Phylogenetic analysis reveals multiple introductions of Cynodon species in Australia

The distinction between native and introduced flora within isolated land masses presents unique challenges. The geological and colonisation history of Australia, the world's largest island, makes it a valuable system for studying species endemism, introduction, and phylogeny. Using this strategy we investigated Australian cosmopolitan grasses belonging to the genus Cynodon. While it is believed that seven species of Cynodon are present in Australia, no genetic analyses have investigated the origin, diversity and phylogenetic history of Cynodon within Australia. To address this gap, 147 samples (92 from across Australia and 55 representing global distribution) were sequenced for a total of 3336bp of chloroplast DNA spanning six genes. Data showed the presence of at least six putatively introduced Cynodon species (C. transvaalensis, C. incompletus, C. hirsutus, C. radiatus, C. plectostachyus and C. dactylon) in Australia and suggested multiple recent introductions. C. plectostachyus, a species often confused with C. nlemfuensis, was not previously considered to be present in Australia. Most significantly, we identified two common haplotypes that formed a monophyletic clade diverging from previously identified Cynodon species. We hypothesise that these two haplotypes may represent a previously undescribed species of Cynodon. We provide further evidence that two Australian native species, Brachyachne tenella and B. convergens belong in the genus Cynodon and, therefore, argue for the taxonomic revision of the genus Cynodon.     

Characterization and multiplexing of EST-SSR primers in Cynodon (Poaceae) species1

? Premise of the study: Cynodon species are multiple-use grasses that display varying levels of adaptation to biotic and abiotic stress. Previously identified EST-SSR primers were characterized and multiplexed to assess the level of genetic diversity present within a collection of almost 1200 Cynodon accessions from across Australia. ? Methods and Results: Two multiplex reactions were developed comprising a total of 16 EST-SSR markers. All SSR markers amplified across different Cynodon species and different levels of ploidy. The number of alleles ranged from one to eight per locus and the total number of alleles for the germplasm collection was 79. ? Conclusions: The 16 markers show sufficient variation for the characterization of Cynodon core collections and analysis of population genetic diversity in Cynodon grasses.     

河滨湿地不同植物群落根系分布特征与土壤理化性状的关系——以黄河中游荥阳段为例

在黄河中游郑州荥阳段,选择了5种河滨湿地植物群落进行根系和土壤性状特征研究,以期阐明不同植物群落的根系分布规律与土壤性状的关系,为河滨湿地植物群落组成以及土壤质量恢复提供科学参考。结果表明(1)在0—40 cm土层,根生物量密度与根长密度的平均值均表现为：芦苇群落(Phragmites australis)和芦苇-狗牙根(Cynodon dactylon)群落均大于芦苇-拂子茅(Calamagrostis epigeios)-狗牙根群落、拂子茅-狗牙根群落、拂子茅-狗牙根-水莎草(Juncellus serotinus)群落。拂子茅-狗牙根、芦苇-拂子茅-狗牙根、拂子茅-水莎草-狗牙根三种植物群落类型下根生物量密度、根长密度在0—20 cm表层土壤较大,芦苇群落和芦苇-狗牙根群落的根生物量密度、根长密度在10—40 cm的土层较大。(2)黄河河滨湿地芦苇群落、芦苇-狗牙根群落的土壤以粉粒为主,拂子茅-狗牙根群落、芦苇-拂子茅-狗牙根群落、拂子茅-狗牙根-水莎草群落的土壤主要以砂粒为主。在0—40 cm土层,芦苇群落、芦苇-狗牙根群落的土壤含水率、土壤有机质、有效氮和有效磷含量均显著高于...     

The role of a plant/fungal consortium in the degradation of bituminous hard coal

The sporadic growth of Cynodon dactylon was observed to occur directly on the surface of hard coal in dumps of the Witbank coal mining area of South Africa with the surface coal being broken down into a humic-like particulate material. Microorganism analysis of plants and rhizosphere material from the dumps revealed the presence of arbuscular mycorrhizal fungi and the coal solubilising fungus, Neosartorya fischeri. Studies established to replicate the dump environment revealed increased coal degradation in the form of humic acid production and an increase in small size particles as a result of Cynodon dactylon growth in association with arbuscular mycorrhizal fungi and Neosartorya fischeri. Results suggest that interactions between Cynodon dactylon, arbuscular mycorrhizal fungi, Neosartorya fischeri and other coal-degrading rhizosphere fungi could lead to the degradation of hard coal in situ and that the application of these organisms to discard dumps could be a novel method of coal dump rehabilitation.     

Elucidating polyploidization of bermudagrasses as assessed by organelle and nuclear DNA markers

Clarification of relationships among ploidy series of Cynodon accessions could be beneficial to bermudagrass breeding programs, and would enhance our understanding of the evolutionary biology of this warm season grass species. This study was initiated to elucidate polyploidization among Cynodon accessions with different ploidy series collected from Turkey based on chloroplast and nuclear DNA. Forty Cynodon accessions including 7 diploids, 3 triploids, 10 tetraploids, 11 pentaploids, and 9 hexaploids were analyzed using chloroplast DNA restriction fragment-length polymorphism (cpDNA RFLP), chloroplast DNA simple sequence repeat (cpDNA SSR), and nuclear DNA markers based on neighbor-joining (NJ) and principle component analyses (PCA). All three-marker systems with two statistical algorithms clustered the diploids apart from the other ploidy levels. Assuming autopolyploidy, spontaneous polyploidization followed by rapid diversification among the higher ploidy levels than the diploids is likely in Cynodon's evolution. Few tetraploid and hexaploid accessions were clustered with or closely to the group of diploids, supporting the hypothesis above. Eleven haplotypes as estimated by cpDNA RFLP and SSR markers were detected. This study indicated that the diploids had different organelle genome from the rest of the ploidy series and provided valuable insight into relationships among ploidy series of Cynodon accessions based on cp and nuclear DNAs.     

Fate of heavy metals in vertical subsurface flow constructed wetlands treating secondary treated petroleum refinery wastewater in Kaduna,Nigeria

This study examined the performance of pilot-scale vertical subsurface flow constructed wetlands (VSF–CWs) planted with three indigenous plants, i.e. Typha latifolia, Cyperus alternifolius, and Cynodon dactylon, in removing heavy metals from secondary treated refinery wastewater under tropical conditions. The T. latifolia-planted VSF–CW had the best heavy metal removal performance, followed by the Cyperus alternifolius-planted VSF–CW and then the Cynodon dactylon-planted VSF–CW. The data indicated that Cu, Cr, Zn, Pb, Cd, and Fe were accumulated in the plants at all the three VSF–CWs. However, the accumulation of the heavy metals in the plants accounted for only a rather small fraction (0.09–16%) of the overall heavy metal removal by the wetlands. The plant roots accumulated the highest amount of heavy metals, followed by the leaves, and then the stem. Cr and Fe were mainly retained in the roots of T. latifolia, Cyperus alternifolius, and Cynodon dactylon (TF < 1), meaning that Cr and Fe were only partially transported to the leaves of these plants. This study showed that VSF–CWs planted with T. latifolia, Cyperus Alternifolius, and Cynodon dactylon can be used for the large-scale removal of heavy metals from secondary refinery wastewater.     

Leaf blade structure and C4 acid decarboxylation enzymes in xCynochloris spp. (Poaceae), intergeneric hybrids between species of different C4 type

PRENDERGAST, H. D. V., STONE, N. E. & HATTERSLEY, P. W., 1988. Leaf blade structure and C₄ acid decarboxylation enzymes in x Cynochloris spp. (Poaceae), intergeneric hybrids between species of different C₄ type. x Cynochloris macivorii Clifford and Everist and x C. reynoldensis B. K. Simon (Poaceae) are intergeneric C₄ hybrids between Cynodon dactylon (L.) Pers., and NAD-malic enzyme (NAD-ME) species, and two different PEP carboxykinase (PCK) species of Chloris . Parental species of each hybrid species have the 'classical' leaf blade structure of their respective C₄ acid decarboxylation types. The outline of the photosynthetic carbon reduction (PCR or Kranz) bundle sheath and the position of the PCR cell chloroplasts in x Cynochloris are intermediate between those of the parental species, C. macivorii being more like Cynodon dactylon and x C. reynoldensis more like Chloris spp. The PCR chloroplast shape in x C. macivorii and x C. reynoldensis is like that of Cynodon dactylon and Chloris spp., respectively. Differences between the hybrids in their enzyme activities complement these structural differences: x C. macivorii has more NAD—ME and less PCK activity than x C. reynoldensis , although in both species PCK activity is the greater. Both hybrids, however, have a suberized lamella in PCR cell walls as do Chloris spp. The close taxonomic relationship between Cynodon and Chloris make these genera especially suitable for reciprocal crossing experiments aimed at increasing understanding of the genetic relationships between subtypes of the C₄ photosynthetic pathway.     

不同基质中4种电网塔基地被植物种子发芽与幼苗生长研究

以宽叶雀稗(Paspalum wettsteinii)、百喜草(P. notatum)、狗牙根(Cynodon dactylon)和猪屎豆(Crotalaria pallida) 4种植物种子为材料,研究其在沙土、园土、红壤、建筑废弃土、碎石块等基质中萌发和幼苗生长情况,筛选4种植物最适栽培基质,以期为电网基塔下及四周裸露地面复绿提供指导。结果表明,沙土适于宽叶雀稗、百喜草、狗牙根种子发芽;猪屎豆在5种基质中均不发芽。宽叶雀稗适于红壤生长;百喜草、狗牙根适于园土生长;宽叶雀稗为沙土、建筑废弃土和碎石块上最适合栽种的植物。通过灰色关联度分析,3种植物苗期生长的综合排序为δ宽叶雀稗(0.553) > δ狗牙根(0.522) > δ百喜草(0.436),故在5种基质中,宽叶雀稗幼苗生长综合表现最佳。     

三峡库区消落带野生狗牙根对水淹适生性的转录组分析

为探究狗牙根对水淹环境的适生性机制,取长势一致的狗牙根分为未水淹对照组(A1)和30 cm沉水处理组(A2),A2水淹15 d后两组同时采样,提取样本总RNA作转录组测序。A1和A2测序数据经de novo组装分别获得128031和83363条高质量Unigene;A1和A2对比发现28844条差异表达基因(differentially expressed genes, DEGs),其中11858条DEGs上调表达,16986条DEGs下调表达;功能注释显示,这些DEGs主要集中在转录、翻译、碳水化合物代谢和环境适应等途径;信号通路富集显示,包括植物对病原体的防御、物质代谢、光合作用、形态发育和抗氧化等过程的103个信号通路与狗牙根对水淹生境的适生性有关;随机挑选4个DEGs作qRT-PCR分析,荧光定量结果与测序数据基本一致,说明基于转录组分析DEGs的表达情况较为可靠。该工作或可为进一步挖掘与狗牙根水淹适生性相关的调控基因和功能基因提供基础。     

湖南四种尾矿环境下的狗牙根遗传多样性的RAPD分析

选择湖南4种有代表性的有色金属尾矿地所生长的野生狗牙根作为研究对象,并以正常生境下的野生狗牙根作为对照,采用RAPD技术分析了这些特别环境下的狗牙根的遗传多样性。17条10个核苷酸长的引物用于PCR扩增,共得到432条DNA带。检测位点160个,其中多态位点134个,占83.75%。各个类群间的Jaccard相似系数平均为0.4475±0.0806,遗传距离平均为0.3825±0.0712。结果显示生长于这些不同尾矿环境下的狗牙根种群在遗传本质上均产生了明显的分化,完全可以根据其尾矿基质的不同而划分为不同的生态型或品种,甚至可能处理为新的变种。狗牙根种群具有丰富的遗传多样性,作为先锋植物可为尾矿的复垦提供更多的品种选择。     

Diversity among Cynodon accessions and taxa based on DNA amplification fingerprinting.

The genus Cynodon (Gramineae), comprised of 9 species, is geographically widely distributed and genetically diverse. Information on the amounts of molecular genetic variation among and within Cynodon taxa is needed to enhance understanding of phylogenetic relations and facilitate germplasm management and breeding improvement efforts. Genetic relatedness among 62 Cynodon accessions, representing eight species, was assessed using DNA amplification fingerprinting (DAF). Ten 8-mer oligonucleotides were used to amplify specific Cynodon genomic sequences. The DNA amplification products of individual accessions were scored for presence (1) or absence (0) of bands. Similarity matrices were developed and the accessions were grouped by cluster (UPGMA) and principal coordinate analysis. Analyses were conducted within ploidy level (2x = 18 and 4x = 36) and over ploidy levels. Each primer revealed polymorphic loci among accessions within species. Of 539 loci (bands) scored, 496 (92%) were polymorphic. Cynodon arcuatus was clearly separated from other species by numerous monomorphic bands. The strongest species similarities were between C. aethiopicus and C. arcuatus, C. transvaalensis and C. plectostachyus, and C. incompletus and C. nlemfuensis. Intraspecific variation was least for C. aethiopicus, C. arcuatus, and C. transvaalensis, and greatest for C. dactylon. Accessions of like taxonomic classification were generally clustered, except the cosmopolitan C. dactylon var. dactylon and C. dactylon var. afganicus. Within taxa, accessions differing in chromosome number clustered in all instances indicating the 2x and 4x forms to be closely related. Little, if any, relationship was found between relatedness as indicated by the DAF profiles and previous estimates of hybridization potential between the different taxa.     

三峡水库消落区不同生活史类型植物群落的空间分布格局

为探究三峡水库消落区不同生活史植物群落随海拔梯度及水库干流沿程的空间分布规律,于2017年8月至2017年9月对三峡水库干流消落区植被进行了调查。研究结果表明:(1)三峡水库消落区植被的植物物种丰富度随距大坝里程距离的缩短而呈现逐渐减小的趋势。(2)三峡水库消落区不同生活史类型植被群落盖度对水淹梯度胁迫的响应呈现相反的变化规律:随着消落区高程的升高,一年生植物对消落区植被覆盖度的贡献逐渐增加,而多年生植物对植被群落覆盖度的贡献逐渐降低。但是,在消落区的任一高程区域,多年生植物物种盖度均要大于一年生植物物种盖度。(3)采用TWINSPAN植被分类方法可对9个样地607个样方的三峡水库消落区植被划分为25个组,其中苍耳+狗牙根群落Ass.Xanthiumsibiricum+Cynodon dactylon(含213个样方)、狗牙根群落Ass.Cynodon dactylon(包含137个样方)、狗牙根+香附子群落Ass.Cynodon dactylon+Cyperus rotundus(含55个样方)、狗牙根+酸模叶蓼群落Ass.Cynodon dactylon+Polygonum lap...     

类芦和狗牙根内生固氮菌初步研究

为探索水土保持禾草的固氮能力,利用乙炔还原法(ARA)对类芦(Neyraudia reynaudiana)和狗牙根(Cynodon dactylon)植株内生固氮菌的固氮酶活性进行研究.结果表明:在类芦茎部和狗牙根叶片中存在高固氮酶活性的内生固氮菌群;这些菌群在无氮培养基上经划线分离纯化得到40个菌株,其中26株有微弱固氮酶活性,14株检测不到固氮酶活性;从类芦茎部和狗牙根叶片中筛选到的固氮菌群在兼性厌氧的环境中有较高的固氮酶活性,且在石蜡油密封条件下,两者的固氮酶活性均最高;在不改变自然界微生物之间的协同关系情况下,混合菌群均具有较高的固氮酶活性,而人为组配混合得到的菌群固氮酶活性较低. reynaudiana)和狗牙根(Cynodondxtylon)植株内生固氮菌的固氮酶活性进行研究.结果表明:在类芦茎部和狗牙根叶片中存在高固氮酶活性的内生固氮菌群;这些菌群在无氮培养基上经划线分离纯化得到40个菌株,其中26株有微弱固氮酶活性,14株检测不到固氮酶活性;从类芦茎部和狗牙根叶片中筛选到的固氮菌群在兼性厌氧的环境中有较高的固氮酶活性,且在石蜡油密封条件下,两者的固氮酶活性均最高;在不改变自然界微生物之间的协同关系 况下,混合菌群均具有较高的固氮酶     

Somatic embryogenesis and plant regeneration of turf-type bermudagrass: Effect of 6-benzyladenine in callus induction medium

In order to optimize tissue culture conditions for bermudagrass, an important warm-season turfgrass species, tissue culture responses of young inflorescences of a hybrid bermudagrass cultivar `Tifgreen' (Cynodon dactylon×Cynodon transvaalensis) and a common bermudagrass cultivar `Savannah' (Cynodon dactylon) were investigated. When cultured on Murashige and Skoog medium with 4.52 to 13.57 μM (1–3 mg l^-1) 2,4-D, young inflorescence segments yielded non-embryogenic calli which were unorganized and had loosely associated, long tubular cells on the surface. However, inclusion of 6-benzyladenine (BA) in callus induction medium at a level of 0.044 μM (0.01 mg l^-1) induced formation of a compact, nodular embryogenic structure on approximately 20% of the calli. Calli with such a compact embryogenic structure were highly regenerable. When young inflorescences smaller than 0.75 cm were cultured, the embryogenic structure yielded green plantlets with regeneration rates of 79.5% and 83.3%, respectively for the two cultivars. All 96 plants regenerated from calli induced in the BA-containing medium were green and morphologically normal. The embryogenic nature of the compact structure was confirmed by scanning electron microscopy. This revised version was published online in June 2006 with corrections to the Cover Date.     

Genomic constitution,allopolyploidy, and evolutionary proposal for Cynodon Rich. based on GISH

Protoplasma - Polyploidy is the main mechanism for chromosome number variation in Cynodon. Taxonomic boundaries are difficult to define and, although phylogenetic studies indicate that some species...     

Inflorescence diversification in the "finger millet clade" (Chloridoideae, Poaceae): a comparison of molecular phylogeny and developmental morphology

Within the Poaceae, inflorescence diversification and its bearing on phylogeny and evolution are exceedingly complex. We used phylogenetic information of the "finger millet clade," a group of grasses with digitate inflorescences, to study the inflorescence diversification. This clade appears monophyletic in the morphological and molecular phylogenetic analyses. Three well-supported clades are shown in our cpDNA-derived phylogeny, with clades I and III consisting of species of Chloris and Microchloa, respectively, and clade II including species of Cynodon, Dactyloctenium, and Eleusine. Variation appears at different times throughout development. Changes involving primordium number and arrangement occur very early, changes involving duration of primordium activity occur much later. Characters derived from the comparison of developmental sequences were optimized onto the most parsimonious tree. The developmental characters were congruent with the molecular phylogeny. Two developmental characters may not be homologous in the Chloris subclade and the Cynodon subclade.     

基于SRAP和TRAP标记的河北野生狗牙根种质遗传多样性分析

以SRAP和TRAP 2种标记技术对36份狗牙根材料的遗传多样性及亲缘关系进行了分析,其中包含34份河北省野生狗牙根种质资源。分别由238对SRAP和85对TRAP引物组合中筛选获得具有多态性的SRAP和TRAP引物组合各10对,PCR扩增总条带分别为186和161条,多态性条带156和132条,平均每对引物扩增出多态性条带各15.6和13.2条,多态性位点比率分别为83.4%和81.0%。2种标记合并进行聚类分析,所有供试的36份狗牙根材料遗传相似系数GS=0.519~0.983,平均为0.7。当GS=0.68时,可将36份供试材料分为4个类群。本研究结果表明河北野生狗牙根种质资源存在较丰富的遗传多样性,可为种质资源保护和选育优良狗牙根新品种提供科学依据。     

白蕊草组织培养和快速繁殖的研究

通过对白蕊草组织培养的培养基种类,激素配比,添加物汁液,碳源的研究,得出适合白蕊草侧芽分化生长的最佳培养基为MS＋6－BA2.0mg/L＋NAA0．5mg/L 狗牙根汁液。诱导愈伤组织以2,4－D浓度在0.5mg/L-2mg/L之间最佳。碳源以蔗糖,浓度3％最佳。生根实验表明：较低浓度的生长素不利于生根,最佳生根培养基为MS＋6－BA0.5mg/L NAA2mg/L 狗牙根汁液或MS＋6－BA0.5mg/L IBA2mg/L 狗牙根汁液。     

垃圾填埋场渗滤液尾水灌溉下百慕大草抗氧化系统的反应

通过盆栽试验,研究了渗滤液尾水灌溉下百慕大草的膜脂过氧化及酶促、非酶促抗氧化系统的反应.结果表明,低稀释比的渗滤液尾水(<25%)灌溉下,随着稀释比增大,百慕大草叶绿素a/b提高,丙二醛(MDA)、H₂O₂含量及膜透性降低,膜脂过氧化水平较轻;但中、高稀释比(>25%)下,随稀释比的增大则显示出一定的负效应,表现为叶绿素a/b降低,MDA、H₂O₂含量及膜透性提高,从而导致膜脂过氧化水平提高.非酶抗氧化剂抗坏血酸(AsA)、还原型谷胱甘肽(GSH)、类胡萝卜素(Car)含量的变化趋势相同,即低稀释比下含量升高,中高稀释比胁迫下明显降低.抗氧化酶中,超氧化物岐化酶(SOD)和过氧化物酶(POD)的活性变化同抗氧化剂变化趋势相似,但POD对胁迫的反应更敏感;而过氧化氢酶(CAT)活性变化趋势则先减弱后增强;MDA含量和抗氧化剂含量、抗氧化酶SOD、POD活性间的显著负相关,表明3种抗氧化剂和SOD、POD在防止百慕大草膜脂过氧化上可能起到更重要的作用.     

野生狗牙根种质遗传多样性的SRAP研究

采用SRAP分子标记技术, 对采自中国四川、重庆、贵州、西藏四省区的32份野生狗牙根(Cynodon dactylon)材料进行遗传多样性分析, 获得下述结果：(1)用14对引物组合共得到132条多态性条带, 平均每对引物扩增出9.4条多态带, 多态性位点百分率为79.8%, 材料间的遗传相似系数范围在0.591到0.957之间, 平均GS值为0.759, 这些结果说明, 供试野生狗牙根具有较为丰富的遗传多样性; (2)对所有材料进行聚类分析, 可聚为4类, 大部分来自相同或相似生态地理环境的材料聚为一类, 表明供试材料的聚类和其生态地理环境间有一定的相关性; (3)基于Shannon多样性指数估算了6个狗牙根生态地理类群内和类群间的遗传分化, 发现类群内遗传变异占总变异的65.56%, 而类群间遗传变异占总变异的34.44%; (4)对各生态地理类群基于Nei氏无偏估计的遗传一致度的聚类分析表明, 各生态地理类群间的遗传分化与其所处的生态地理环境具有一定的相关性。