (red flour beetle). This enzyme, when overproduced in Escherichia coliand Saccharomyces cerevisiae, efficiently digests cellulose at optima of 50 …

Field-Grown Mir156 Transgenic Switchgrass Reproduction, Yield, Global Gene Expression Analysis, And Bioconfinement, Chelsea R. Johnson, Reginald J. Millwood, Yuhong Tang, Jiqing Gou, Robert W. Sykes, Geoffrey B. Turner, Mark F. Davis, Yi Sang, Zeng-Yu Wang, C. Neal Stewart Jr

Plant Sciences Publications and Other Works

Background

Genetic engineering has been effective in altering cell walls for biofuel production in the bioenergy crop, switchgrass (Panicum virgatum). However, regulatory issues arising from gene flow may prevent commercialization of engineered switchgrass in the eastern United States where the species is native. Depending on its expression level, microRNA156 (miR156) can reduce, delay, or eliminate flowering, which may serve to decrease transgene flow. In this unique field study of transgenic switchgrass that was permitted to flower, two low (T14 and T35) and two medium (T27 and T37) miR156-overexpressing ‘Alamo’ lines with the transgene under the control of the …

Light And Temperature Effects On Mir156 Transgenic Switchgrass Flowering: A Simulated Latitudinal Study, Chelsea R. Johnson, Reginald J. Millwood, Zeng-Yu Wang, Neal Stewart

Plant Sciences Publications and Other Works

The control of flowering in perennial grasses is an important trait, especially among biofuel feedstocks. Lignocellulosic biomass may be increased commensurate with decreased or delayed flowering as the plant allocates energy for stems and leaves harvested for bioenergy at the end of the growing season. For transgenic feedstocks, such as switchgrass (Panicum virgatum L.) grown in its geographic center of distribution, it is foreseeable that regulators may require greatly decreased gene flow frequencies to enable commercialization. Transgenic switchgrass with various overexpression levels of a rice microRNA gene, miR156, when grown in field conditions, holds promise for decreased flowering, yielding …

Transgenic Mir156 Switchgrass In The Field: Growth, Recalcitrance And Rust Susceptibility, Holly L. Baxter, Mitra Mazarei, Alexandru Dumitrache, Jace M. Natzke, Miguel Rodriguez Jr, Jiqing Gou, Chunxiang Fu, Robert W. Sykes, Geoffrey B. Turner, Mark F. Davis, Steven D. Brown, Brian H. Davison, Zen-Yu Wang, C. Neal Stewart Jr

Plant Sciences Publications and Other Works

Sustainable utilization of lignocellulosic perennial grass feedstocks will be enabled by high biomass production and optimized cell wall chemistry for efficient conversion into biofuels. MicroRNAs are regulatory elements that modulate the expression of genes involved in various biological functions in plants, including growth and development. In greenhouse studies, overexpressing a microRNA (miR156) gene in switchgrass had dramatic effects on plant architecture and flowering, which appeared to be driven by transgene expression levels. Highexpressing lines were extremely dwarfed, whereas low and moderate-expressing lines had higher biomass yields, improved sugar release and delayed flowering. Four lines with moderate or low miR156 overexpression …

The Potential Of Systems Biology To Discover Antibacterial Mechanisms Of Plant Phenolics, Caroline S. Rempe, Kellie P. Burris, Scott C. Lenaghan, C. Neal Stewart Jr.

Plant Sciences Publications and Other Works

Drug resistance of bacterial pathogens is a growing problem that can be addressed through the discovery of compounds with novel mechanisms of antibacterial activity. Natural products, including plant phenolic compounds, are one source of diverse chemical structures that could inhibit bacteria through novel mechanisms. However, evaluating novel antibacterial mechanisms of action can be difficult and is uncommon in assessments of plant phenolic compounds. With systems biology approaches, though, antibacterial mechanisms can be assessed without the bias of target-directed bioassays to enable the discovery of novel mechanism(s) of action against drug resistant microorganisms. This review article summarizes the current knowledge of …

Increased Salt Tolerance With Overexpression Of Cation/Proton Antiporter 1 Genes: A Meta-Analysis, Yuan-Chun Ma, Robert M. Augé, Chao Dong, Zong-Ming (Max) Cheng

Plant Sciences Publications and Other Works

Cation/proton antiporter 1 (CPA1) genes encode cellular Na+/H+ exchanger proteins, which act to adjust ionic balance. Overexpression of CPA1s can improve plant performance under salt stress. However, the diversified roles of the CPA1 family and the various parameters used in evaluating transgenic plants over-expressing CPA1s make it challenging to assess the complex functions of CPA1s and their physiological mechanisms in salt tolerance. Using meta-analysis, we determined how overexpression of CPA1s has influenced several plant characteristics involved in response and resilience to NaCl stress. We also evaluated experimental variables that favor or reduce CPA1 effects in transgenic plants. Viewed across studies, …

An (E,E)-Α-Farnesene Synthase Gene Of Soybean Has A Role In Defence Against Nematodes And Is Involved In Synthesizing Insect-Induced Volatiles, Jingyu Lin, Daniel Wang, Xinlu Chen, Tobias G. Köllerner, Mitra Mazarei, Hong Guo, Vincent R. Pantalone, Prakash Arelli, Charles Neal Stewart Jr., Ningning Wang, Feng Chen

Plant Sciences Publications and Other Works

Plant terpene synthase genes (TPSs) have roles in diverse biological processes. Here, we report the functional characterization of one member of the soybean TPS gene family, which was designated GmAFS. Recombinant GmAFS produced in Escherichia coli catalysed the formation of a sesquiterpene (E,E)-a-farnesene. GmAFS is closely related to (E,E)-a-farnesene synthase gene from apple, both phylogenetically and structurally. GmAFS was further investigated for its biological role in defence against nematodes and insects. Soybean cyst nematode (SCN) is the most important pathogen of soybean. The expression of GmAFS in a SCN-resistant soybean was significantly induced by SCN infection compared with the control, …