Yield performance of 14 novel inter- and intra-species Miscanthus hybrids across Europe

Funding information Bio-Based Industries Joint Undertaking, Grant/Award Number: 745012 ACKNOWLEDGEMENTS For additional information and data collection many thanks to Oberer Lindenhof field station staff (OLI), Unifarm workers (SCH), experimental station Šašinovec technical stuff (ZAG). The authors are grateful for the support of the staff at the research stations at PAC. With particular thanks at the Trawsgoed site (TWS) to Robin Warren, Chris Glover, and the late Kevin Roderick. Thanks also to Michael Squance for use of and assistance with the Physis™ data management platform. FUNDING INFORMATION The GRACE project has received funding from the Bio-based Industries Joint Undertaking (JU) under the European Union's Horizon 2020 research and innovation programme under grant agreement no. 745012. The JU receives support from the European Union's Horizon 2020 research and innovation programme and the Bio-based Industries Consortium.Peer reviewedPublisher PD

Breeding Targets to Improve Biomass Quality in Miscanthus

Lignocellulosic crops are attractive bioresources for energy and chemicals production within a sustainable, carbon circular society. Miscanthus is one of the perennial grasses that exhibits great potential as a dedicated feedstock for conversion to biobased products in integrated biorefineries. The current biorefinery strategies are primarily focused on polysaccharide valorization and require severe pretreatments to overcome the lignin barrier. The need for such pretreatments represents an economic burden and impacts the overall sustainability of the biorefinery. Hence, increasing its efficiency has been a topic of great interest. Inversely, though pretreatment will remain an essential step, there is room to reduce its severity by optimizing the biomass composition rendering it more exploitable. Extensive studies have examined the miscanthus cell wall structures in great detail, and pinpointed those components that affect biomass digestibility under various pretreatments. Although lignin content has been identified as the most important factor limiting cell wall deconstruction, the effect of polysaccharides and interaction between the different constituents play an important role as well. The natural variation that is available within different miscanthus species and increased understanding of biosynthetic cell wall pathways have specified the potential to create novel accessions with improved digestibility through breeding or genetic modification. This review discusses the contribution of the main cell wall components on biomass degradation in relation to hydrothermal, dilute acid and alkaline pretreatments. Furthermore, traits worth advancing through breeding will be discussed in light of past, present and future breeding efforts.</p

Investigating applied drought in Miscanthus sinensis; sensitivity, response mechanisms, and subsequent recovery

Miscanthus is renowned for its excellent water-use efficiency and good adaptability to a wide range of environmental conditions, making it suitable for cultivation on marginal soils. Drought is a major cause of this marginality, and its occurrence is becoming more frequent and prolonged due to climatic change. Developing drought tolerant genotypes of miscanthus would ensure the maintenance of economically viable yields on lands prone to periodic water-deficiency. To better understand the underlying response and tolerance mechanisms, pre-screen for better survivability at plot setup on marginal lands, and identifying early biomarkers of stress, we explored the genetic diversity present in Miscanthus sinensis under applied drought. Young plants of 23 genotypes underwent 3 weeks of water-deprivation in glasshouse-controlled conditions, followed by an equal period of recovery. Leaves harvested at the end of both experimental phases were the focus of extensive biochemical analyses. Coupled with monitoring several growth and yield parameters, this was instrumental in evaluating stress impact and responses. The most productive genotypes suffered the most in terms of yield reduction and chlorophyll degradation when stress was applied. In parallel, proline and simple soluble sugars accumulated to readjust the osmotic potential in the cytosol and vacuoles, respectively. The necessary carbon skeletons for this buildup were partially acquired from resources diverted away from cell wall synthesis and maintenance, whose content dropped under stress in parallel to increasing drought-sensitivity. Correspondingly, expressional and biochemical analyses revealed a dynamic turnover of starch and soluble sugars in stressed leaves. Meanwhile, better avoidance of stress enabled a more efficient post-drought recovery, which was characterized by restoring pre-stress hydraulic status and unplugging stress response mechanisms

Syntenic Cell Wall QTLs as Versatile Breeding Tools: Intraspecific Allelic Variability and Predictability of Biomass Quality Loci in Target Plant Species

Syntenic cell wall QTLs (SQTLs) can identify genetic determinants of biomass traits in understudied species based on results from model crops. However, their effective use in plant breeding requires SQTLs to display intraspecific allelic variability and to predict causative loci in other populations/species than the ones used for SQTLs identification. In this study, genome assemblies from different accessions of Arabidopsis, rapeseed, tomato, rice, Brachypodium and maize were used to evaluate the intraspecific variability of SQTLs. In parallel, a genome-wide association study (GWAS) on cell wall quality traits was performed in miscanthus to verify the colocalization between GWAS loci and miscanthus SQTLs. Finally, an analogous approach was applied on a set of switchgrass cell wall QTLs retrieved from the literature. These analyses revealed large SQTLs intraspecific genetic variability, ranging from presence–absence gene variation to SNPs/INDELs and changes in coded proteins. Cell wall genes displaying gene dosage regulation, such as PAL and CAD, displayed presence–absence variation in Brachypodium and rapeseed, while protein INDELs were detected for the Brachypodium homologs of the rice brittle culm-like 8 locus, which may likely impact cell wall quality. Furthermore, SQTLs significantly colocalized with the miscanthus and switchgrass QTLs, with relevant cell wall genes being retained in colocalizing regions. Overall, SQTLs are useful tools to screen germplasm for relevant genes and alleles to improve biomass quality and can increase the efficiency of plant breeding in understudied biomass crops

Syntenic Cell Wall QTLs as Versatile Breeding Tools: Intraspecific Allelic Variability and Predictability of Biomass Quality Loci in Target Plant Species

Syntenic cell wall QTLs (SQTLs) can identify genetic determinants of biomass traits in understudied species based on results from model crops. However, their effective use in plant breeding requires SQTLs to display intraspecific allelic variability and to predict causative loci in other populations/species than the ones used for SQTLs identification. In this study, genome assemblies from different accessions of Arabidopsis, rapeseed, tomato, rice, Brachypodium and maize were used to evaluate the intraspecific variability of SQTLs. In parallel, a genome-wide association study (GWAS) on cell wall quality traits was performed in miscanthus to verify the colocalization between GWAS loci and miscanthus SQTLs. Finally, an analogous approach was applied on a set of switchgrass cell wall QTLs retrieved from the literature. These analyses revealed large SQTLs intraspecific genetic variability, ranging from presence&ndash;absence gene variation to SNPs/INDELs and changes in coded proteins. Cell wall genes displaying gene dosage regulation, such as PAL and CAD, displayed presence&ndash;absence variation in Brachypodium and rapeseed, while protein INDELs were detected for the Brachypodium homologs of the rice brittle culm-like 8 locus, which may likely impact cell wall quality. Furthermore, SQTLs significantly colocalized with the miscanthus and switchgrass QTLs, with relevant cell wall genes being retained in colocalizing regions. Overall, SQTLs are useful tools to screen germplasm for relevant genes and alleles to improve biomass quality and can increase the efficiency of plant breeding in understudied biomass crops

Syntenic Cell Wall QTLs as Versatile Breeding Tools: Intraspecific Allelic Variability and Predictability of Biomass Quality Loci in Target Plant Species

Syntenic cell wall QTLs (SQTLs) can identify genetic determinants of biomass traits in understudied species based on results from model crops. However, their effective use in plant breeding requires SQTLs to display intraspecific allelic variability and to predict causative loci in other populations/species than the ones used for SQTLs identification. In this study, genome assemblies from different accessions of Arabidopsis, rapeseed, tomato, rice, Brachypodium and maize were used to evaluate the intraspecific variability of SQTLs. In parallel, a genome-wide association study (GWAS) on cell wall quality traits was performed in miscanthus to verify the colocalization between GWAS loci and miscanthus SQTLs. Finally, an analogous approach was applied on a set of switchgrass cell wall QTLs retrieved from the literature. These analyses revealed large SQTLs intraspecific genetic variability, ranging from presence–absence gene variation to SNPs/INDELs and changes in coded proteins. Cell wall genes displaying gene dosage regulation, such as PAL and CAD, displayed presence–absence variation in Brachypodium and rapeseed, while protein INDELs were detected for the Brachypodium homologs of the rice brittle culm-like 8 locus, which may likely impact cell wall quality. Furthermore, SQTLs significantly colocalized with the miscanthus and switchgrass QTLs, with relevant cell wall genes being retained in colocalizing regions. Overall, SQTLs are useful tools to screen germplasm for relevant genes and alleles to improve biomass quality and can increase the efficiency of plant breeding in understudied biomass crops

Plant Genotype and Fungal Strain Harmonization Improves Miscanthus sinensis Conversion by the White-Rot Fungus Ceriporiopsis subvermispora

Fungal pretreatment of plant biomass is often assessed by using single plant genotypes and single fungal strains, but can the process be improved by harmonizing both, thus selecting specific substrate-fungus combinations? To tackle this question, we treated four Miscanthus sinensis genotypes with four Ceriporiopsis subvermispora strains and thoroughly analyzed substrates and treated residues. The M. sinensis genotypes differed in cellulose, hemicellulose, and lignin contents and lignin-wise diverged in subunit and linkage composition and the incorporation of hydroxycinnamic acids and tricin. Independently of the M. sinensis genotype used, C. subvermispora strain MES13904 outperformed the other three strains in extent and selectivity of delignification and consistently generated the highest enzymatic residual carbohydrate conversion and structural changes in the residual lignin. The “best” substrate-fungus combination gave 63% w/w delignification and a total enzymatic glucose yield of 66% w/w, while the “worst” combination led to 3% w/w lignin removal only and negligible glucose yield improvement. Our study highlights that white-rot fungal treatment of plant biomass is driven by both compositional and structural features of the substrate as well as the genetic makeup of the fungal strain used. These insights contribute to expediting the biological valorization of lignocellulose and ultimately to enabling more controlled fungal pretreatments

Plant Genotype and Fungal Strain Harmonization Improves Miscanthus sinensis Conversion by the White-Rot Fungus Ceriporiopsis subvermispora

Fungal pretreatment of plant biomass is often assessed by using single plant genotypes and single fungal strains, but can the process be improved by harmonizing both, thus selecting specific substrate–fungus combinations? To tackle this question, we treated four Miscanthus sinensis genotypes with four Ceriporiopsis subvermispora strains and thoroughly analyzed substrates and treated residues. The M. sinensis genotypes differed in cellulose, hemicellulose, and lignin contents and lignin-wise diverged in subunit and linkage composition and the incorporation of hydroxycinnamic acids and tricin. Independently of the M. sinensis genotype used, C. subvermispora strain MES13904 outperformed the other three strains in extent and selectivity of delignification and consistently generated the highest enzymatic residual carbohydrate conversion and structural changes in the residual lignin. The “best” substrate–fungus combination gave 63% w/w delignification and a total enzymatic glucose yield of 66% w/w, while the “worst” combination led to 3% w/w lignin removal only and negligible glucose yield improvement. Our study highlights that white-rot fungal treatment of plant biomass is driven by both compositional and structural features of the substrate as well as the genetic makeup of the fungal strain used. These insights contribute to expediting the biological valorization of lignocellulose and ultimately to enabling more controlled fungal pretreatments

Novel Miscanthus hybrids:Modelling productivity on marginal land in Europe using dynamics of canopy development determined by light interception

ACKNOWLEDGEMENTS We would like to thank the industry partner Terravesta, developers of Miscanthus throughout the UK, the Dutch company Van Dinter Semo, developers of M. sin × sin hybrids, and all collaborators and the members of the GRACE project funded by the Bio-based Industries Joint Undertaking, grant agreement no. 745012. The authors thank EPSRC, BBSRC and UK Supergen Bioenergy Hub (EP/S000771/1) who funded and supported this research. The work was made possible by a Supergen Bioenergy hub fellowship, funding ref. RG15855—UKRI (EPSRC) via Aston University and the survey was carried out as part of project SUMMER—seed-propagated upscaling of Miscanthus—modelling and environmental response. This work was also made possible by BBSRC funding (BB/V011553/1) for the Perennial Biomass Crops for Greenhouse Gas Removal (PBC4GGR) Demonstrator project, and was also undertaken as part of the UK Energy Research Centre research programme. Funded by the UK Research and Innovation Energy Programme under grant number EP/S029575/1.Peer reviewedPublisher PD

Novel Miscanthus hybrids : Modelling productivity on marginal land in Europe using dynamics of canopy development determined by light interception

New biomass crop hybrids for bioeconomic expansion require yield projections to determine their potential for strategic land use planning in the face of global challenges. Our biomass growth simulation incorporates radiation interception and conversion efficiency. Models often use leaf area to predict interception which is demanding to determine accurately, so instead we use low-cost rapid light interception measurements using a simple laboratory-made line ceptometer and relate the dynamics of canopy closure to thermal time, and to measurements of biomass. We apply the model to project the European biomass potentials of new market-ready hybrids for 2020–2030. Field measurements are easier to collect, the calibration is seasonally dynamic and reduces influence of weather variation between field sites. The model obtained is conservative, being calibrated by crops of varying establishment and varying maturity on less productive (marginal) land. This results in conservative projections of miscanthus hybrids for 2020–2030 based on 10% land use conversion of the least (productive) grassland and arable for farm diversification, which show a European potential of 80.7–89.7 Mt year−1 biomass, with potential for 1.2–1.3 EJ year−1 energy and 36.3–40.3 Mt year−1 carbon capture, with seeded Miscanthus sacchariflorus × sinensis displaying highest yield potential. Simulated biomass projections must be viewed in light of the field measurements on less productive land with high soil water deficits. We are attempting to model the results from an ambitious and novel project combining new hybrids across Europe with agronomy which has not been perfected on less productive sites. Nevertheless, at the time of energy sourcing issues, seed-propagated miscanthus hybrids for the upscaled provision of bioenergy offer an alternative source of renewable energy. If European countries provide incentives for growers to invest, seeded hybrids can improve product availability and biomass yields over the current commercial miscanthus variety