Development and use of a switchgrass (Panicum virgatum L.) transformation pipeline by the BioEnergy Science Center to evaluate plants for reduced cell wall recalcitrance

Abstract

BackgroundThe mission of the BioEnergy Science Center (BESC) was to enable efficient lignocellulosic-based biofuel production. One BESC goal was to decrease poplar and switchgrass biomass recalcitrance to biofuel conversion while not affecting plant growth. A transformation pipeline (TP), to express transgenes or transgene fragments (constructs) in these feedstocks with the goal of understanding and decreasing recalcitrance, was considered essential for this goal. Centralized data storage for access by BESC members and later the public also was essential.ResultsA BESC committee was established to codify procedures to evaluate and accept genes into the TP. A laboratory information management system (LIMS) was organized to catalog constructs, plant lines and results from their analyses. One hundred twenty-eight constructs were accepted into the TP for expression in switchgrass in the first 5 years of BESC. Here we provide information on 53 of these constructs and the BESC TP process. Eleven of the constructs could not be cloned into an expression vector for transformation. Of the remaining constructs, 22 modified expression of the gene target. Transgenic lines representing some constructs displayed decreased recalcitrance in the field and publications describing these results are tabulated here. Transcript levels of target genes and detailed wall analyses from transgenic lines expressing six additional tabulated constructs aimed toward modifying expression of genes associated with wall structure (xyloglucan and lignin components) are provided. Altered expression of xyloglucan endotransglucosylase/hydrolases did not modify lignin content in transgenic plants. Simultaneous silencing of two hydroxycinnamoyl CoA:shikimate hydroxycinnamoyl transferases was necessary to decrease G and S lignin monomer and total lignin contents, but this reduced plant growth.ConclusionsA TP to produce plants with decreased recalcitrance and a LIMS for data compilation from these plants were created. While many genes accepted into the TP resulted in transgenic switchgrass without modified lignin or biomass content, a group of genes with potential to improve lignocellulosic biofuel yields was identified. Results from transgenic lines targeting xyloglucan and lignin structure provide examples of the types of information available on switchgrass lines produced within BESC. This report supplies useful information when developing coordinated, large-scale, multi-institutional reverse genetic pipelines to improve crop traits.Electronic supplementary materialThe online version of this article (10.1186/s13068-017-0991-x) contains supplementary material, which is available to authorized users.

Assessment of shared alleles in drought-associated candidate genes among southern California white oak species (Quercus sect. Quercus)

“…There were many interesting potential functions amongst this narrowed down set, which include several sugar transporters, two separate homologs to coumarate-coA ligases, two genes involved in glutathione S-conjugation, and several stress response genes. Other studies have found other genes such as FBA1 [ 52 ], BURP [ 53 , 54 ], USP [ 55 ], GH16_XET [ 56 ], CYP707 gene family [ 57 ], HSF [ 58 ], AAI_LTSS [ 59 ] (Additional file 1 : Table S1) to be involved in drought resistance that we would have expected to be important in this study but did not show species-specific signatures in this study. The genes we report these here so that future studies of local adaptation might use them for comparison.…”

Silencing Folylpolyglutamate Synthetase1 (FPGS1) in Switchgrass (Panicum virgatum L.) Improves Lignocellulosic Biofuel Production

“…Cell wall lignin is one of the main causes of recalcitrance, which limits efficient conversion of biomass into biofuels (Chen and Dixon, 2007;David and Ragauskas, 2010). Cell wall components have been key targets to reduce feedstock recalcitrance; manipulating cell wall biosynthesis gene expression has been the primary strategy (Nelson et al, 2017;Biswal et al, 2018;Brandon and Scheller, 2020). Several studies with transgenic plants have been conducted in greenhouses under tightly controlled environmental conditions and the actively growing green tissue has been analyzed most often (Fu et al, 2011a(Fu et al, ,b, 2012Xu et al, 2011;Shen et al, 2012Shen et al, , 2013Liu et al, 2018).…”

Exploring the prospective of weeds (Cannabis sativa L., Parthenium hysterophorus L.) for biofuel production through nanocatalytic (Co, Ni) gasification

“…[ 6 ], Prosopis spp. [ 7 ], Parthenium hysterophorus L. [ 8 ], Cannabis sativa L. [ 9 ], Panicum virgatum L. [ 10 , 11 ] and Arundo donax L. [ 12 ].…”