Dedicated Biomass Crops Research Articles

Salt tolerance evaluation and mini-core collection development in Miscanthus sacchariflorus and M. lutarioriparius.

Marginal lands, such as those with saline soils, have potential as alternative resources for cultivating dedicated biomass crops used in the production of renewable energy and chemicals. Optimum utilization of marginal lands can not only alleviate the competition for arable land use with primary food crops, but also contribute to bioenergy products and soil improvement. Miscanthus sacchariflorus and M. lutarioriparius are prominent perennial plants suitable for sustainable bioenergy production in saline soils. However, their responses to salt stress remain largely unexplored. In this study, we utilized 318 genotypes of M. sacchariflorus and M. lutarioriparius to assess their salt tolerance levels under 150 mM NaCl using 14 traits, and subsequently established a mini-core elite collection for salt tolerance. Our results revealed substantial variation in salt tolerance among the evaluated genotypes. Salt-tolerant genotypes exhibited significantly lower Na+ content, and K+ content was positively correlated with Na+ content. Interestingly, a few genotypes with higher Na+ levels in shoots showed improved shoot growth characteristics. This observation suggests that M. sacchariflorus and M. lutarioriparius adapt to salt stress by regulating ion homeostasis, primarily through enhanced K+ uptake, shoot Na+ exclusion, and Na+ sequestration in shoot vacuoles. To evaluate salt tolerance comprehensively, we developed an assessment value (D value) based on the membership function values of the 14 traits. We identified three highly salt-tolerant, 50 salt-tolerant, 127 moderately salt-tolerant, 117 salt-sensitive, and 21 highly salt-sensitive genotypes at the seedling stage by employing the D value. A mathematical evaluation model for salt tolerance was established for M. sacchariflorus and M. lutarioriparius at the seedling stage. Notably, the mini-core collection containing 64 genotypes developed using the Core Hunter algorithm effectively represented the overall variability of the entire collection. This mini-core collection serves as a valuable gene pool for future in-depth investigations of salt tolerance mechanisms in Miscanthus.

The performance of Miscanthus hybrids in saline-alkaline soil.

Cultivating the dedicated biomass crop Miscanthus on marginal land is a sustainable means of avoiding competition with food crops for arable land. A large proportion of global marginal land is saline–alkaline; however, little is known about the performance of Miscanthus in saline-alkaline soil. In this study, Miscanthus × giganteus and ten other Miscanthus hybrids grown in the Yellow River Delta were exposed to low and saline–alkaline soils during the 2016–2018 growing season to evaluate the agronomic traits, biomass quality and the potential productive index of eleven Miscanthus genotypes. Plant biomass, plant height, and tiller number significantly decreased in high saline–alkaline soil. In particular, the average plant biomass of ten Miscanthus hybrids in low saline–alkaline soil in 2017 and 2018 were 0.21 and 2.25 kg per plant, respectively, and in high saline-alkaline soil were 0.13 and 0.65 kg per plant, respectively. Cell wall, cellulose, and nitrogen content of all genotypes significantly decreased in high saline–alkaline soil, while hemicellulose, ash, sodium, potassium, magnesium, and calcium content significantly increased. However, high saline–alkaline soil had no observable impact on lignin content of Miscanthus biomass. The effect of high saline-alkaline on biomass quality parameters could provide important information for the application of Miscanthus biomass in saline-alkaline soil. The selected genotypes (A5) could be considered as breeding materials in saline-alkaline soil.

Revisiting “Additional Carbon”: Tracking Atmosphere–Ecosystem Carbon Exchange to Establish Mitigation and Negative Emissions From Bio-Based Systems

Climate stabilization plans rely heavily on advanced bioenergy and bioproducts for substitution of fossil-based energy sources and materials, and increasingly, for negative emissions via the direct sequestration of biogenic carbon. Yet, there remain persistent, largely unresolved critiques of bioenergy assessment methodology, particularly in the areas of land use and biogenic carbon accounting. The concept of “additional carbon” calls for evaluating the climate performance of bio-based systems by whether feedstock production creates measurable new local agro-ecosystem uptake of carbon from the atmosphere. This concept is challenging to operationalize for first-generation biofuels, and has largely been advanced as a negative critique. However, carbon additionality is more straightforward to establish—and less critical to overall system mitigation performance—in advanced bioenergy systems. In this Perspective, I review the additional carbon critique, and why it is analytically challenging to address in first-generation biofuel systems based on conventional food crops with large existing markets. Next, I make a case that carbon additionality (1) is more readily achievable with cellulosic feedstocks, (2) is more directly observable for dedicated biomass crops, and (3) is not a strict requirement for achieving net mitigation in carbon-negative bio-based systems. I end by discussing how centering atmosphere–ecosystem carbon exchanges in bio-based system assessment could create new opportunities for enterprise-scale performance monitoring and verification, augmenting and diversifying the current reliance on model-based life-cycle assessment approaches.

Marginal Lands to Grow Novel Bio-Based Crops: A Plant Breeding Perspective.

The biomass demand to fuel a growing global bio-based economy is expected to tremendously increase over the next decades, and projections indicate that dedicated biomass crops will satisfy a large portion of it. The establishment of dedicated biomass crops raises huge concerns, as they can subtract land that is required for food production, undermining food security. In this context, perennial biomass crops suitable for cultivation on marginal lands (MALs) raise attraction, as they could supply biomass without competing for land with food supply. While these crops withstand marginal conditions well, their biomass yield and quality do not ensure acceptable economic returns to farmers and cost-effective biomass conversion into bio-based products, claiming genetic improvement. However, this is constrained by the lack of genetic resources for most of these crops. Here we first review the advantages of cultivating novel perennial biomass crops on MALs, highlighting management practices to enhance the environmental and economic sustainability of these agro-systems. Subsequently, we discuss the preeminent breeding targets to improve the yield and quality of the biomass obtainable from these crops, as well as the stability of biomass production under MALs conditions. These targets include crop architecture and phenology, efficiency in the use of resources, lignocellulose composition in relation to bio-based applications, and tolerance to abiotic stresses. For each target trait, we outline optimal ideotypes, discuss the available breeding resources in the context of (orphan) biomass crops, and provide meaningful examples of genetic improvement. Finally, we discuss the available tools to breed novel perennial biomass crops. These comprise conventional breeding methods (recurrent selection and hybridization), molecular techniques to dissect the genetics of complex traits, speed up selection, and perform transgenic modification (genetic mapping, QTL and GWAS analysis, marker-assisted selection, genomic selection, transformation protocols), and novel high-throughput phenotyping platforms. Furthermore, novel tools to transfer genetic knowledge from model to orphan crops (i.e., universal markers) are also conceptualized, with the belief that their development will enhance the efficiency of plant breeding in orphan biomass crops, enabling a sustainable use of MALs for biomass provision.

Raw, torrefied, and alkaline-treated biomass as a sorbent for lead in water

Two dedicated biomass crops, shrub willow (Salix sp.) and miscanthus (Miscanthus giganteus), were evaluated for their ability to remove lead from contaminated water, both in raw ground form and after pretreatment by torrefaction or alkaline treatment. Sorption capacity experiments were conducted using a contaminant concentration that ranged from 1 mg to 15 mg per L and a biomass loading rate of 0.05 g biomass per mL. The results indicated that sorption capacities for the two feedstocks ranged from 0.15 mg to 0.26 mg of lead removed per gram of biomass, and the percentage of removal ranged from 54.3% to 93.6%. The sorption capacity of willow tended to decrease as particle size increased. Increasing torrefaction severity increased the sorption capacity of miscanthus, and alkaline treatment also increased the sorption capacity of miscanthus. The Langmuir isotherm, when fitted to measured data, characterized the samples’ sorption performance with a Mean Absolute Error (MAE) of 0.0014 mmol g-1.

Carbon and evapotranspiration dynamics of a non-native perennial grass with biofuel potential in the southern U.S. Great Plains

Old world bluestem cultivar WW-B Dahl [Bothriochloa bladhii (Retz.), S. T. Blake] is a non-native perennial C4 bunch grass with biofuel production potential grown predominantly in the Southern U.S. Great Plains. Although this is a popular introduced grass cultivar, data on carbon fluxes and evapotranspiration (ET) from this warm-season grass is rare. In this study, the eddy covariance method was used to measure CO2 and ET from an established stand of bluestem for three years (2013–2015). Year 2015 had the highest gross primary production (GPP; 1358 ± 143 g C m−2) followed by 2014 (1250 ± 31 g C m−2) and 2013 (1024 ± 91 g C m−2). The average loss of GPP as ecosystem respiration (Reco) was 76%. Annual NEE sums were -302 ± 15 g C m−2 in 2013, -265 ± 41 g C m-2 in 2014, and -287 ± 32 g C m−2 in 2015. Results from this study show that the NEE in grasslands in years with normal precipitation that is well distributed may not vary from years with above-normal precipitation. This is because precipitation enhances Reco along with carbon uptake, which may result in lower net carbon uptake in perennial grasslands in higher precipitation years than normal precipitation years. Gross primary production showed a linear relationship with ET (R2 = 0.90) and above ground biomass (R2 = 0.74). Only 26% of the GPP was allocated to above ground biomass indicating a higher allocation of carbon to below ground biomass. The water use efficiency of bluestem (2.9 g C kg-1 of water) matched well with that of native prairies and other dedicated biomass crops grown in the Southern Great Plains. As the demand for cellulosic biofuels is increasing, results from field experiments quantifying seasonal changes in carbon fluxes and ET could be important in understanding the contributions of large-scale production of novel biomass crops to regional carbon and hydrologic cycles.

Nutrient and drought stress: implications for phenology and biomass quality in miscanthus.

Background and Aims The cultivation of dedicated biomass crops, including miscanthus, on marginal land provides a promising approach to the reduction of dependency on fossil fuels. However, little is known about the impact of environmental stresses often experienced on lower-grade agricultural land on cell-wall quality traits in miscanthus biomass crops. In this study, three different miscanthus genotypes were exposed to drought stress and nutrient stress, both separately and in combination, with the aim of evaluating their impact on plant growth and cell-wall properties. Methods Automated imaging facilities at the National Plant Phenomics Centre (NPPC-Aberystwyth) were used for dynamic phenotyping to identify plant responses to separate and combinatorial stresses. Harvested leaf and stem samples of the three miscanthus genotypes (Miscanthus sinensis, Miscanthus sacchariflorus and Miscanthus × giganteus) were separately subjected to saccharification assays, to measure sugar release, and cell-wall composition analyses. Key Results Phenotyping showed that the M. sacchariflorus genotype Sac-5 and particularly the M. sinensis genotype Sin-11 coped better than the M. × giganteus genotype Gig-311 with drought stress when grown in nutrient-poor compost. Sugar release by enzymatic hydrolysis, used as a biomass quality measure, was significantly affected by the different environmental conditions in a stress-, genotype- and organ-dependent manner. A combination of abundant water and low nutrients resulted in the highest sugar release from leaves, while for stems this was generally associated with the combination of drought and nutrient-rich conditions. Cell-wall composition analyses suggest that changes in fine structure of cell-wall polysaccharides, including heteroxylans and pectins, possibly in association with lignin, contribute to the observed differences in cell-wall biomass sugar release.ConclusionsThe results highlight the importance of the assessment of miscanthus biomass quality measures in addition to biomass yield determinations and the requirement for selecting suitable miscanthus genotypes for different environmental conditions.

Biomass for biofuel: Understanding the risks and opportunities for Ontario agriculture.

Markets for biomass are emerging across Canada; however, considerable concern has been expressed regarding the ability of Canada’s arable land base to sustainably meet this emerging demand. Using Ontario as a case study, economic and environmental factors that must be considered when designing biomass production systems based on either crop residues from maize (Zea mays L.), soybean [Glycine max (L.) Merr.], or winter wheat (Triticum aestivum L.) or on dedicated biomass crops such as Miscanthus (Miscanthus spp.) or switchgrass (Panicum virgatum L.) are reviewed. The Ontario agricultural land base is characterized by a growing prevalence of maize and soybean rotations, a high percentage of total arable land under the Canada Land Inventory categorized as Class 1 and 2, and geographically dispersed Class 3–5 land. Economic and environmental risks and opportunities of biomass production are demonstrated to be a function of the source of biomass, land availability, land classification, and existing land use pa...

Breeding for Biomass Yield in Switchgrass Using Surrogate Measures of Yield

Development of switchgrass (Panicum virgatum L.) as a dedicated biomass crop for conversion to energy requires substantial increases in biomass yield. Most efforts to breed for increased biomass yield are based on some form of indirect selection. The objective of this paper is to evaluate and compare the expected efficiency of several indirect measures of breeding value for improving sward-plot biomass yield of switchgrass. Sward-plot biomass yield, row-plot biomass, and spaced-plant biomass were measured on 144 half-sib families or their maternal parents from the WS4U-C2 breeding population of upland switchgrass. Heading date was also scored on row plots and anthesis date was scored on spaced plants. Use of any of these indirect selection criteria was expected to be less efficient than direct selection for biomass yield measured on sward plots, when expressed as genetic gain per year. Combining any of these indirect selection criteria with half-sib family selection for biomass yield resulted in increases in efficiency of 14 to 36%, but this could only be achieved at a very large cost of measuring phenotype on literally thousands of plants that would eventually have no chance of being selected because they were derived from inferior families. Genomic prediction methods offered the best solution to increase breeding efficiency by reducing average cycle time, increasing selection intensity, and placing selection pressure on all additive genetic variance within the population. Use of genomic selection methods is expected to double or triple genetic gains over field-based half-sib family selection.

Gametophytic Self‐Incompatibility Is Operative in Miscanthus sinensis (Poaceae) and Is Affected by Pistil Age

Miscanthus sinensis Anderss. (Poaceae) has desirable traits for a dedicated biomass crop. An important breeding goal for M. sinensis is to develop F1 hybrid cultivars. A clear understanding of its reproductive mode will help to identify effective breeding strategies toward that goal. We performed >1000 semi‐in‐vivo reciprocal crosses and self‐pollinations to determine pollen–pistil compatibility responses. Self‐pollination showed a self‐incompatibility (SI) response typical for grasses, indicating that SI is operative in M. sinensis. The majority of self‐pollen produced short tubes that terminated at the stigmatic surface of mature pistils, but some self‐pollen tubes entered into the transmitting tract. The developmental stage of pistils affects pollen–pistil interactions, as younger pistils allowed significantly more self‐pollen to enter the transmitting tract, with some even reaching the ovule. Cross pollinations among progeny of reciprocal crosses between the cultivar Gross Fontaine and the cultivar Undine showed four classes of compatibility responses with 0, 50, 75, and 100% compatible pollen and exhibited differences in reciprocal compatibility for certain crosses. Taken together, our results showed that SI in M. sinensis is gametophytic and is likely controlled by a multiallelic, two‐locus S and Z system, similar to those reported for other grasses. The findings from this study will facilitate the identification and isolation of genes related to SI and ultimately F1 hybrid production in M. sinensis.

Soil denitrifier community size changes with land use change to perennial bioenergy cropping systems

Abstract. Dedicated biomass crops are required for future bioenergy production. However, the effects of large-scale land use change (LUC) from traditional annual crops, such as corn–soybean rotations to the perennial grasses (PGs) switchgrass and miscanthus, on soil microbial community functioning is largely unknown. Specifically, ecologically significant denitrifying communities, which regulate N2O production and consumption in soils, may respond differently to LUC due to differences in carbon (C) and nitrogen (N) inputs between crop types and management systems. Our objective was to quantify bacterial denitrifying gene abundances as influenced by corn–soybean crop production compared to PG biomass production. A field trial was established in 2008 at the Elora Research Station in Ontario, Canada (n = 30), with miscanthus and switchgrass grown alongside corn–soybean rotations at different N rates (0 and 160 kg N ha−1) and biomass harvest dates within PG plots. Soil was collected on four dates from 2011 to 2012 and quantitative PCR was used to enumerate the total bacterial community (16S rRNA) and communities of bacterial denitrifiers by targeting nitrite reductase (nirS) and N2O reductase (nosZ) genes. Miscanthus produced significantly larger yields and supported larger nosZ denitrifying communities than corn–soybean rotations regardless of management, indicating large-scale LUC from corn–soybean to miscanthus may be suitable in variable Ontario climatic conditions and under varied management, while potentially mitigating soil N2O emissions. Harvesting switchgrass in the spring decreased yields in N-fertilized plots, but did not affect gene abundances. Standing miscanthus overwinter resulted in higher 16S rRNA and nirS gene copies than in fall-harvested crops. However, the size of the total (16S rRNA) and denitrifying bacterial communities changed differently over time and in response to LUC, indicating varying controls on these communities.

The impact of soil salinity on the yield, composition and physiology of the bioenergy grass Miscanthus × giganteus

AbstractHigh salinity land may provide an alternative resource for the cultivation of dedicated biomass crops for renewable energy and chemicals, thus avoiding competition for land use with food crops. The commercial perennial grass Miscanthus × giganteus is a leading biomass crop; however, its response to salt stress is largely unknown. Miscanthus × giganteus was grown in pots irrigated with nine different NaCl concentrations (0, 2.86, 5.44, 7.96, 10.65, 14.68, 17.5, 19.97 and 22.4 dS m−1). Biomass yield was reduced by 50% at 10.65 dS m−1 NaCl. Root dry matter inhibition occurred at the highest salt concentration tested, while rhizome dry weight and the ratios of root/rhizome and below‐/above‐ground dry matter were not affected by elevated salinity. The accumulative effect of increasing salinity reduced stem height and elongation, while photosynthesis was reduced to a smaller extent. The duration and strength of salinity exacerbated the reduction. Water use efficiency (WUE) was maintained except at the highest salinity and plants maintained stomatal conductance (gs) and leaf water content at low to moderate salinity. Miscanthus × giganteus showed strong induction of the osmoprotectant, proline and no significant increase in malondialdehyde content under increasing salinity. The ash content in leaves, increased, reducing the biomass quality at high salinity concentrations. The effects of salinity on the yield and the availability of land area in European geographical area for agriculture were investigated. Understanding the potential for growth of the C4 biomass crop Miscanthus on underutilized or abandoned land may offer a new range of targets for improved economics, crop management and breeding.

Economic Assessment of Producing Corn and Cellulosic Ethanol Mandate on Agricultural Producers and Consumers in the United States

Strong support for the biofuels program in the USA is expected to influence dedicated biomass crops production. Their production is expected to compete for resources with traditional crops and in turn influence commodity prices, economic surplus, and trade balance. Implications of dedicated biomass crop as bioenergy feedstock, alternative energy policies, and government initiatives on agricultural producers and consumers are evaluated using a national quantitative model, AGSIM. Economic impacts include effect on cropping patterns, crop prices, fertilizer prices, consumer and producer surplus, and trade balance. Economic analyses based on alternative assumptions related to marginal lands currently in conservation use returning to crop production as well as biomass crop yields are conducted. Results indicate that present biofuel policies are associated with large costs to consumers in terms of increased commodity prices and negative trade balance. Increase in net farm income is offset by decrease in consumer surplus. The results represent a robust set of economic impacts, which suggests policy makers to consider the unexpected economic consequences of bioenergy policy and warrants consideration of multiple alternative energy sources to achieve a sustainable energy goal.

Effect of irrigation and nitrogen fertilization on the production of biogas from maize and sorghum in a water limited environment

Abstract The expansion of biogas production from anaerobic digestion in the Po Valley (Northern Italy) has stimulated the cultivation of dedicated biomass crops, and maize in particular. A mid-term experiment was carried out from 2006 to 2010 on a silt loamy soil in Northern Italy to compare water use and energy efficiency of maize and sorghum cultivation under rain fed and well-watered treatments and at two rates of nitrogen fertilization. The present work hypothesis were: (i) biomass sorghum, for its efficient use of water and nitrogen, could be a valuable alternative to maize for biogas production; (ii) reduction of irrigation level and (iii) application of low nitrogen fertilizer rate increase the efficiency of bioenergy production. Water treatments, a rain fed control (I0) and two irrigation levels (I1 and I2; only one in 2006 and 2009), were compared in a split–split plot design with four replicates. Two fertilizer rates were also tested: low (N1, 60 kg ha−1 of nitrogen; 0 kg ha−1 of nitrogen in 2010) and high (N2, 120 kg ha−1 of nitrogen; 100 kg ha−1 of nitrogen in 2010). Across treatments, sorghum produced more aboveground biomass than maize, respectively 21.6 Mg ha−1 and 16.8 Mg ha−1 (p

Dedicated biomass crops can enhance biodiversity in the arable landscape.

Suggestions that novel, non‐food, dedicated biomass crops used to produce bioenergy may provide opportunities to diversify and reinstate biodiversity in intensively managed farmland have not yet been fully tested at the landscape scale. Using two of the largest, currently available landscape‐scale biodiversity data sets from arable and biomass bioenergy crops, we take a taxonomic and functional trait approach to quantify and contrast the consequences for biodiversity indicators of adopting dedicated biomass crops on land previously cultivated under annual, rotational arable cropping. The abundance and community compositions of biodiversity indicators in fields of break and cereal crops changed when planted with the dedicated biomass crops, miscanthus and short rotation coppiced (SRC) willow. Weed biomass was consistently greater in the two dedicated biomass crops than in cereals, and invertebrate abundance was similarly consistently higher than in break crops. Using canonical variates analysis, we identified distinct plant and invertebrate taxa and trait‐based communities in miscanthus and SRC willows, whereas break and cereal crops tended to form a single, composite community. Seedbanks were shown to reflect the longer term effects of crop management. Our study suggests that miscanthus and SRC willows, and the management associated with perennial cropping, would support significant amounts of biodiversity when compared with annual arable crops. We recommend the strategic planting of these perennial, dedicated biomass crops in arable farmland to increase landscape heterogeneity and enhance ecosystem function, and simultaneously work towards striking a balance between energy and food security.

Simulated impact of the renewable fuels standard on US Conservation Reserve Program enrollment and conversion

AbstractA socioeconomic model is used to estimate the land‐use implications on the U.S. Conservation Reserve Program from potential increases in second‐generation biofuel production. A baseline scenario with no second‐generation biofuel production is compared to a scenario where the Renewable Fuels Standard (RFS2) volumes are met by 2022. We allow for the possibility of converting expiring CRP lands to alternative uses such as conventional crops, dedicated second‐generation biofuel crops, or harvesting existing CRP grasses for biomass. Results indicate that RFS2 volumes (RFS2‐v) can be met primarily with crop residues (78% of feedstock demand) and woody residues (19% of feedstock demand) compared with dedicated biomass (3% of feedstock demand), with only minimal conversion of cropland (0.27 million hectares, <1% of total cropland), pastureland (0.28 million hectares of pastureland, <1% of total pastureland), and CRP lands (0.29 million hectares of CRP lands, 3% of existing CRP lands) to biomass production. Meeting RFS2 volumes would reduce CRP re‐enrollment by 0.19 million hectares, or 4%, below the baseline scenario where RFS2 is not met. Yet under RFS2‐v scenario, expiring CRP lands are more likely to be converted to or maintain perennial cover, with 1.78 million hectares of CRP lands converting to hay production, and 0.29 million hectares being harvested for existing grasses. A small amount of CRP is harvested for existing biomass, but no conversion of CRP to dedicated biomass crops, such as switchgrass, are projected to occur. Although less land is enrolled in CRP under RFS2‐v scenario, total land in perennial cover increases by 0.15 million hectares, or 2%, under RFS2‐v. Sensitivity to yield, payment and residue retention assumptions are evaluated.

Spatial land use trade-offs for maintenance of biodiversity, biofuel, and agriculture

Context Expansion of bioenergy production is part of a global effort to reduce greenhouse gas emissions and mitigate climate change. Dedicated biomass crops will compete with other land uses as most high quality arable land is already used for agriculture, urban development, and biodiversity conservation.

Structural characterization of (1→2)-β-xylose-(1→3)-α-arabinose-containing oligosaccharide products of extracted switchgrass (Panicum virgatum, L.) xylan after exhaustive enzymatic treatment with α-arabinofuranosidase and β-endo-xylanase

Switchgrass (Panicum virgatum, L.) is a potential dedicated biomass crop for use in biocatalytic conversion systems to biofuels. Nearly 30% of switchgrass cell wall material is xylan. The complete depolymerization of xylan is desirable both as an additional carbon source for microbial fermentation and to reduce inhibitory effects xylooligomers may have on cellulolytic glycoside hydrolase enzymes. To identify structural features of switchgrass xylan that are not distinguishable by mass spectrometry alone, a α-arabinofuranosidase enzyme was used to remove the arabinose side chains from alkali-extracted switchgrass xylan from three cultivars with simultaneous hydrolysis by β-endo-xylanase to enrich for oligosaccharide products with extended branching. The two most abundant enzymatic digestion products were separated and characterized by LC–MSn, linkage analysis, and NMR. These two oligosaccharides were present in all three switchgrass cultivars and found to contain (1→2)-β-xylose-(1→3)-α-arabinose side chains, a linkage not previously reported in switchgrass.

Brachypodium sylvaticum, a model for perennial grasses: transformation and inbred line development.

Perennial species offer significant advantages as crops including reduced soil erosion, lower energy inputs after the first year, deeper root systems that access more soil moisture, and decreased fertilizer inputs due to the remobilization of nutrients at the end of the growing season. These advantages are particularly relevant for emerging biomass crops and it is projected that perennial grasses will be among the most important dedicated biomass crops. The advantages offered by perennial crops could also prove favorable for incorporation into annual grain crops like wheat, rice, sorghum and barley, especially under the dryer and more variable climate conditions projected for many grain-producing regions. Thus, it would be useful to have a perennial model system to test biotechnological approaches to crop improvement and for fundamental research. The perennial grass Brachypodium sylvaticum is a candidate for such a model because it is diploid, has a small genome, is self-fertile, has a modest stature, and short generation time. Its close relationship to the annual model Brachypodium distachyon will facilitate comparative studies and allow researchers to leverage the resources developed for B . distachyon . Here we report on the development of two keystone resources that are essential for a model plant: high-efficiency transformation and inbred lines. Using Agrobacterium tumefaciens-mediated transformation we achieved an average transformation efficiency of 67%. We also surveyed the genetic diversity of 19 accessions from the National Plant Germplasm System using SSR markers and created 15 inbred lines.

Identification of cold-responsive genes in energycane for their use in genetic diversity analysis and future functional marker development

Breeding for cold tolerance in sugarcane will allow its cultivation as a dedicated biomass crop in cold environments. Development of functional markers to facilitate marker-assisted breeding requires identification of cold stress tolerance genes. Using suppression subtractive hybridization, 465 cold-responsive genes were isolated from the cold-tolerant energycane Ho02-144. Predicted gene interactions network indicated several associated pathways that may coordinately regulate cold tolerance responses in energycane. Expression analysis of a select set of genes, representing signaling and transcription factors, genes involved in polyamine and antioxidant biosynthesis, protein degradation and in the repair of damaged proteins in the cytosol, showed their time-dependent regulation under cold-stress. Comparative expression profiles of these genes between Ho02-144 and a cold-sensitive clone (L79-1002) showed that almost all genes were induced immediately upon imposition of cold stress and maintained their expression in Ho02-144 whereas they were either downregulated or their upregulation was very low in L79-1002. Simple sequence repeat markers derived from 260 cold-responsive genes showed allelic diversity among the cold-sensitive commercial hybrids that were distinct from the Saccharum spontaneum clones. Future efforts will target sequence polymorphism information of these genes in our ongoing QTL and association mapping studies to identify functional markers associated with cold tolerance in sugar/energycane.