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。     

Miscanthus×giganteus plant regeneration: effect of callus types,ages and culture methods on regeneration competence

The perennial rhizomatous grass, Miscanthus×giganteus is an ideal biomass crop due to its rapid vegetative growth and high biomass yield potential. As a naturally occurring sterile hybrid, M. ×giganteus must be propagated vegetatively by mechanically divided rhizomes or from micropropagated plantlets. Plant regeneration through somatic embryogenesis is a viable approach to achieve large‐scale production of plantlets in tissue culture. Effect of the callus types, ages and culture methods on the regeneration competence was studied to improve regeneration efficiency and shorten the period of tissue culture in M. ×giganteus. Shoot‐forming calli having a yellow or white compact callus with light‐green shoot‐like structures showed the highest regeneration frequency. Percentage of shoot‐forming callus induction from immature inflorescence explants was 41% on callus induction medium containing 13.6 μM 2,4‐d and 0.44 μM benzyladenine (BA). The use of a regeneration medium containing 1.3 μM NAA and 22 μM BA was effective at shortening the incubation period required for plantlet regeneration, with 69% of total regenerated plantlets obtained within 1 month of incubation on regeneration medium. Embryogenic‐like callus morphotype could maintain regeneration competency for up to 1 year as suspension cultures. Field grown regenerated plants showed normal phenotypic development with DNA content and plant heights comparable to rhizome propagated plants. Winter survival rates of the regenerated plants planted in 2006 and 2007 at the University of Illinois South Farm, Urbana‐Champaign, Illinois, were 78% and 56%, respectively.     

芒和五节芒在中国的潜在分布

利用最大熵模型, 将我国现有芒(Miscanthus sinensis)和五节芒(M. floridulus)的地理分布信息与19个降水及温度等气候因子相拟合, 预测了芒和五节芒在我国的潜在分布区域, 并推测出芒和五节芒的基本生态位。结果显示: 芒的潜在适生区包括四川西部、陕西北部、宁夏、内蒙古中部、黑龙江、吉林西部、辽宁西部、青海东南部等地区, 其基本生态位参数为: 最暖季节降水量为400-1 000 mm, 平均8月降水量为100-350 mm, 7月平均最低气温为15 ℃, 平均7月降水量为100-350 mm, 11月平均最高气温为-10-22 ℃, 最干月平均气温为-15-20 ℃, 平均12月降水量为100 mm以下; 五节芒的潜在适生区为云南、陕西、山西、宁夏、河南、山东、吉林、辽宁以及四川西部、甘肃南部和内蒙古东部等地区, 其基本生态位参数为: 最暖季节降水量至少在400 mm以上, 平均6月降水量为150-550 mm, 7月平均最低气温在15-30 ℃之间, 6月平均最低气温为10 ℃, 平均4月降水量为50-100 mm。结果表明, 在进行遗传改良的前提下, 我国有丰富的适合栽植芒和五节芒的土地资源。     

五节芒定居对尾矿砂重金属形态、微生物群落功能及多样性的影响

选择尾矿砂裸地和4个五节芒(Miscanthus floridulus)定居地(RI、RII、RIII和RIV)为样地, 分别研究了五节芒定居对尾矿砂重金属形态转化和微生物功能参数的影响。结果表明: 五节芒自然定居显著地提高了尾矿砂碳酸盐结合态和硫化物-有机物结合态重金属比例(p＜0.05), 降低了尾矿砂残渣态重金属的比例(p＜0.05)。土壤微生物群落的纤维素分解作用、酚转化作用、固氮作用、氨化作用、硝化作用、有机磷转化作用、功能多样性、4类不同碳源(碳水化合(CH)、聚合物(PL)、胺类化合物(AM)和杂合物(ML))均随着五节芒自然定居显著提高(p＜0.05)。而氨基酸(AA)的利用强度却显著下降(p＜0.05)。典范相关分析(CCA)表明: 土壤微生物功能参数的总体变化与土壤碳酸盐结合态和硫化物-有机物结合态重金属的含量呈显著正相关, 与残渣态重金属含量呈显著负相关。该研究结果表明, 五节芒定居不仅促进了尾矿砂重金属朝着沉淀态和螯合态方面转化, 而且还显著地改善了尾矿砂微生物群落的功能发挥。因而, 五节芒在重金属矿业废弃地恢复实践中具有较大的应用潜力。     

Shoot growth, radiation interception and dry matter production and partitioning during the establishment phase of Miscanthus sinensis'Giganteus' grown at two densities in the UK

Photosynthetic area index (PAI), radiation interception (I) and dry matter partitioning between shoots and roots were measured for Miscanthus sinensis‘Giganteus' grown from micro-propagated transplants on a fertile peaty loam soil in eastern England. In the establishment year, Miscanthus plants produced 35 and 70 shoots plant^-1 at densities of 4.0 and 1.8 plants m^-2 respectively. At the higher density, there were 140 shoots m^-2 with the largest reaching a height of 1.8 m; these canopies attained a maximum PAI of 5.45, intercepting 94% of incident radiation. Leaf lamina contributed c. 90% of total photosynthetic area with stems contributing the remainder. At the lower density, maximum PAI and I values were 2.88 and 86% respectively. PAI was related to I by calculating attenuation coefficients (k); these indicated that Miscanthus canopies were more effective at intercepting radiation per unit PAI at the lower density (k= -0.31) compared with the higher density (k= -0.20). Radiation interception was related to dry matter accumulated by calculating conversion efficiencies (e). At 4 plants m^-2, × for shoot dry matter production was 1.17g MJ^-1. Miscanthus partitioned a relatively large amount of total dry matter into below-ground biomass. By plant senescence, c. 30% of total dry matter had been partitioned into root and rhizome; rhizome biomass contributed 80% of below-ground dry matter, × increased to 1.62 g MJ^-1 when calculated on a total dry matter basis (shoot + root + rhizome). Total dry matter production was increased 68% by a 2.2-fold increase in plant density.     

Genetic variation and bidirectional gene flow in the riparian plant Miscanthus lutarioriparius,across its endemic range: implications for adaptive potential

Miscanthus lutarioriparius is an endemic species that grows along the middle and lower reaches of the Yangtze River and is a valuable source of germplasm for the development of second‐generation energy crops. The plant that propagates via seeds, stem nodes, and rhizomes shows high phenotypic variation and strong local adaptation. Here, we examined the magnitude and spatial distribution of genetic variation in M. lutarioriparius across its entire distributional range and tested underlying factors that shaped its genetic variation. Population genetic analyses were conducted on 644 individuals from 25 populations using 16 microsatellite markers. M. lutarioriparius exhibited a high level of genetic variation (H_E = 0.682–0.786; A_r = 4.74–8.06) and a low differentiation (F_ST = 0.063; D_est = 0.153). Of the total genetic variation, 10% was attributed to the differences among populations (df = 24, P < 0.0001), whereas 90% was attributed to the differences among individuals (df = 619, P ≤ 0.0001). Genetic diversity did not differ significantly across longitudes and did not increase in the populations growing downstream of the Yangtze River. However, significant associations were found between genetic differentiation and spatial distance. Six genetic discontinuities were identified, which mostly distributed among downstream populations. We conclude that anthropogenic factors and landscape features both contributed to shaping the pattern of gene flow in M. lutarioriparius, including long‐distance bidirectional dispersal. Our results explain the genetic basis of the high degree of adaptability in M. lutarioriparius and identify potential sources of new germplasm for the domestication of this potential second‐generation energy crop.     

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.     

部分落叶松属植物核型研究

对落叶松属的兴安落叶松、长白落叶松、日本落叶松、华北落叶松、欧洲落叶松、美洲落叶松等6个种和日本落叶松×长白落叶松杂种进行了核型分析,所有材料的染色体数目均为2n=2x=24,2A核型。所有种的核型有着共同的构型,即二型核型。根据核型特征,可将以上各种分为三组:兴安落叶松、长白落叶松、日本落叶松为第一组,核型公式为2n=12m+10sm+2st;欧洲落叶松、美洲落叶松为第二组,核型公式为2n=12m+12sm;华北落叶松虽然具有与第二组相同的核型公式,但核型的对称性与其有一定差距,因此单独构成第三组。日本落叶松×长白落叶松杂种的核型数据和两个亲本的十分接近,表明这两个种杂交后染色体可能未发生明显的结构变异。作者认为长白落叶松和兴安落叶松的核型特征比较接近,从细胞学的角度作者支持长白落叶松作为兴安落叶松变种的观点。