Assessment of genetic diversity of native species in Izu Islands for a discriminate choice of source populations: Implications for revegetation of volcanically devastated sites

In using native species for revegetation, it is necessary choose source populations carefully to reduce the risk of planting suboptimal germplasm. To make preliminary recommendations for native species to use in the revegetation of a volcanically devastated area on Miyake Is., Japan, we investigated the genetic variation of Alnus sieboldiana, Miscanthus sinensis ssp. condensatus, and Polygonum cuspidatum var. terminalis in the Izu Islands and on the Izu Peninsula based on chloroplast DNA (cpDNA) sequence variations and amplified fragment length polymorphisms (AFLPs). The amount and pattern of differentiation differ between organelle and nuclear markers, suggesting the necessity of evaluation based on both types of markers. Within-population diversity did not vary among populations, suggesting that it does not need to be considered in the choice of a source population. The pattern and degree of differentiation varied among species, and geographical proximity did not necessarily accord with genetic similarity, suggesting that the site of an appropriate source population varies among species and should be determined empirically rather than by assuming that close proximity predicts genetic similarity. The Izu Peninsula populations deviated from the island populations in all species. Comparison of cpDNA sequences with those of related species indicates the possibility of hybridization with related species on the Izu Peninsula, suggesting that seeds collected from populations where related species live sympatrically should not be used for revegetation. These findings indicate the need to assess the genetic diversity empirically by using organelle and nuclear markers to avoid unintended consequences of genetic mixing associated with revegetation.     

Phylogenetics of Miscanthus,Saccharum and related genera (Saccharinae,Andropogoneae, Poaceae) based on DNA sequences from ITS nuclear ribosomal DNA and plastid trnLintron and trnL-F intergenic spacers

DNA sequences were used to assess the monophyly and inter-relationships of Miscanthus, Saccharum and related genera in the Saccharum complex. Three DNA regions were sequenced, including the trnL intron and the trnL-F intergenic spacer of the plastid genome and the ITS region of nuclear ribosomal DNA (nrDNA). Because it was more variable, the ITS region proved most suitable for phylogenetic reconstruction at this level, and the results indicate that Miscanthus s.l. and Saccharum s.l. are polyphyletic. A set of species from Saccharum section Ripidium (clade a) do not group closely with any members of Saccharum s.l.. A number of Miscanthus species from eastern or south-eastern Asia represent a monophyletic group with a basic chromosome number of 19 (clade b), but the other species from Africa and the Himalayas are clearly excluded. There is support for a monophyletic Saccharum s.s. clade including S. officinarum and S. spontaneum that is sister to Miscanthus s.s (clade c). There is no evidence to support the division of some Saccharum s.l. into the genera currently known as Erianthus and Narenga. Saccharum contortum (=Erianthus contortus), S. narenga (=Narenga porphyrocoma) and Erianthus rockii, group more closely with Miscanthus fuscus, a species from the Himalayas and also with the African Miscanthus s.l. species (=Miscanthidium, clade d). Electronic Publication     

Modelling the carbon cycle of Miscanthus plantations: existing models and the potential for their improvement

The lignocellulosic perennial grass Miscanthus has received considerable attention as a potential bioenergy crop over the last 25 years, but few commercial plantations exist globally. This is partly due to the uncertainty associated with claims that land‐use change (LUC) to Miscanthus will result in both commercially viable yields and net increases in carbon (C) storage. To simulate what the effects may be after LUC to Miscanthus, six process‐based models have been parameterized for Miscanthus and here we review how these models operate. This review provides an overview of the key Miscanthus soil organic matter models and then highlights what measurers can do to accelerate model development. Each model (WIMOVAC, BioCro, Agro‐IBIS, DAYCENT, DNDC and ECOSSE) is capable of simulating biomass production and soil C dynamics based on specific site characteristics. Understanding the design of these models is important in model selection as well as being important for field researchers to collect the most relevant data to improve model performance. The rapid increase in models parameterized for Miscanthus is promising, but refinements and improvements are still required to ensure that model predictions are reliable and can be applied to spatial scales relevant for policy. Specific improvements, needed to ensure the models are applicable for a range of environmental conditions, come under two categories: (i) increased data generation and (ii) development of frameworks and databases to allow simulations of ranging scales. Research into nonfood bioenergy crops such as Miscanthus is relatively recent and this review highlights that there are still a number of knowledge gaps regarding Miscanthus specifically. For example, the low input requirements of Miscanthus make it particularly attractive as a bioenergy crop, but it is essential that we increase our understanding of the crop's nutrient remobilization and ability to host N‐fixing organisms to derive the most accurate simulations.     

The Tolerance and Accumulation of Miscanthus Sacchariflorus (maxim.) Benth., an Energy Plant Species,to Cadmium

Miscanthus sacchariflorus (Maxim.) Benth. is a metallophyte suitable for the phytoremediation of mine wastes. The tolerance and accumulation of M. sacchariflorus to cadmium was studied by pot experiments. The results showed that O₂·^? generation rate, plasma membrane permeability and MDA content of M. sacchariflorus leaves increased with increasing Cd concentrations in soil, but significant effect was only observed when Cd concentrations were ≥ 50 mg·kg^?1. SOD and POD activities increased initially but decreased later on, whereas CAT activity only increased significantly at higher Cd concentrations, 50–100 mg·kg^?1. The content of photosynthetic pigment and growth of M. sacchariflorus were both not significantly affected when Cd concentration was ≤ 25 mg·kg^?1. In contrast, both parameters were significantly affected when Cd concentration was ≥ 50 mg·kg^?1. M. sacchariflorus could accumulate much Cd, but most of the Cd assimilated was retained in the belowground part, suggesting that M. sacchariflorus has poor ability to translocate Cd to the aboveground part. Our results suggested that although M. sacchariflorus was not a hyper-accumulator, it has a strong capacity to tolerate and stabilize the Cd. Therefore, M. sacchariflorus has a certain potential in the phytostabilization of Cd-contaminated soils.     

Genotypic variation of cell wall composition and its conversion efficiency in Miscanthus sinensis,a potential biomass feedstock crop in China

Plant cell walls are composed of cellulose microfibrils embedded in a cross‐linked‐net of matrix polysaccharides and co‐polymerized with lignin. The study presented the genotypic variations of cell wall composition, biohydrogen production, and lignocellulose degradation ratio in a collection of 102 Miscanthus sinensis (M. Sinensis, hereafter) accessions collected from a wide geographical range in China. Significant variations were observed for the determined traits, cellulose content, hemicellulose content, cellulose and hemicellulose degradation efficiency, and biohydrogen yield. The cellulose, hemicellulose, and lignin contents ranged from 30.20–44.25, 28.97–42.65, and 6.96–20.75%, respectively. The degradation ratio of cellulose and hemicellulose varied from 2.08% to 37.87% and from 14.71% to 52.50%, respectively. The feedstock was fermented to produce biohydrogen, and the production varied from 14.59 to 40.66 ml per gram of Miscanthus biomass. The expression profile of three cellulose synthase (MsCesA) genes was initially established to indicate the genotypic difference among the M. sinensis accessions. Pearson's correlations were conducted to reveal the perplexing relationship between the tested traits, biohydrogen yield, cell wall composition and their degradation efficiency. In addition, the relationship pattern, between the test traits and the geographic factors corresponding with the original place, was investigated. The result showed that the significant variation among the M. sinensis genotypes is the result of natural selection in different environments of their original habitats. Improvement in cell wall composition and structure and enhancement of lignocellulose degradation ratio could significantly increase sustainable bioenergy production.     

五节芒基因组大小测定

五节芒(Miscanthus floridulus)属于禾本科(Poaceae)芒属(Miscanthus Andersson),被认为是一种开发潜力巨大的生物质能源植物。本研究以水稻日本晴(Oryza sativa L.var.Nipponbare)为内标,采用流式细胞仪测定6份采自中国不同地区的五节芒基因组大小。结果首次确定了五节芒的基因组大小平均为2596.59 Mb,即2 C DNA含量为5.31 pg(以1 pg=978 Mb计算)。     

Differential Responses of <i>NHX1</i> and <i>SOS1</i> Gene Expressions to Salinity in two <i>Miscanthus sinensis</i> Anderss. Accessions with Different Salt Tolerance

The lignocellulosic crop Miscanthus spp. has been identified as a good candidate for biomass production. The responses of Miscanthus sinensis Anderss. to salinity were studied to satisfy the needs for high yields in marginal areas and to avoid competition with food production. The results indicated that the relative advantages of the tolerant accession over the sensitive one under saline conditions were associated with restricted Na⁺ accumulation in shoots. Seedlings of two accessions (salt-tolerant ‘JM0119’ and salt-sensitive ‘JM0099’) were subjected to 0 (control), 100, 200, and 300 mM NaCl stress to better understand the salt-induced biochemical responses of genes involved in Na⁺ accumulation in M. sinensis. The adaptation responses of genes encoding for Na⁺ /H⁺ antiporters, NHX1 and SOS1 to NaCl stress were examined in JM0119 and JM0099.The cDNA sequences of genes examined were highly conserved among the relatives of M. sinensis based on the sequencing on approximate 600 bp-long cDNA fragments obtained from degenerate PCR. These salt-induced variations of gene expression investigated by quantitative real-time PCR provided evidences for insights of the molecular mechanisms of salt tolerance in M. sinensis. The expression of NHX1 was up-regulated by salt stress in JM0119 shoot and root tissues. However, it was hardly affected in JM0099 shoot tissue except for a significant increase at the 100 mM salt treatment, and it was salt-suppressed in the JM0099 root tissue. In the root tissue, the expression of SOS1 was induced by the high salt treatment in JM0119 but repressed by all salt treatments in JM0099. Thus, the remarkably higher expression of NHX1 and SOS1 were associated with the resistance to Na⁺ toxicity by regulation of the Na⁺ influx, efflux, and sequestration under different salt conditions.     

Bioethanol production from dedicated energy crops and residues in Arkansas, USA

Globally, one of the major technologic goals is to achieve cost-effective lignocellulosic ethanol production from biomass feedstocks. Lignocellulosic biomass of four dedicated energy crops [giant reed (Arundo donax L.), elephantgrass (Pennisetum purpureum (Schumach), Miscanthus × giganteus (Illinois clone), and (clone Q42641) {hybrid of Miscanthus sinensis Anderss. and Miscanthus sacchariflorus (Maxim)}, Hack. called giant miscanthus, and sugarcane clone US 84-1028 (Saccharum L. spp. hybrid)] and residues from two crops [soybean (Glycine max (L.) Merr.) litter and rice (Oryza sativa L.) husk] were tested for bioethanol production using cellulose solvent-based lignocellulose fractionation (CSLF) pretreatment and enzymatic (cellulase) hydrolysis. Giant miscanthus (Illinois), giant reed, giant miscanthus (Q42641), elephantgrass, and sugarcane all yielded higher amount of glucose on a biomass dry weight basis (0.290-0.331 g/g), than did rice husk (0.181 g/g) and soybean litter (0.186 g/g). To reduce the capital investment for energy consumption in fermentation, we used a self-flocculating yeast strain (SPSC01) to ferment the lignocellulosic biomass hydrolysates. Bioethanol production was ～0.1 g/g in dedicated energy crops and less in two crop residues. These methods and data can help to develop a cost-effective downstream process for bioethanol production.