Download or read book Evaluation of Hall s Panicgrass Panicum Hallii Vasey as a Model System for Genetic Modification of Recalcitrance in Switchgrass Panicum Virgatum L written by Joshua Nathaniel Grant and published by . This book was released on 2017 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt: While switchgrass (Panicum virgatum (L.)) has long been recognized as a viable bioenergy feedstock, it and other plants have cell walls with recalcitrance to processing. Recalcitrance is recognized as a major barrier to broad adoption of switchgrass and other feedstocks for cellulosic bioenergy. In an effort to reduce recalcitrance, transgenic plants have been generated with altered cell wall phenotypes such as reduced lignin. Unfortunately, stable transformation of switchgrass and other C4 grasses is time intensive, costly, and genetic analysis is further complicated by polyploid genomic structures. Unlike switchgrass, which can be tetraploid to octoploid, a closely related species, Hall’s panicgrass (Panicum hallii Vasey), is diploid, and has a much smaller genome. In addition, Hall’s panicgrass is a smaller plant with a faster generation time and is capable of self-fertilization. In the present study, germplasm from two inbred populations of Hall’s panicgrass, FIL2 and HAL2, were selected to assess the feasibility of using Hall’s panicgrass as a model for switchgrass. Included in this work was the development of methods using seeds immediately harvested from plants grown in the greenhouse for germination, sterilization, callus induction, transformation, and regeneration. Seed germination was optimized on NB medium at 70 ±[plus or minus] 11% for FIL2 and 82 ±[plus or minus]3.0% for HAL2. Callus induction was optimized on MS-OG medium at 51 ±[plus or minus]29% and 81 ±[plus or minus]19% for HAL2. Shoot regeneration was optimized on REG medium at 11.5± [plus or minus] 0.8 shoots/gram for FIL2 and 11.3 ±[plus or minus]0.6 shoots/gram for HAL2. Root regeneration occurred at 100% frequency for all callus expressing roots on Diet-MSO. In addition to a complete tissue culture system, a suspension culture system was also developed to more rapidly produce tissue for cell-based experiments. Cell suspensions of Hall’s panicgrass, both FIL2 and HAL2, generated more callus after 16 weeks of culture (141 ±[plus or minus] 22% for FIL2; 302 ±[plus or minus] 54% for HAL2) than the solid-medium culture system.

Download or read book Genetic Modification of Switchgrass Panicum Virgatum L for Improvement of Plant Architecture Biomass Productivity and Sugar Release Efficiency for Biofuel written by Wegi Aberra Wuddineh and published by . This book was released on 2015 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: Switchgrass (Panicum virgatum L.) is a leading candidate bioenergy crop for sustainable biofuel production. To ensure its economic viability, tremendous improvements in switchgrass biomass productivity and recalcitrance to enzymatic saccharification are needed. Genetic manipulation of lignin biosynthesis by targeting transcriptional regulators of higher level domains of lignin biosynthesis and other complex traits could alter several bioenergy-desirable traits at once. A three-pronged approach was made in the dissertation research to target one plant growth regulator and transcription factors to alter plant architecture a nd cell wall biosynthesis. Gibberellin (GA) catabolic enzymes, GA 2-oxidases (GA2oxs), were utilized to alternatively modify the lignin biosynthesis pathway as GA is known to play a role in plant lignification. Constitutive overexpression of switchgrass C20 [C20] GA2ox genes altered plant morphology and modified plant architecture by increasing the number of tillers. Moreover, transgenic plants exhibited reduced lignin especially in leaves accompanied by 15% increase in sugar release (glucose). The Knotted1 (PvKN1) TF, a putative repressor of lignin biosynthesis genes, was identified and evaluated for improving biomass characteristics of switchgrass for biofuel. Its ectopic overexpression in switchgrass altered the expression of genes in the lignin, cellulose and hemicellulose biosynthesis, and GA signalling pathways. Consequently, transgenic lines displayed altered growth phenotypes particularly at early stages of vegetative development and moderate changes in lignin content accompanied by improved sugar release by up to 16%. The APETALA2/ ethylene responsive factor (AP2/ERF) TFs are key putative targets for engineering plants not only so they can withstand adverse environmental factors but also confer modified cell wall characteristics. To facilitate this, a total of 207 switchgrass AP2/ERF TFs comprising 3 families (AP2, ERF and related to API3/VP (RAV)) were identified. Sequence analysis for conserved putative motifs and expression pattern analysis delimited key genes for manipulation of switchgrass. To that end, the PvERF001 TF gene was ectopically overexpressed resulting in improved biomass yield and sugar release efficiency. The transgenic plants and knowledge produced in this research will be used to create new lines of switchgrass with combined novel traits to address needs in biofuel production and sustainable plant cultivation to enable the development of the bioeconomy.

Download or read book Transgenic Switchgrass Panicum Virgatum L Targeted for Reduced Recalcitrance to Bioconversion written by and published by . This book was released on 2016 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Five different types of transgenic (GAUT4, miRNA, MYB4, COMT and FPGS) Panicum virgatum L. (switchgrass) were grown in a field in Knoxville, Tenn., USA over two consecutive years between 2011 and 2015 in separate experiments. Clonal replicates were established (year-one) and produced much greater biomass during the second year. After each growing season the above ground biomass was analyzed for cell wall sugars and for recalcitrance to enzymatic digestibility, and biofuel using a separate hydrolysis and fermentation (SHF) screen. Here, each transgenic event and control had more glucan, xylan and less ethanol (g/g basis) from the second year of growth relative to the first year plants. There was no correlation between plant carbohydrate content and biofuel production. In each of cell wall-targeted transgenics, GAUT4, MYB4, COMT and FPGS, the second year of growth resulted in increased carbohydrate abundance (up to 12%) and reduced recalcitrance through higher ethanol yields (up to 21%) over the non-transgenic control plants.

Download or read book Switchgrass Panicum Virgatum L Distribution Genetic Diversity and Pollen mediated Gene Flow written by and published by . This book was released on 2014 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Switchgrass Panicum Virgatum L Distribution Genetic Diversity and Pollen mediated Gene Flow written by Geoffrey Isaac Ecker and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Genetic Improvement of Biomass Yield in Upland Switchgrass Panicum Virgatum L Using Secondary Plant Morphological Traits written by and published by . This book was released on 2013 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt: Switchgrass (Panicum virgatum L.) is currently undergoing intensive breeding efforts to improve biomass yield. Direct selection for biomass yield in switchgrass has proven difficult due to the many factors influencing biomass yield. In developing breeding schemes for increasing biomass yield, consideration must be made to the relative importance of spaced plantings to sward plots for evaluation and selection. It has previously been suggested that selection schemes using secondary plant morphological traits as selection criteria within spaced plantings may be an efficient method of making genetic gain. This research sought to identify secondary morphological traits in parental plants that are predictive of biomass yield in progeny swards, estimate heritability of secondary morphological traits and empirically test the effects of direct selection for secondary morphological traits on biomass yield. Limited predictive ability was observed for sward biomass yield using individual and combinations of plant morphological traits. A comparison of models using a Bayesian model averaging approach revealed common traits among the best predictive models including plant height, single-plant dry biomass, and second leaf width. Predictions of single-plant biomass, using the same set of morphological traits, revealed a large effect for tillering related traits. Moderate heritability was estimated for plant height and was greater for selection of increased height. Heritability for tiller count was low overall, with greater values observed for reduced tillering selections. Flowering date was estimated to have high heritability overall in both selection directions. Divergently selected populations for each trait were developed from the WS4U upland tetraploid germplasm and evaluated for biomass yield at five locations in Wisconsin during two growing seasons. Significant variation was observed between maternal parents of the selected populations for both selected and non-selected traits. Despite substantial differences between parent plant populations for plant morphology, significant differences were not observed for sward-plot biomass yield or sward-plot morphology relative to the base population. Results of this research demonstrate the challenges of selecting for increased biomass yield in switchgrass within spaced-plant nurseries. Based on these results it is recommended that greater emphasis be placed on evaluation biomass yield within sward plots for improving biomass yield.

Download or read book Estimation of Genetic Parameters in Several Switchgrass Panicum Virgatum L Populations written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Evaluating the Agronomic Performance of Switchgrass Panicum Virgatum L on Marginal Vs Prime Farmland written by Sergio J. Sosa and published by . This book was released on 2013 with total page 219 pages. Available in PDF, EPUB and Kindle. Book excerpt: Switchgrass (Panicum virgatum L.) is a warm-season perennial grass native to North America. The difference in biomass production between and within switchgrass ecotypes (upland and lowland) and populations due to genotype x environment interaction (GxE) has been documented. Breeding research for increased biomass production in switchgrass has been conducted on University research farms with prime farmland. This study aims to evaluate the agronomic performance of 14 cultivars and 45 high biomass producing clones of switchgrass in marginal vs. prime farmland. Additionally this study investigates the effects of increasing biodiversity (1 grass species, 3 grass species or 4 species-grass/legume combinations) on biomass production. The cultivars and biodiversity studies were seeded in 2008 and 2009 in six locations (Maryland, New Jersey, New York, Pennsylvania, South Dakota and Wisconsin) and three locations (New Jersey, New York, Pennsylvania), respectively, in paired fields (marginal vs. prime land). Each field had a nitrogen treatment 0 or 100 kg of N·ha-1·year-1. Stand establishment (% coverage), plant height (cm), tiller density (tillers·m-2) and dry biomass yield (Mg·ha-1) data was collected to determine agronomic performance. The clonal material was transplanted in 2009 in two locations (New Jersey and South Dakota). In addition to agronomic data collected, heading date, anthesis date (Julian date) and visual ratings for disease presence were recorded. Cultivars were shorter in marginal soils. For stand establishment and biomass yield, 50% of cultivars showed differences due to soil quality. For tiller density, 40% of the cultivars presented differences due to soil quality; some cultivars had higher tiller density in marginal soils. For the biodiversity study low diversity plots (one grass species) were not significantly different than yields of high diversity plots (four species-grass/legume). For the clone study, soil quality may have influenced a delay in flower initiation and other traits, such as plant height, etc. It was also observed that genotype may have been the most influential factor in tolerance to anthracnose (Colletotrichum navitas) and rust (Puccinia emaculata).