三倍体芒草自然杂交后代数量性状遗传多样性研究

以三倍体芒草奇岗的自然杂交后代为研究对象,对后代群体的16个数量性状分别进行变异分析、主成分分析和聚类分析。研究结果表明:(1)该杂交群体的变异系数在14.41%~151.85%之间,平均变异系数为51.22%,说明杂交后代变异广泛。(2)主成分分析结果表明,前4个主成分反映原变量的80.206%的信息。第1主成分贡献率为48.74%,较大载荷性状有分蘖数、丛径、基部周长、单株鲜重和单株干重;第2主成分贡献率为16.313%,较大载荷性状有外径、内径、单茎干重、单茎鲜重和含水量;第3主成分贡献率为7.775%,仅有腋芽数一个较大载荷性状;第4主成分贡献率为7.378%,仅叶片数一个较大载荷。(3)聚类分析结果表明,将66份奇岗自然杂交后代和6份母本奇岗种质分为4大类。第Ⅰ类材料因本身各性状不足,产量很低,不适合筛选高产种质;第Ⅱ类材料各性状变异系数普遍较小,性状稳定,适合作为育种的备选类群;第Ⅲ类材料因枯黄较少,更适合做发酵类能源草或青贮牧草;第Ⅳ类材料生物产量因子及其产量构成因子都明显优于母本,是较好的育种材料。以上研究结果对筛选芒属植物优良种质、创新芒属植物种质资源有积极意义,并为芒属植物多倍体育种提供理论依据和材料基础。     

Does greater leaf‐level photosynthesis explain the larger solar energy conversion efficiency of Miscanthus relative to switchgrass?

C₄ perennial grasses are being considered for bioenergy because of their high productivity and low inputs. In side-by-side replicated trials, Miscanthus ( Miscanthus x giganteus ) has previously been found more than twice as productive as switchgrass ( Panicum virgatum ). The hypothesis that this difference is attributable to higher leaf photosynthetic rates was tested on established plots of switchgrass and Miscanthus in central Illinois with >3300 individual measurements on 20 dates across the 2005 and 2006 growing seasons. Seasonally integrated leaf-level photosynthesis was 33% higher in Miscanthus than switchgrass ( P  < 0.0001). This increase in carbon assimilation comes at the expense of additional transpiration since stomatal conductance was on average 25% higher in Miscanthus ( P  < 0.0001). Whole-chain electron transport rate, measured simultaneously by modulated chlorophyll fluorescence, was similarly 23% higher in Miscanthus ( P  < 0.0001). Efficiencies of light energy transduction into whole chain photosynthetic electron transport, leaf nitrogen use and leaf water use were all significantly higher in Miscanthus. These may all contribute to its higher photosynthetic rates, and in turn, productivity. Systematic measurement of photosynthesis over two complete growing seasons in the field provides a unique dataset explaining why the productivity of these two species differs and for validating mechanistic production models for these emerging bioenergy crops.     

Structure of Ovarian Asterosaponin-1 in the Starfish Asterias amurensis

Cultured crown gall cells of Catharanthus roseus Don (Vinca rosea L.) was found to contain brassinosteroids. These were identified as brassinolide and castasterone by GC/MS. This is the first conclusive identification of endogenous brassinosteroids in cultured cells.     

Contrasting geographic patterns of genetic variation for molecular markers vs. phenotypic traits in the energy grass Miscanthus sinensis

Species and hybrids of Miscanthus are a promising energy crop, but their outcrossing mating systems and perennial life cycles are serious challenges for breeding programs. One approach to accelerating the domestication of Miscanthus is to harness the tremendous genetic variation that is present within this genus using phenotypic data from extensive field trials, high‐density genotyping and sequencing technologies, and rapidly developing statistical methods of relating phenotype to genotype. The success of this approach, however, hinges on detailed knowledge about the population genetic structure of the germplasm used in the breeding program. We therefore used data for 120 single‐nucleotide polymorphism and 52 simple sequence repeat markers to depict patterns of putatively neutral population structure among 244 Miscanthus genotypes grown in a field trial near Aberystwyth (UK) and delineate a population of 145 M . sinensis genotypes that will be used for association mapping and genomic selection. Comparative multivariate analyses of molecular marker and phenotypic data for 17 traits related to phenology, morphology/biomass, and cell wall composition revealed significant geographic patterns in this population. A longitudinal cline accounted for a substantial proportion of molecular marker variation (R² = 0.60, P = 3.4 × 10^?15). In contrast, genetic variation for phenotypic traits tended to follow latitudinal and altitudinal gradients, with several traits appearing to have been affected by divergent selection (i.e., Q_ST >> F_ST). These contrasting geographic trends are unusual relative to other plants and provide opportunities for powerful studies of phenotype–genotype associations and the evolutionary history of M. sinensis.     

中国芒（Miscanthus sinensis）种质资源SSR标记遗传多样性分析

利用33对SSR引物对来自中国16个省的46份野生芒(Miscanthus sinensis)种质进行遗传多样性分析。结果显示:(1)33对SSR引物共扩增出87条DNA条带,75条为多态性条带,占86.21%,条带大小范围80～310 bp;(2)遗传多样性参数分析结果:Shannon’s信息指数(I)变幅为0.020～1.522,平均为0.745,引物多态性信息含量(PIC)变幅为0.040～0.738,平均为0.445,遗传相似系数(GS)的变幅为0.315～0.933,平均为0.569,说明我国芒种质资源遗传基础宽,遗传多样性丰富;(3)相似系数UMPGA聚类结果与主成分分析(PCA)结果一致,可将46份种质分为3大类群,类群Ⅰ主要由中部芒组成,类群Ⅱ主要由北方芒组成,类群Ⅲ主要由南方芒组成,西南芒在每个类群中均有渗透,这一结果说明芒种质资源的遗传分化与其种源的地理分布有一定的相关性,但与地理起源不能完全吻合。     

Yield‐biodiversity trade‐off in patchy fields of Miscanthus × giganteus

Increasing crop productivity to meet rising demands for food and energy, but doing so in an environmentally sustainable manner, is one of the greatest challenges for agriculture to date. In Ireland, Miscanthus × giganteus has the potential to become a major feedstock for bioenergy production, but the economic feasibility of its cultivation depends on high yields. Miscanthus fields can have a large number of gaps in crop cover, adversely impacting yield and hence economic viability. Predominantly positive effects of Miscanthus on biodiversity reported from previous research might be attributable to high crop patchiness, particularly during the establishment phase. The aim of this research was to assess crop patchiness on a field scale and to analyse the relationship between Miscanthus yield and species richness and abundance of selected taxa of farmland wildlife. For 14 Miscanthus fields at the end of their establishment phase (4–5 years after planting), which had been planted either on improved grassland (MG) or tilled arable land (MT), we determined patchiness of the crop cover, percentage light penetration (LP) to the lower canopy, Miscanthus shoot density and height, vascular plants and epigeic arthropods. Plant species richness and noncrop vegetation cover in Miscanthus fields increased with increasing patchiness, due to higher levels of LP to the lower canopy. The species richness of ground beetles and the activity density of spiders followed the increase in vegetation cover. Plant species richness and activity density of spiders on both MT and MG fields, as well as vegetation cover and activity density of ground beetles on MG fields, were negatively associated with Miscanthus yield. In conclusion, positive effects of Miscanthus on biodiversity can diminish with increasing productivity. This matter needs to be considered when assessing the relative ecological impacts of developing biomass crops in comparison with other land use.     

Mapping the genome of Miscanthus sinensis for QTL associated with biomass productivity

In light of rising energy costs, lignocellulosic ethanol has been identified as a renewable alternative to petroleum-based transportation fuels. In an attempt to reach government mandated ethanol production levels, potential plant biofeedstock candidates have been investigated, and cold-tolerant, perennial accessions within the C₄ grass genus Miscanthus have been identified as leading contenders in the Midwestern US. To facilitate the development of improved cultivars through marker-assisted breeding, a quantitative trait locus (QTL) study was conducted on a full-sib, F₁ mapping population segregating for flowering time, height, leaf width, and yield using a genetic map consisting of 846 segregating SNP and SSR markers. This was a 3 year study investigating the genetic architecture underlying traits important to biomass production in a population of 221 progeny from a cross between M. sinensis ‘Grosse Fountaine’ and M. sinensis ‘Undine’ established in the spring of 2010; 72 QTLs with LOD scores above the genome-wide, permuted threshold equivalent to a P-value of 0.05 were identified across 13 traits. Of the 36 QTLs identified in 2011, 22 were detected again the following year. Both the use of spring emergence and vigor rating as a covariate to account for variation related to differences in establishment increased the power to detect QTLs in the 2 year establishment period. Finally, a dry period in the middle of the 2012 growing season suggested that yield declines were due to a decrease in tiller diameter.     

European-wide GIS-based modelling system for quantifying the feedstock from Miscanthus and the potential contribution to renewable energy targets

Reliable estimates of feedstock resources are a prerequisite to the establishment of a biomass based-industry for energy and non food products. Field trials in the European Union (EU) show that Miscanthus spp. can produce high yields. Here we use a model (MISCANMOD) coupled with a GIS environment to estimate the contribution that Miscanthus could make to projected national electricity consumption. We describe the integration of different data sets, transformation procedures, and spatial analyses using GIS to produce energy statistics for the EU-25. Overall, Miscanthus grown on the 10% of arable land which is currently in set-aside could generate 282 TWh yr⁻¹ electricity. This would meet 39% of the EU-25 target of 723 TWh yr⁻¹ of electricity from renewable energy sources (RES) by 2010. As RES targets rise, land available for energy crops is also expected to increase. We consider three additional scenarios where Miscanthus could be grown on 10%, 20% and 35% of all agricultural land and we estimate it could generate respectively 345, 691 and 1209 TWh yr⁻¹ of electrical energy. At a national scale France, Poland and Germany have the highest potentials for Miscanthus production based on agricultural land area (respectively 83, 52, 49 TWh yr⁻¹ when 10% agricultural land is used). Finally, we reduced the scale to the EU NUTS2 (Nomenclature of Territorial Units for Statistics) regions to examine regional generation capacities. Key regions have been identified where national RES targets are exceeded. These regions could become net exporters of renewable energy.