Do Miscanthus lutarioriparius-Based Oriented Strand Boards Provide Environmentally Benign Alternatives? An LCA Case Study of Lake Dongting District in China

Miscanthus lutarioriparius(M. lutarioriparius) in Lake Dongting District are in the situation of being discarded due to the government’s environmental policy, the decomposition of which will bring another pollution risk. The purpose of this study is to environmentally analyze the production of M. lutarioriparius-based oriented strand particleboards(M.OSB) as alternatives to the conventional artificial boards. The production systems were evaluated from a cradle-to-gate perspective using the Life Cycle Assessment(LCA)methodology. Our results showed that the M.OSB had an overall better profile than wood panels, identifying the production of starch adhesives and bio-fuels as the main environmental hotspots. It was also found that annual harvesting and utilization of M. lutarioripariuscould ease the burden to the environment during the decomposition of this plant, and further improve the environmental performance of M.OSB. Sensitivity analyses were conducted on the key parameters, suggesting that there are opportunities for improvement. This study provides useful information for enterprises and policymakers on where to focus their activities, with the aim of making the future of M. lutarioriparius utilization more technically and environmentally favourable.

Chromosome-scale assembly and analysis of biomass crop Miscanthus lutarioriparius genome

Miscanthus, a rhizomatous perennial plant, has great potential for bioenergy production for its high biomass and stress tolerance. We report a chromosome-scale assembly of Miscanthus lutarioriparius genome by combining Oxford Nanopore sequencing and Hi-C technologies. The 2.07-Gb assembly covers 96.64% of the genome, with contig N50 of 1.71 Mb. The centromere and telomere sequences are assembled for all 19 chromosomes and chromosome 10, respectively. Allotetraploid origin of the M. lutarioriparius is confirmed using centromeric satellite repeats. The tetraploid genome structure and several chromosomal rearrangements relative to sorghum are clearly demonstrated. Tandem duplicate genes of M. lutarioriparius are functional enriched not only in terms related to stress response, but cell wall biosynthesis. Gene families related to disease resistance, cell wall biosynthesis and metal ion transport are greatly expanded and evolved. The expansion of these families may be an important genomic basis for the enhancement of remarkable traits of M. lutarioriparius.

Water Use Efficiency and Stress Tolerance of the Potential Energy Crop Miscanthus lutarioriparius Grown on the Loess Plateau of China

As a potential energy crop with high biomass yield, Miscanthus lutarioriparius (M. lutarioriparius), endemic to the Long River Range in central China, needs to be investigated for its acclimation to stressful climatic and soil conditions often found on the marginal land. In this study, traits related to acclimation and yield, including survival rates, plant height (PH), stem diameter (SD), tiller number (TN), water use efficiency (WUE), and photosynthetic rates (A), were examined for 41 M. lutarioriparius populations that transplanted to the arid and cold Loess Plateau of China. The results showed that the average survival rate of M. lutarioriparius populations was only 4.16% over the first winter but the overwinter rate increased to 35.03% after the second winter, suggesting that plants having survived the first winter could have acclaimed to the low temperature. The strikingly high survival rates over the second winter were found to be 95.83% and 80.85%, respectively, for HG18 and HG39 populations. These populations might be especially valuable for the selection of energy crops for such an area. Those individuals surviving for the two consecutive winters showed significantly higher WUE than those measured after the first winter. The high WUE and low stomatal conductance (gs) observed in survived individuals could have been responsible for their acclimation to this new and harsh environment. A total of 61 individuals with productive growth traits and strong resistance to cold and drought were identified for further energy crop development. This study showed that the variation of M. lutarioriparius held great potential for developing energy crops following continuous field selection.

Chromosome-scale assembly and analysis of biomass crop Miscanthus lutarioriparius genome

The genus Miscanthus, a rhizomatous perennial plant, has great potential for bio-energy production for its high biomass yield and strong stress resistance. Here, we generated the first chromosome-scale assembly of Miscanthus lutarioriparius Nandi by combining Oxford Nanopore sequencing and Hi-C technologies. The 2.07-Gb assembly covers 96.64% of the genome, with contig N50 of 1.71 Mb. By utilizing Hi-C data, 1,956.46 Mb (94.30%) of the assembled sequences were anchored and oriented to 19 pseudochromosomes of haploid M. lutarioriparius. The diploid M. lutarioriparius was identified to have a typical tetraploid genome structure. With the chromosome-level genome assembly, a series of structural variation, including chromosomal fragmentation, fusion and rearrangement relative to sorghum genome were clearly characterized. The tandem duplicate genes of M. lutarioriparius were enriched not only in the GO terms related to biotic and abiotic stress response, but also in the cell wall biosynthesis. Comparative genome analysis revealed that the gene families related to disease resistance, cell wall biosynthesis and metal ion transport were greatly expanded and evolved. The gene families associated with the distinctive features of M. lutarioriparius were analyzed in detail, involving cell wall biosynthesis, disease resistance and C4 photosynthesis pathways. Besides the recent whole genome duplication, tandem duplication has played critical role in the expansion of size of these gene families investigated. While the transcriptome data showed that most duplicated gene members had extremely low level of expression in all transcriptome samples or the expected sample. The expansion of these families probably be an important genomic basis for the enhancement of those remarkable traits of M. lutarioriparius. These candidate gene members also provide valuable gene resource for function analysis and genetic improvement for M. lutarioriparius.

Assembly of 23 Plastid Genomes Provides the Chloroplast View on Miscanthus Origins

Despite its economic importance as a new biofuel resource, little work has been done on the large-scale phylogenetics of Miscanthus. Twenty-three complete Miscanthus chloroplasts were assembled and annotated. A phylogeny was performed with these assemblies, which shows the relationships between the main Miscanthus species and sub-species. The phylogeny demonstrates that there is no meaningful distinction between Miscanthus floridulus and Miscanthus transmorrisonensis as the accessions are not distinct. However, at the crown of the tree there is a clear distinction between M. sinensis malepartus and M. sinensis condensatus subspecies. The phylogeny reaveals that the female parent of Miscanthus xgiganteus is Miscanthus lutarioriparius rather than Miscanthus sacchariflorus. The phylogeny also shows a novel hybrid between Miscanthus oligostachyus and Miscanthus sinensis, a grouping to which Miscanthus sinensis var Purpurascens belongs. This hybrid form is named Miscanthus ×oligostachyus.