Rapd fingerprinting of diploid Lolium perenne × hexaploid Festuca arundinacea hybrid genomes

We tested the application of RAPD technology for identification of hybrid genomes originated from a maternal clone of Lolium perenne L. (2n = 2x = 14) bearing cytoplasmic male sterility, which was pollinated separately by five clones of Festuca arundinacea Schreb. cv. Barocco (2n = 6x = 42). Six classes of RAPD markers were recognized, specific to: 1) Festuca genome and inherited into F1 hybrid genomes, 2) Lolium genome inherited into F1 hybrid genomes, 3) Lolium-specific bands not found in F1 progeny, 4) Festuca-specific bands not found in F1 progeny, 5) new bands found only in F1 hybrid profiles, 6) bands common to all parental and F1 hybrid genotypes. RAPD data were shown to have full potential a) to serve as an unequivocal proof of genome recombination in perennial ryegrass × tall fescue hybrids, b) to identify hybrid genomes, c) to reveal phenetic relationships of the accessions from crossing families, d) to enhance, by fingerprinting, the selection of superior hybrid material for further breeding. RAPD data were found to be consistent with the festucoid phenotype of F1 hybrids. This revised version was published online in July 2006 with corrections to the Cover Date.     

水土保持型牧草苇状羊茅(Festuca arundinacea Schreb)节肢动物群落结构

对水土保持型牧草苇状羊茅节肢动物群落的系统调查,根据节肢动物群落中物种的营养和取食关系将总群落划分为天敌亚群落和非天敌亚群落(含害虫和中性昆虫),以调查到的节肢动物种类、个体数量结合各群落生态学指标分析总群落及亚群落的结构组成.结果表明:共查得苇状羊茅节肢动物139种分属68科;非天敌亚群落为总群落主要成分,相对多度为0.7661,其中优势种为同翅目昆虫;天敌亚群落相对多度为0.2339;优势种为蜘蛛类天敌.优势集中性和优势度分析表明非天敌亚群落>总群落>天敌亚群落;均匀度指数除5、9月份外,均表现为天敌亚群落>总群落>非天敌亚群落;多样性指数除4、5月份外,均表现为总群落>非天敌亚群落>天敌亚群落.     

盐胁迫对高羊茅(Festuca arundinacea)幼苗生长和离子分布的影响

盐胁迫环境抑制植物的生长，影响植物组织的离子分布，不同的盐分组成对植物的抑制伤害存在差异，为了研究上海市临港新城滨海盐渍土的生态恢复和重建，模拟该地区的盐分组成，进行了高羊茅（Festuca arundinacea）幼苗的盐胁迫试验。高羊茅种子在非盐胁迫条件下萌发，出苗5d后，进行了不同浓度NaCl：0、50、100、150、200、300、400mmol／L处理，15d后测定生长情况、组织含水量和Na^＋、K^＋、Ca^2＋、Mg^2＋等离子含量。研究结果表明：盐分对高羊茅幼苗的抑制作用随NaCl浓度增加而加剧，低盐胁迫环境下，幼苗地上部分和根系的鲜重、干重和含水量都与对照没有显著性差异，但是高盐环境严重影响了高羊茅幼苗的生长，而且对地上部分的抑制作用大于根部；盐胁迫影响植物组织的离子分布，Na^＋浓度持续增加，Ca^2＋和K^＋浓度下降，Mg^2＋含量的影响不大；各组织中K／Na、Ca／Na和Mg／Na随盐胁迫增加而下降。     

Effect of 2,4-D on Seedling Physiology and Cytogenetical Studies in Triticum aestivum and Phalaris minor (Gramineae)

Effects of 2, 4 -D on seedling growth and chromosomal abnormalities were studied in Triticum aestivum and Phalaris minor. Seeds were soaked at different concentrations of 2,4 -D （0.01%, 0.1%, 1.0% ） for 4, 8, 12 and 16 hours. 2,4-D suppressed the germination more severely in P. minor than in T. aestivum. Shoot and root length was retarded with the increase of concentration and time of treatment in both species. Generally radical was more negatively affected than coleoptile and emergence of radical was not observed at 1.0% concentration at 8, 12, and 16 hours of treatment in T. aestivum while in P. minor there was a total lack of radical emergence at 1.0% concentration for all durations of treatment. Stiff and curled roots and undifferentiated callus like scutellar tissues were observed in T. aestivum, while in P. minor the coleoptile obtained was lean, pale green in colour and was lying flat on filter paper. Mitotic index decreased, while chromosomal abnormalities, bridges and laggards were increased with the increase of concentration and soaking time however, laggards were not observed in T. aestivum. Clumping and chain formation of chromosomes at metaphase was also noticed in P. minor.     

Effect of 2,4-D on Seedling Physiology and Cytogenetical Studies in Triticum aextivum and Phalaris minor(Gramineae)

Effects of 2, 4 -D on seedling growth and chromosomal abnormalities were studied in Triticum aestivum and Phalaris minor. Seeds were soaked at different concentrations of 2, 4 -D (0.01%, 0.1%, 1.0%) for 4, 8, 12 and 16 hours. 2, 4 -D suppressed the germination more severely in P. minor than in T. aestivum. Shoot and root length was retarded with the increase of concentration and time of treatment in both species. Generally radical was more negatively affected than coleoptile and emergence of radical was not observed at 1.0% concentration at 8, 12, and 16 hours of treatment in T. aestivum while in P. minor there was a total lack of radical emergence at 1.0% concentration for all durations of treatment. Stiff and curled roots and undifferentiated callus like scutellar tissues were observed in T. aestivum, while in P. minor the coleoptile obtained was lean, pale green in colour and was lying flat on filter paper. Mitotic index decreased, while chromosomal abnormalities, bridges and laggards were increased with the increase of concentration and soaking time however, laggards were not observed in T. aestivum. Clumping and chain formation of chromosomes at metaphase was also noticed in P. minor.     

How does the Fungal Endophyte Neotyphodium coenophialum Affect Tall Fescue (Festuca arundinacea) Rhizodeposition and Soil Microorganisms?

The goal of our study was to investigate the impact of fungal endophytes in tall fescue (Festuca arundinacea) on rhizodeposition and in turn, the soil microbial community. Sand-based, aseptic microlysimeter units were constructed for the collection of rhizodeposit solutions for chemical analyses from the roots of endophyte-free (E−) and endophyte-infected (E+) tall fescue plants. E+ plants were infected with Neotyphodium coenophialum, the most common endophyte found in tall fescue. Rhizodeposit solutions collected over nine weeks from E+ grass contained more organic carbon and carbohydrates than E−. These solutions were allowed to percolate through columns of plant-free soils to assess the response of the soil microbial communities. Soils to which solutions from E+ grass were applied had significantly higher respiration rates than those receiving solutions from E− grass, suggesting that microbial activity was stimulated by changes in the rhizodeposits. Culture-based assays of the soil microbial community (plate counts and community-level physiological profiling) suggest that the basic structure of the microbial community was not affected by application of rhizodeposit solutions from E+ plants as compared to E−. Our results indicate that the presence of a fungal endophyte may enhance rhizodeposition by tall fescue and could consequently influence microbial mineralization processes in the soil. In grasslands where nutrients may be limiting, hosting a fungal endophyte has the potential to enhance plant nutrient supply indirectly via a stimulatory effect on the soil microbial biomass. Megan M. Van Hecke and Amy M. Treonis - Both authors contributed equally to this work.     

Does morphological plasticity of the <Emphasis Type="Italic">Phalaris arundinacea</Emphasis> canopy increase invasiveness?

Morphological plasticity could facilitate invasions of wetland plants into areas that experience increased durations of flooding and eutrophication. We explored canopy plasticity of Phalaris arundinacea, an aggressive invader of wetlands, as it differentially invaded wet prairie mesocosms under 3 flooding durations and 3 levels of nutrient addition. Phalaris grew as a sward with intermittent and early-season flooding but shifted to tussocks under constant flooding. These two growth forms differed by >20% in several canopy ratios. Clones that formed tussocks produced 45% more shoots per unit biomass (P = 0.007) and a 25% higher ratio of total shoot length to biomass (P = 0.04). Lighter-weight shoots supported 33% fewer leaves and, consequently, had 35% less leaf area per shoot height (P < 0.002). Tussocks developed a continuous mat of adventitious roots, with root mats reaching 20.9 ± 0.6 cm in diameter and 4.7 ± 0.3 cm in height over two growing seasons. While forming tussocks, Phalaris tolerated longer durations of flooding and more than doubled its aboveground biomass. Invasions occurred rapidly, with Phalaris exceeding 75% canopy cover and accounting for 66% of the total aboveground biomass under constant flooding. Early-season flooding increased the lateral spread of individual shoots. High nutrient addition produced shoots that were 27% taller and 50% heavier (P < 0.02), with 81% more leaf area (P < 0.0003) than shoots that received no nutrients. Consequently, under early-season flooding with high nutrient additions, Phalaris was primed to invade, nearly doubling its proportion of the total aboveground biomass and exceeding 50% canopy cover during year two.     

热锻炼对高羊茅(Festuca arundinacea)和多年生黑麦草(Lolium perenne)抗高温能力的影响

夏季高温胁迫已成为限制冷季型草坪草生长和发育的一个主要问题.以两种耐热性不同的冷季型草坪草高羊茅和多年生黑麦草(前者较耐热)为材料,经过3d 30℃的热锻炼预处理后,分别在38、42、46℃的高温下处理14h.在这些高温条件下,研究了经过热锻炼预处理的高羊茅和多年生黑麦草叶片膜脂过氧化、抗氧化剂含量以及叶绿体超微结构的变化.结果表明:(1)热锻炼提高了高羊茅和多年生黑麦草的耐热性,显著缓减了高温条件下两种草坪草叶片膜脂过氧化程度的加剧,降低了叶片过氧化氢(H2O2)和超氧阴离子(O2)的产生速率.(2)高温条件下,热锻炼使高羊茅和多年生黑麦草叶片中抗氧化剂抗坏血酸(AsA)和谷胱甘肽(GSH)的含量下降程度有所缓减.(3)热锻炼减轻了高温胁迫对高羊茅和多年生黑麦草叶片叶绿体超微结构的损伤.这些结果说明热锻炼能够减轻高温对草坪草叶绿体的伤害可能与其在高温胁迫下和对照相比具有较高的抗氧化剂含量有关,这也可能是冷季型草坪草对高温的适应机制之一.     

Screening for stable transformants and stability of β-glucuronidase gene expression in suspension cultured cells of tall fescue (Festuca arundinacea)

Summary By screening cell colonies derived from protoplasts of tall fescue (Festuca arundinacea), transformed with a rice actin-1-promoter-ß-glucuronidase gene construct, several ß-glucuronidase positive callus clones were obtained. Two callus clones with different GUS expression were derived from these. One was light blue after X-gluc staining, and expression of the ß-glucuronidase gene was stable over repeated subculture, while another stained intensely blue, and expression of the ß-glucuronidase gene was unstable. Southern blot analysis showed that only one copy of the ß-glucuronidase gene was integrated into the genome, and that these two clones appeared to have the same integration pattern. Treatment with 5-azacytidine maintained GUS expression in the unstable line but had no effect on reactivating expression of the GUS gene after expression had been lost. Following the screening procedure the callus clones would only regenerate albino plants.Abbreviations X-gluc 5-bromo-4-chloro-3-indolylglucuronide - GUS ß-glucuronidase - CaMV cauliflower mosaic virus - PEG polyethylene glycol - AZC 5-azacytidine - SDS sodium dodecyl sulphate - UV ultraviolet - EDTA ethylenediaminetetra-acetic acid disodium salt - SSPE salt-sodium-phosphate-EDTA - SSC standard saline citrate - hpt hygromycin phosphotransferase     

Does host adaptation of Tetranychus urticae populations in clementine orchards with a Festuca arundinacea cover contribute to a better natural regulation of this pest mite?

Tetranychus urticae Koch (Acari: Tetranychidae) is a key pest of clementine mandarins, Citrus clementina Tanaka (Rutaceae), in Spain. This mite is highly polyphagous and can be easily found in clementine orchards, both in the trees and in the associated flora. In a previous study we found that the use of a cover of Festuca arundinacea Schreber (Poaceae) offered a better regulation of T. urticae populations than either bare soil or the traditional wild cover, which included a mix of weed species. We hypothesized that the selection of two host races of T. urticae, specialized in F. arundinacea and C. clementina, could partly explain the results obtained (bottom‐up regulation). Reciprocal transplant experiments show that sympatric deme × host combinations had higher mean fitness values than the allopatric combinations in clementine, but not in F. arundinacea, for most of the fitness parameters evaluated in our study. Because local adaptation implies mean deme fitness to be systematically higher for the sympatric deme × habitat combinations than for the allopatric ones, these results can be taken as indicative of occurrence of local adaptation in T. urticae. Molecular genetic analyses with microsatellite markers support this conclusion and indicate that local adaptation of T. urticae found in our system may indeed contribute to a better natural regulation of this mite.     

Root and tuber phytoliths and starch grains document manioc (Manihot esculenta) arrowroot (Maranta arundinacea) and llerén (Calathea sp.) at the real alto site Ecuador

Although roots and tubers are dietary staples in many parts of the world, their use is difficult to document archaeo logically because their organic remains are often poorly preserved in archaeological sedi ments. Here we describe the first diagnostic phytoliths from the underground storage organs of the important New World agricultural crops manioc or yuca(Manihot esculenta Crantz), arrowroot(Maranta arundinacea L.), and llerén(Calathea allouia [Aubl.] Lindl.) and demonstrate their usefulness for identifying prehistoric root and tuber processing with a study of stone artifacts from a Valdivia 3 (2800–2400 B.C., calibrated) household at Real Alto, Ecuador. Gelatinized starch (heat-altered) and unaltered starch from maize (Zea mays L.), arrowroot, and manioc were also found on these stone tools. Our data document early evidence for manioc in Ecuador’s coastal lowlands. In combination, these phytoliths and starch residues provide evidence that both raw and cooked foods were processed in this early mixed agricultural economy.