Miscanthus Genotypes Research Articles

Organic Acid-Based Hemicellulose Fractionation and Cellulosic Ethanol Potential of Five Miscanthus Genotypes

The pretreatment of lignocellulosic biomass such as Miscanthus grown on marginal agricultural land is very challenging and requires severe conditions to fractionate cell wall polymers for further valorization. The current study aimed to determine organic acid-based mild conditions to pretreat contrasting lignocellulosic Miscanthus genotypes for the efficient fractionation of cell wall components, with special focus on hemicellulose extraction. In doing so, five Miscanthus genotypes were subjected to four different acid treatments (sulfuric acid, oxalic acid, malonic acid, and citric acid) in a vertical high-pressure steam sterilizer. The results demonstrated that, among the organic acids, oxalic acid was identified as the most effective pretreatment solvent for hemicellulose separation, whereas citric acid yielded the highest amount of galacturonic acid, varying from 15 to 17 mg mL−1 across genotypes. One best performing genotype was selected for the enzymatic hydrolysis. Overall, M. floridulus genotypes exhibited the optimal quality traits for efficient bioconversion with second best in terms of ethanol production potential.

Early impacts of marginal land‐use transition to Miscanthus on soil quality and soil carbon storage across Europe

AbstractMiscanthus, a C4 perennial rhizomatous grass, is a low‐input energy crop suitable for marginal land, which cultivation can improve soil quality and promote soil organic carbon (SOC) sequestration. In this study, four promising Miscanthus hybrids were chosen to evaluate their short‐term potential, in six European marginal sites, to sequester SOC and improve physical, chemical, and biological soil quality in topsoil. Overall, no differences among Miscanthus hybrids were detected in terms of impacts on soil quality and SOC sequestration. SOC sequestration rate after 4 years was of +0.4 Mg C ha−1 year−1, but land‐use transition from former cropland or grassland showed contrasting SOC sequestration trajectories. In unfertilized marginal lands, cultivation of high‐yielding Miscanthus genotypes caused a depletion of K (−216 kg ha−1 year−1), followed by Ca (−56 kg ha−1 year−1), Mg (−102 kg ha−1 year−1) and to a lesser extent of N. On the contrary, the biological turnover of organic matter increased the available P content (+164 kg P2O5 ha−1 year−1). SOC content was identified as the main driver of changes in biological soil quality. High input of labile plant C stimulated an increment of microbial biomass and enzymatic activity. Here, a novel approach was applied to estimate C input to soil from different Miscanthus organs. Despite the high estimated plant C input to soil (0.98 Mg C ha−1 year−1), with significant differences among sites and Miscanthus hybrids, it was not identified as a driver of SOC sequestration. On the contrary, initial SOC and nutrients (N, P) content, as well as their elemental stoichiometric ratios with C, were the key factors controlling SOC dynamics. Introducing Miscanthus on marginal lands impacts positively soil biological quality over the short term, but targeted fertilization plans are needed to secure crop yield over the long term as well as the C sink capacity of this perennial cropping system.

Variability of cell wall recalcitrance and composition in genotypes of Miscanthus from different genetic groups and geographical origin.

Miscanthus is a promising crop for bioenergy and biorefining in Europe. The improvement of Miscanthus as a crop relies on the creation of new varieties through the hybridization of germplasm collected in the wild with genetic variation and suitable characteristics in terms of resilience, yield and quality of the biomass. Local adaptation has likely shaped genetic variation for these characteristics and is therefore important to quantify. A key biomass quality parameter for biorefining is the ease of conversion of cell wall polysaccharides to monomeric sugars. Thus far, the variability of cell wall related traits in Miscanthus has mostly been explored in accessions from limited genetic backgrounds. Here we analysed the soil and climatic conditions of the original collection sites of 592 Miscanthus genotypes, which form eight distinct genetic groups based on discriminant analysis of principal components of 25,014 single-nucleotide polymorphisms. Our results show that species of the genus Miscanthus grow naturally across a range of soil and climate conditions. Based on a detailed analysis of 49 representative genotypes, we report generally minor differences in cell wall characteristics between different genetic groups and high levels of genetic variation within groups, with less investigated species like M. floridulus showing lower recalcitrance compared to the other genetic groups. The results emphasize that both inter- and intra- specific variation in cell wall characteristics and biomass recalcitrance can be used effectively in Miscanthus breeding programmes, while also reinforcing the importance of considering biomass yield when quantifying overall conversion efficiency. Thus, in addition to reflecting the complexity of the interactions between compositional and structural cell wall features and cell wall recalcitrance to sugar release, our results point to traits that could potentially require attention in breeding programmes targeted at improving the Miscanthus biomass crop.

Seed Germination of Two Hybrids Obtained via Cross-Pollination between Miscanthus sinensis × Miscanthus sacchariflorus

To date, economically and energy-costly vegetative propagation using rhizomes and tissue culture are the only options for the cultivation of Miscanthus spp. Some genotypes of miscanthus produce fertile seeds, offering a valid alternative to vegetative propagation. A preliminary study has been conducted on the seeds of two hybrids of miscanthus obtained via interspecific cross-pollination between M. sacchariflorus and M. sinensis: ‘GRC14’ (maternal: M. sacchariflorus) and ‘GRC10B’ (maternal: M. sinensis). Seeds were assessed for germination traits in a laboratory (at 25 °C in the dark) just after panicle harvest, and during 1-year storage at room temperature or at 8 °C. In a second experiment, the effects of gibberellic acid (GA3) solution at different concentrations (0, 50, 100, 300, 500 ppm) on the germination of freshly matured seeds were assessed. Poor germination just after harvest (<30%) indicates the occurrence of a physiological dormancy. Indeed, two months later, germination rose up to 76.7% in ‘GRC14’ and 50.8%, in ‘GRC10B’, and peaked at 95.6% in ‘GRC14’ and at 78% in ‘GRC10B’, 6 months after harvest. After a total of 12 months, germination was significantly reduced in both hybrids (≈60%). Seeds stored at room temperature lost dormancy earlier than those stored at 8 °C. Overall, germination was significantly improved by GA3, but the extent of the GA effect was genotype-dependent. In conclusion, a low establishment rate may result from direct seeding when fresh seed is used in the field. In this case, the use of GA3 is a possible strategy to ameliorate the impact of dormancy on seed germination. In the case of delayed sowings in late winter–early spring, seeds stored at room temperature after harvest may better perform than those stored at 8 °C.

Deep Convolutional Neural Networks Exploit High-Spatial- and -Temporal-Resolution Aerial Imagery to Phenotype Key Traits in Miscanthus

Miscanthus is one of the most promising perennial crops for bioenergy production, with high yield potential and a low environmental footprint. The increasing interest in this crop requires accelerated selection and the development of new screening techniques. New analytical methods that are more accurate and less labor-intensive are needed to better characterize the effects of genetics and the environment on key traits under field conditions. We used persistent multispectral and photogrammetric UAV time-series imagery collected 10 times over the season, together with ground-truth data for thousands of Miscanthus genotypes, to determine the flowering time, culm length, and biomass yield traits. We compared the performance of convolutional neural network (CNN) architectures that used image data from single dates (2D-spatial) versus the integration of multiple dates by 3D-spatiotemporal architectures. The ability of UAV-based remote sensing to rapidly and non-destructively assess large-scale genetic variation in flowering time, height, and biomass production was improved through the use of 3D-spatiotemporal CNN architectures versus 2D-spatial CNN architectures. The performance gains of the best 3D-spatiotemporal analyses compared to the best 2D-spatial architectures manifested in up to 23% improvements in R2, 17% reductions in RMSE, and 20% reductions in MAE. The integration of photogrammetric and spectral features with 3D architectures was crucial to the improved assessment of all traits. In conclusion, our findings demonstrate that the integration of high-spatiotemporal-resolution UAV imagery with 3D-CNNs enables more accurate monitoring of the dynamics of key phenological and yield-related crop traits. This is especially valuable in highly productive, perennial grass crops such as Miscanthus, where in-field phenotyping is especially challenging and traditionally limits the rate of crop improvement through breeding.

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.

PERSPECTIVES FOR THE USE OF BIOMASS GENERATED BY SOME MISCANTHUS GENOTYPES IN THE PRODUCTION OF DENSIFIED SOLID BIOFUELS

Miscanthus is a Poaceae family perennial crop of C4 bioenergy characterized by the multilateral use potential, including the production of biofuels. The paper aimed to study the opportunity to use the biomass generated by two Miscanthus genotypes: Miscanthus × giganteus and Miscanthus sinensis in the production of densified solid biofuels. We quantified the biomass generated by crops that were 5 years old, harvested from both genotypes after the vegetation period, the year 2020. Samples were taken from the experimental lots of the Alexandru Ciubotaru National Botanical Garden (Institute) from the Republic of Moldova in autumn, immediately after the initial onset of senescence and in spring of the following year, before the start of the growing season. The results showed that the above-ground biomass generated by both Miscanthus genotypes harvested in spring had had significantly higher quality characteristics compared to the biomass harvested in autumn. Virtually all qualitative indices of the Miscanthus × giganteus biomass harvested in spring comply with the requirements of the ENPlus international standards for densified solid biofuels. The Miscanthus sinensis biomass, both, had lower indices than the Miscanthus × giganteus biomass from both qualitative and quantitative points of view and the former can be used as a filler in various mixtures of raw material for the production of solid biofuels.

Physiological response of Miscanthus genotypes to salinity stress under elevated CO2

AbstractMiscanthus is a class of C4 perennial grasses, which can be cultivated on marginal land even with high salinity. However, the future environment may be altered by elevated atmospheric CO2 concentration ([CO2]) and knowledge is limited about the interactive impacts of CO2 enrichment and salinity on this C4 bioenergy crop. In this study, three Miscanthus genotypes (M. sacchariflorus, M. × giganteus, and M. lutarioriparius) were grown under either ambient (400 ppm) [CO2] (a[CO2]) or elevated (800 ppm) [CO2] (e[CO2]) at five salinity levels (0, 50, 100, 150, and 200 mm NaCl denoted as S0, S1, S2, S3, and S4, respectively), and the impacts of e[CO2] on plant physiological responses to salt stress were investigated. Our results suggested that e[CO2] had no obvious effect on net photosynthetic rate (An), but significantly reduced the stomatal conductance (gs), thus improving water use efficiency regardless of salinity levels. In addition, e[CO2] could improve water potential of plants under both control and saline conditions, but the magnitude of increase was highly genotypic dependent. The maximum quantum yield of photosystem II (Fv/Fm) was not altered by e[CO2], which, however, could alleviate the negative effect of salt on Fv/Fm. Furthermore, salt stress increased the concentration of abscisic acid (ABA) in xylem sap and leaves, while the effect of e[CO2] on ABA level was closely associated with genotypes. e[CO2] reduced Na+ concentration and had positive influences on maintaining Na+/K+ ratio, thus favoring ionic homeostasis, although such effect was genotype dependent. Collectively, our data suggested that e[CO2] could partially mitigate the detrimental effects of salinity, conferring higher salt tolerance of Miscanthus.

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

AbstractMiscanthus 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.

Hodnotenie vybraných genotypov Miscanthus na produkciu bioplynu ako možného riešenia regionálnej bioenergie

Plantations of fast-growing crops represent local agroecosystems providing provisioning services in the form of phytomass that can be utilized for energy and/or non-energy purposes. Permanent grasses such as Miscanthus are identified as potentially suitable sources of raw materials for the output of second-generation biofuels. The experiments focused on the production ability of the perennial energy grass Miscanthus were performed in the region of SW Slovakia. It was confirmed that the studied genotypes (Miscanthus sinensis Tatai and Miscanthus × giganteus) exceeded the cost-efficient level of biomass production. The above-ground biomass of the studied genotypes was ensiled and afterwards fed to the experimental fermenters to evaluate the biogas production. The experiments with individual silage mixtures lasted 600 hours. The total amount of biogas produced from M. × giganteus and M. sinensis Tatai silage mixture was 273 dm3 and 328 dm3, respectively. The average share of methane in the biogas of both studied samples of silage mixtures was 51%. On the basis of the 10-year average yields of the studied Miscanthus genotypes achieved in our conditions, it is possible to produce 8 181 m3/ha (M. × giganteus) and 11 248 m3/ha (M. sinensis Tatai) of biogas from the silage mixtures. The achieved production represents sufficient and stable amount of biogas and its use can be economically efficient and sustainable in the long run in SW Slovakia.

Assessment of Drought Tolerance of Miscanthus Genotypes through Dry-Down Treatment and Fixed-Soil-Moisture-Content Techniques

Miscanthus, a high-yielding, warm-season C4 grass, shows promise as a potential bioenergy crop in temperate regions. However, drought may restrain productivity of most genotypes. In this study, total 29 Miscanthus genotypes of East-Asian origin were screened for drought tolerance with two methods, a dry-down treatment in two locations and a system where soil moisture content (SMC) was maintained at fixed levels using an automatic irrigation system in one location. One genotype, Miscanthus sinensis PMS-285, showed relatively high drought-tolerance capacity under moderate drought stress. Miscanthus sinensis PMS-285, aligned with the M. sinensis ‘Yangtze-Qinling’ genetic cluster, had relatively high principal component analysis ranking values in both two locations experiments, Hokkaido University and Brigham Young University. Genotypes derived from the ‘Yangtze-Qinling’ genetic cluster showed relatively greater photosynthetic performance than other genetic clusters, suggesting germplasm from this group could be a potential source of drought-tolerant plant material. Diploid genotypes showed stronger drought tolerance than tetraploid genotypes, suggesting ploidy could be an influential factor for this trait. Of the two methods, the dry-down treatment appears more suitable for selecting drought-tolerant genotypes given that it reflects water-stress conditions in the field. However, the fixed-SMC experiment may be good for understanding the physiological responses of plants to relatively constant water-stress levels.

Prospects and methods of polyploid selection of new high-yielding miscanthus clones in the natural climatic conditions of Ukraine

Goal. Expanding the breeding trait collection of breeding genotypes of the genus Miscanthus (Anderson) and the genetic basis for new allotriploid clones by transferring components for hybridization of natural wild species Miscanthus sinensis and Miscanthus sacchariflorus to the tetraploid level.
 Methods. Cytological, biotechnological, fluorescent cytphotometry, field, laboratory.
 Results. The efficiency of polyploidisation for induction of new tetraploid forms of miscanthus in liquid nutrient media supplemented with colchicine (0.05% mass) and for stabilization of myxoploid shoots (0.005% mass) for 6 h of cultivation is examined. The period of exposure for Miscanthus sinensis (2x=2x= 38) and Miscanthus sacchariflorus (2x = 2x = 38) varied from 2 hours to 3 days depending on the genetic origin of the material, with transfer to a hormonal environment. The best indicators of tetraploid induction for Miscanthus sinensis were observed for the exposure period of 2 days with polyploidization efficiency (Db%) of 31.25% and 21.42%, and for Miscanthus sacchariflorus 2 and 6 hours with 35.0% and 27.3%, respectively. The technology of transfering rooted shoots into the soil on the Yaltushkiv Eperimental Breeding Farm was improved and the composition of the soil mixture that provided 99% rooting of culture seedlings at a humidity of 60−70% and air temperature of 35−55°С was found.
 Conclusions. New biotechnological tetraploid lines of Miscanthus sinensis (2xn=4x=76) and Miscanthus sacchariflorus (2xn=4x=76) were created in the conditions of liquid nutrient media supplemented with colchicine (0.05 % mass). It is investigated that flowering of new tetraploid clones in the conditions of Ukraine for the second year of vegetation occurs from late September to early October with formation of fertile pollen grains.

Influence of cutting height on biomass yield and quality of miscanthus genotypes

AbstractCommercially achieved biomass yields are often lower than those obtained in scientific plot trials and estimated by crop models. This phenomenon is commonly referred to as the ‘commercial yield gap’. It needs to be understood and managed to achieve the yield expectations that underpin business models. Cutting height at harvest is one of the key factors determining biomass yield and quality. This study quantifies the impacts of cutting heights of diverse genotypes with different morphologies and in years with contrasting weather conditions before and during harvest. Harvests were made in March 2015 and March 2018 of six diverse miscanthus genotypes planted as part of the ‘OPTIMISC project’ in 2013 near Stuttgart, Germany. Biomass yield, dry matter content and nutrient concentrations were analysed in four 10 cm fractions working upwards from the ground level and a fifth fraction with the shoot biomass higher than 40 cm. As stems are slightly tapered (i.e. diameter decreases slightly with increasing cutting height), it was hypothesized that low cutting may lead to yield gains, but that these may be associated with lower quality biomass with higher moisture and higher nutrient offtakes. We calculated average yield losses of 270 kg ha−1 (0.83%) with each 1 cm increase in cutting height up to 40 cm. Although whole shoot mineral concentrations were significantly influenced by both genotype and year interactions, total nitrogen (1.89 mg g−1), phosphorus (0.51 mg g−1), potassium (3.72 mg g−1) and calcium (0.89 mg g−1) concentrations did not differ significantly from the concentrations in the lower basal sections. Overall, cutting height had a limited influence on nutrient and moisture content. Therefore, we recommend that cutting is performed as low as is practically possible with the available machinery and local ground surface conditions to maximize biomass yield.

Variability of stem solidness among miscanthus genotypes and its role on mechanical properties of polypropylene composites

AbstractMiscanthus (Miscanthus Andersson) is a perennial grass that is attracting growing interest from the biomaterial industry. Our aim was to compare miscanthus genotypes varying in stem solidness, a measure of degree to which pith fills cavity between the outer walls of the stem, and analyze whether this trait influences the mechanical properties of polypropylene composites reinforced with miscanthus particles. Six contrasting genotypes were chosen from a Miscanthus sinensis population to determine morphological variables, stem solidness, and mechanical properties of polypropylene composites including 30% of milled miscanthus particles of two sizes of 100 < × < 200 μm and 200 < × < 300 μm. Although aboveground biomass of miscanthus was closely related to the aboveground volume of the plant, namely stand volume, a few genotypes showed contrasting aboveground biomass production for similar stand volumes. This generated contrasting ratio between aboveground biomass and stand volume, namely plant‐specific weights, for similar plant volumes. A principal component analysis showed that fully pith‐filled stems, namely solid stems, were explained by a large stand volume and plant‐specific weights as well as small stem cross‐sections. Genotypes showing partially filled stems were taller with larger stem cross‐sections but smaller plant‐specific weights. They revealed high lignin and p‐coumaric acid contents. Compared to neat‐polypropylene, Young's modulus increased significantly by 139% and 134% and tensile strength by 39% and 36% for genotypes with partially filled stems compared to genotypes with fully pith‐filled stems, respectively. This difference in reinforcing capacity was similar to that of two particle sizes (139% and 134% for Young's modulus, 41% and 34% for tensile strength, respectively). A good tensile strength was obtained with large cross‐stem section, plant height and lignin and p‐coumaric acid contents. It decreased with plant‐specific weight, hemicellulose and ferulic acid contents. Wider morphological variations in other progenies or Miscanthus species should be explored further using the techniques reported here.

Quantitative assessment of the potential for soil improvement by planting Miscanthus on saline‐alkaline soil and the underlying microbial mechanism

AbstractPhytoremediation using Miscanthus is a valuable technique for the restoration of saline‐alkaline soil, but the potential is not quantified. To assess this potential, a 5 years field experiment was conducted on saline‐alkaline soils with three genotypes of Miscanthus and an unplanted control. The bulk soil (0–20‐cm depth) physicochemical properties were measured annually from 2015 to 2018, while the bacterial and fungal community structures of the rhizosphere soil were investigated by high‐throughput sequencing after 5 years under Miscanthus (2018). The results showed that Miscanthus cultivation on saline‐alkaline soil reduced soil salinization and improved soil fertility on this site. Specifically, compared with the blank control, the five‐years Miscanthus cultivation (mean of three different genotypes pooled) decreased the soil pH by 0.33 units (8.78–8.45) and electrical conductivity by 23.4 μS/cm (226.7–203.3 μS/cm), as well as increasing soil organic matter content from 18.9 to 34.9 g/kg and total potassium content from 15.2 to 18.0 g/kg. In addition, the soil improvement was more pronounced with a longer duration of growth. Miscanthus remediates saline‐alkaline soils by altering the microbial community compositional abundance rather than its diversity. The improvement is due to enrichment of beneficial bacteria leading to soil desalinization (e.g., by Gemmatimonadaceae), litter decomposition (e.g., by Chitinophagaceae), plant growth promotion (e.g., by Micrococcaceae), and the reduction of harmful fungi (e.g., Pleosporales and Chitinophagaceae). Soil pH, electrical conductivity, organic matter, and total potassium were the main physicochemical properties affecting bacterial and fungal communities. Our results quantify the soil improvement potential of Miscanthus and clarify the underlying microbial mechanisms, laying a solid foundation for further implementation of saline‐alkaline soil phytoremediation using Miscanthus. In the future, more extensive multi‐location trials are required to assess if these improvements are seen across a wide diversity of environments.

Physiological and transcriptional response to drought stress among bioenergy grass Miscanthus species

BackgroundMiscanthus is a commercial lignocellulosic biomass crop owing to its high biomass productivity, resilience and photosynthetic capacity at low temperature. These qualities make Miscanthus a particularly good candidate for temperate marginal land, where yields can be limited by insufficient or excessive water supply. Differences in response to water stress have been observed among Miscanthus species, which correlated to origin. In this study, we compared the physiological and molecular responses among Miscanthus species under excessive (flooded) and insufficient (drought) water supply in glasshouse conditions.ResultsA significant biomass loss was observed under drought conditions in all genotypes. M. x giganteus showed a lower reduction in biomass yield under drought conditions compared to the control than the other species. Under flooded conditions, biomass yield was as good as or better than control conditions in all species. 4389 of the 67,789 genes (6.4%) in the reference genome were differentially expressed during drought among four Miscanthus genotypes from different species. We observed the same biological processes were regulated across Miscanthus species during drought stress despite the DEGs being not similar. Upregulated differentially expressed genes were significantly involved in sucrose and starch metabolism, redox, and water and glycerol homeostasis and channel activity. Multiple copies of the starch metabolic enzymes BAM and waxy GBSS-I were strongly up-regulated in drought stress in all Miscanthus genotypes, and 12 aquaporins (PIP1, PIP2 and NIP2) were also up-regulated in drought stress across genotypes.ConclusionsDifferent phenotypic responses were observed during drought stress among Miscanthus genotypes from different species, supporting differences in genetic adaption. The low number of DEGs and higher biomass yield in flooded conditions supported Miscanthus use in flooded land. The molecular processes regulated during drought were shared among Miscanthus species and consistent with functional categories known to be critical during drought stress in model organisms. However, differences in the regulated genes, likely associated with ploidy and heterosis, highlighted the value of exploring its diversity for breeding.

Managing flowering time in Miscanthus and sugarcane to facilitate intra- and intergeneric crosses.

Miscanthus is a close relative of Saccharum and a potentially valuable genetic resource for improving sugarcane. Differences in flowering time within and between Miscanthus and Saccharum hinders intra- and interspecific hybridizations. A series of greenhouse experiments were conducted over three years to determine how to synchronize flowering time of Saccharum and Miscanthus genotypes. We found that day length was an important factor influencing when Miscanthus and Saccharum flowered. Sugarcane could be induced to flower in a central Illinois greenhouse using supplemental lighting to reduce the rate at which days shortened during the autumn and winter to 1 min d-1, which allowed us to synchronize the flowering of some sugarcane genotypes with Miscanthus genotypes primarily from low latitudes. In a complementary growth chamber experiment, we evaluated 33 Miscanthus genotypes, including 28 M. sinensis, 2 M. floridulus, and 3 M. ×giganteus collected from 20.9° S to 44.9° N for response to three day lengths (10 h, 12.5 h, and 15 h). High latitude-adapted M. sinensis flowered mainly under 15 h days, but unexpectedly, short days resulted in short, stocky plants that did not flower; in some cases, flag leaves developed under short days but heading did not occur. In contrast, for M. sinensis and M. floridulus from low latitudes, shorter day lengths typically resulted in earlier flowering, and for some low latitude genotypes, 15 h days resulted in no flowering. However, the highest ratio of reproductive shoots to total number of culms was typically observed for 12.5 h or 15 h days. Latitude of origin was significantly associated with culm length, and the shorter the days, the stronger the relationship. Nearly all entries achieved maximal culm length under the 15 h treatment, but the nearer to the equator an accession originated, the less of a difference in culm length between the short-day treatments and the 15 h day treatment. Under short days, short culms for high-latitude accessions was achieved by different physiological mechanisms for M. sinensis genetic groups from the mainland in comparison to those from Japan; for mainland accessions, the mechanism was reduced internode length, whereas for Japanese accessions the phyllochron under short days was greater than under long days. Thus, for M. sinensis, short days typically hastened floral induction, consistent with the expectations for a facultative short-day plant. However, for high latitude accessions of M. sinensis, days less than 12.5 h also signaled that plants should prepare for winter by producing many short culms with limited elongation and development; moreover, this response was also epistatic to flowering. Thus, to flower M. sinensis that originates from high latitudes synchronously with sugarcane, the former needs day lengths >12.5 h (perhaps as high as 15 h), whereas that the latter needs day lengths <12.5 h.

Thermal and dynamic mechanical characterization of miscanthus stem fragments: Effects of genotypes, positions along the stem and their relation with biochemical and structural characteristics

The thermal and dynamic mechanical properties of miscanthus stem fragments and differences between genotypes and positions along the stem are studied in relation with their biochemical and structural characteristics. The starting degradation temperature does not correlate to the biochemical composition. However, the first DTG peak temperature is negatively correlated to hemicelluloses content and positively correlated to lignin and p-coumaric contents. A pronounced genotypic effect is evidenced on fragments elastic moduli while limited effect of the position along the stem is found. This is mostly related to ferulic and p-coumaric acid contents of stem fragments for which a strong correlation to elastic moduli is evidenced. Our results highlight that genotypic effect, position along the stem, stem fragment dimensions and mechanical properties of miscanthus stem fragments are strongly interconnected in relation with their respective biochemical and structural characteristics. This opens interesting perspectives for identifying key biological traits that need to be optimized for a better selection of performing miscanthus genotypes targeted to polymer composite applications.

Wild Miscanthus Germplasm in a Drought-Affected Area: Physiology and Agronomy Appraisals

Predictions of future climate scenarios indicate that yields from perennial biomass crops (PBCs) growing in the Mediterranean region are likely to decline due to prolonged drought. Among PBCs, Miscanthus grasses with C4 photosynthesis combine high yield potentials and water use efficiencies. However, the standard commercial clone M. x giganteus (Mxg), with minimal stomatal regulation, is too sensitive to drought for reliable yields in the Mediterranean regions. This paper screened a diverse panel of thirteen Miscanthus genotypes (M. sinensis, M. floridulus, M. sacchariflorus and Mxg) to identify which types could maximize yield under summer drought conditions typical in the South Mediterranean climate. In the second growing season, significant differences were observed for plant height (from 63 to 185 cm), stem number (from 12 to 208 stems plant−1), biomass yield (from 0.17 to 6.4 kg DM plant−1) and whole crop water use efficiency (from 0.11 to 7.0 g L−1). Temporal variation in net photosynthesis, stomatal conductance, transpiration rate and instantaneous water use efficiency identified different strategies adopted by genotypes, and that genotypes selected from M. floridulus and M. sinensis were better adapted to rainfed conditions and could produce six times more biomass than the Mxg. These accessions are being used as parents in experimental breeding aimed at producing future seed-based drought resilient hybrids.

Sterilization procedures and Plant Preservative Mixture on in vitro establishment of Miscanthus sinensis Andersson

Information about the establishment phase of Miscanthus sinensis as sterile procedure to avoid the contamination were few reported. The aim of this study was to evaluate different immersion sterilization procedures with and without the biocide, Plant Preserve Mixture™ (PPM™) on in vitro contamination of two Miscanthus genotypes. The plant material, canes from PI 668371 and PI 668375 accessions come from adult plants cultivated in the germplasm bank of USDA-ARS, Griffin, Georgia. Apical meristems were submitted to an immersion sterilization procedures (70% isopropyl alcohol and 1.5, 5.0 or 8.25% NaOCl for different time periods, followed by rinsing three times with autoclaved distilled water. After that, the explants were inoculated on MS basal medium in the presence or absence of 1 mL L-1 PPM™. The experimental design was fully randomized in a 2 x 5 x 2 factorial scheme (genotypes x sterilization process x PPM™) with five repetitions per treatment and five apical meristems per experimental unit. The highest level of bacterial contamination (100%) and lowest explant survival (0%) were recorded in medium without PPM™. For fungal contamination, the biocide was effective only in reducing contamination for PI 668375 due to its higher potential for fungal contamination. For both percentage of fungal and bacterial contamination, the PPM™ biocide can be an efficient agent to prevent contamination in vitro Miscanthus sp. cultures. Aseptic treatments not showed differences for percentage of bacterial and fungal contaminations and percentage of explant survival. Index terms: Micropropagation; in vitro contamination; Saccharum complex.