Stolonifera Plants Research Articles

Cell selection to increase lawn grass resistance to lead pollution

Lead is one of the priority soil pollutants among heavy metals. To increase the species diversity of ecosystems, it is necessary to increase the resistance of plants to lead. The aim of the work was to obtain plants resistant to lead. The objects of our study were to lawn grasses. The effect of lead on the growth and regenerative ability of calli was determined. The results of this work showed that lead is less toxic to calli than copper. Biotechnological method for obtaining lead resistant plants has been developed. The effect of lead on the growth of regenerants and original plants was determined. Agrostis stolonifera plants that are obtained after cell selection have demonstrated a high degree of resistance to lead. Can the developed technology be used for other lawn grasses? We obtained lead resistant plants Festuca rubra. Therefore, using cell selection can increase the tolerance of lawn grasses to lead.

Plant clustering generates negative plant–soil feedback without changing the spatial distribution of soil fauna

Abstract. The spatial distribution of resources affects ecological processes at all levels of biological organization. However, it remains to be tested how the spatial configuration of belowground resources affects the community dynamics of soil organisms and resulting plant–soil feedbacks. We used Agrostis stolonifera plants in different spatial configurations in mesocosms to study the dispersal patterns of soil nematodes and rotifers. Plant–soil feedbacks were later assessed by re-sowing the mesocosms with Lolium perenne and Plantago lanceolata after removing all the initial A. stolonifera plants from the mesocosms. Bacterial-feeding nematodes and rotifers spread fast, whereas plant-feeding nematodes barely dispersed from the release sites. These spread patterns of nematodes and rotifers depended on the life-history traits and not on the spatial pattern of the plants. However, more clustered plants developed a higher total biomass and caused a reduced growth of the subsequent vegetation. Our results demonstrate that the mere spatial pattern of a single plant species can alter the strength of plant–soil feedbacks. This has important implications for understanding the impact of planting or replanting schemes and other changes in the spatial configuration of plants on long-term vegetation development and succession.

Leachates from plants recently infected by root-feeding nematodes cause increased biomass allocation to roots in neighbouring plants

Plants can adjust defence strategies in response to signals from neighbouring plants attacked by aboveground herbivores. Whether similar responses exist to belowground herbivory remains less studied, particularly regarding the spatiotemporal dynamics of such belowground signalling. We grew the grass Agrostis stolonifera with or without root-feeding nematodes (Meloidogyne minor). Leachates were extracted at different distances from these plants and at different times after inoculation. The leachates were applied to receiver A. stolonifera plants, of which root, shoot, and total biomass, root/shoot ratio, shoot height, shoot branch number, maximum rooting depth and root number were measured 3 weeks after leachate application. Receiver plants allocated significantly more biomass to roots when treated with leachates from nematode-inoculated plants at early infection stages. However, receiver plants’ root/shoot ratio was similar when receiving leachates collected at later stages from nematode-infected or control plants. Overall, early-collected leachates reduced growth of receiver plants significantly. Plants recently infected by root-feeding nematodes can thus induce increased root proliferation of neighbouring plants through root-derived compounds. Possible explanations for this response include a better tolerance of anticipated root damage by nematodes or the ability to grow roots away from the nematode-infected soil. Further investigations are still needed to identify the exact mechanisms.

Belowground plant-plant signaling of root infection by nematodes

Communication between plants mediated by herbivore-induced volatile organic compounds has been extensively studied aboveground. However, the role of root herbivory in belowground plant-plant communication is much less understood. We here investigated whether root herbivores can trigger plant roots to emit warning signals to neighbouring plants that are not yet in direct contact with them.We used a split-root system and infected half of the roots of Agrostis stolonifera plants with root-knot nematodes (Meloidogyne minor) and left the other half uninfected. As a control, we grew plants without nematodes in separate pots. Leachates from each split-root soil compartment and from soils with control plants were applied to separate pots with A. stolonifera plants, of which biomass allocation and morphological traits were measured one month after leachate addition.Plants receiving leachates from the soil with the nematode-free roots of the nematode-infected plants showed a significantly larger total biomass, more root branches, and deeper rooting than plants receiving leachates from the soil with the nematode-infected roots or from soil with control plants. Plants were taller and the root/shoot ratio was higher in plants receiving leachates from soil with the nematode-free roots than in plants receiving leachates from soil with nematode-infected roots. Shoot tiller number was higher in plants receiving leachates from either root compartment of the nematode-infected plants than in plants receiving control leachates.Our results suggest that an overcompensation response was triggered by systemically induced root-derived compounds from nematode-free roots of a plant locally infected with root-feeding nematodes. Signals from directly attacked roots of the same nematode-infected plant only caused receiver plants to develop more shoot tillers, possibly for future stolon development to grow away from the infected area. This may indicate an anticipatory tolerance response to root feeders that are still distant and an additional generalized escape response to root feeding.

Phytostabilization as a phytoremediation strategy for mitigating water pollutants by the floating macrophyte Ludwigia stolonifera (Guill. & Perr.) P.H. Raven

The present study evaluated the phytoremediation potential of the floating macrophyte Ludwigia stolonifera for removing trace metals from contaminated water bodies. Forty quadrats, distributed equally in eight sites (six polluted two unpolluted sites) were selected seasonally for water, sediment and plant investigations. The leaf area, fresh and dry biomass, chlorophyll b and carotenoids contents of L. stolonifera were significantly reduced in polluted sites. L. stolonifera plants accumulated concentrations of the investigated trace metals in their roots higher than the shoots. The roots contributed to the highest concentrations of Al and Cu during spring; Fe, Mn and Ni during summer; Cd and Zn during autumn; and Cr and Pb during winter. Compared to the unpolluted sites, the below- and above-ground parts from the polluted sites accumulated higher concentrations of most investigated trace metals, except Fe. The below-ground parts of L. stolonifera had high seasonal potential for seasonal accumulation of Cd, Cu, Ni, Zn and Pb with a bioaccumulation factor that exceeded 1, the translocation factor of the investigated metals was <1. Therefore, the study species is suitable for metals phytostabilization and thus can be considered a potential phytoremediator of these metals.

追肥对白芹吸收积累铅的影响

为研究不同追肥对白芹吸收积累铅的影响及探索白芹铅污染原因及控制技术，本文在白芹核心产地选择三个试验区设置了追肥试验，并对土壤、灌溉水、肥料和白芹产品进行了取样测定。样品测定结果表明，三个试验区都存在白芹样品及灌溉水样品铅含量超标情况，在二个试验区存在土壤样品铅含量超标情况，白芹铅含量超标与灌溉水铅含量高度相关，与土壤铅含量有一定关系，但与肥料中铅含量的关系不明显。白芹铅含量超标的主要来源是灌溉水中的铅，另一个来源可能是土壤中的铅。追肥研究表明，追施磷酸二铵能大幅度降低白芹铅含量，对白芹产量没有显著影响。因此，在白芹生产中，应降低灌溉水的铅浓度或选用更清洁的水源，选用磷酸二铵作为追肥品种。 In order to study the effects of different fertilizations on the accumulation of lead (Pb) in Oenanthe stolonifera D.C., and to investigate the pollution sources of Pb in Oenanthe stolonifera and the pre-venting technologies, three sampling areas were selected in the production region. In the areas, the soils, irrigation water, fertilizers and Oenanthe stolonifera plants were sampled to test Pb concentrations. The results showed that Pb concentrations exceeded the maximum allowable concentrations (MAC, according to the Chinese Standards) in some Oenanthe stolonifera and irri-gation water samples in three areas, and in some soil samples in two areas. Pb accumulations in Oenanthe stolonifera samples were related highly to Pb concentrations of irrigation water samples, and somewhat with Pb concentrations of soil samples, but had no evident relation with Pb con-centrations of the fertilizers. Therefore, the Pb in irrigation water was the main source of Pb pol-lution in Oenanthe stolonifera, and the Pb in soils might be another pollution source. Application of the fertilizer diammonium phosphate reduced Pb concentration of Oenanthe stolonifera greatly, and had no significant influence on the yield of Oenanthe stolonifera. It can be concluded that Pb concentration in the irrigation water should be reduced, in the production of Oenanthe stolonifera, or the cleaner irrigation water ought to be selected. Diammonium phosphate is the suitable ferti-lizer.

Identification of Waitea circinata as a Pathogen of the Moss Bryum argenteum var. argenteum on a Golf Course Fairway.

Waitea circinata Warcup and Talbot (also referred to as W. circinata var. circinata) is an important fungal pathogen of amenity turfgrasses and is especially problematic on Poa annua in putting greens in the late spring or early summer. The pathogen was first identified in 2005 from Japan and has since been seen widely throughout the United States (1,2). On occasion, the pathogen has been observed attacking creeping bentgrass (Agrostis stolonifera) but is typically less virulent. Disease symptoms include prominent yellow rings appearing throughout established turf and moderate leaf necrosis. In the summer of 2012, moss from a section of fairway on a golf course in Edwards, CO was observed to be rapidly killed by a fungal pathogen producing copious amounts of aerial mycelium and appearing similar to Waitea microscopically. Aerial mycelium was transferred to acidified potato dextrose agar (PDA) (1 ml lactic/L). After 1 day at 25°C, mycelia were transferred to PDA. After 2 weeks, plates were covered with white aerial mycelium and separate, spherical, 0.5-mm diameter, salmon-colored sclerotia, which turned dark brown within a few days and were produced submerged throughout the media. Spores were never produced and right-angled branching of mycelia, characteristic of Waitea, was observed in mature cultures. Mycelial plugs were incubated in nutrient broth and DNA was extracted using a MoBio Power Plant DNA extraction kit. Amplification of ribosomal ITS sequences with ITS4 and ITS5 resulted in a 100% identity match with GenBank sequence HM807352, W. circinata var. circinta (3). To demonstrate pathogenicity on Bryum argenteum, unaffected moss from the submitted sample (identified as B. argenteum var. argenteum via 100% sequence identity with the published GenBank sequence GU907062) was removed from the originally submitted sample and placed in separate growth chambers at 95% humidity and 21, 26, and 31°C. An additional experiment employed local B. agenteum plants collected from the URI Kingston, RI campus. Agar plugs from the isolated W. circinata were placed on top of the moss and within 2 days the fungus had caused complete mortality at all three temperatures. The experiment was also undertaken using the same environmental conditions with 5-week-old annual bluegrass (P. annua) and creeping bentgrass cv. A4 grown from seed. Plants were inoculated with infected rye grains at 31, 26, and 21°C. After 1 week, the P. annua plants showed significant mortality at 26 and 31°C with little infection at 21°C and the A. stolonifera plants showed moderate mortality at 26°C and little infection at the other two temperatures. All experiments utilized an additional uninoculated control treatment that showed no moss/turf necrosis or mortality. Experiments were all repeated once and used three replicates per experiment. While moss is not intentionally cultivated on golf courses, it does occur with regularity and often presents itself as a difficult pest to manage. This particular isolate of W. circinata has identical ribosomal and physiological characteristics of the reported P. annua pathogen but can attack one moss species and may be a possible candidate for selective biological control of moss in golf course settings. It is unclear how widespread moss pathogenicity is within W. circinata.

Establishment of transgenic herbicide‐resistant creeping bentgrass (Agrostis stolonifera L.) in nonagronomic habitats

Concerns about genetically modified (GM) crops include transgene flow to compatible wild species and unintended ecological consequences of potential transgene introgression. However, there has been little empirical documentation of establishment and distribution of transgenic plants in wild populations. We present herein the first evidence for escape of transgenes into wild plant populations within the USA; glyphosate-resistant creeping bentgrass (Agrostis stolonifera L.) plants expressing CP4 EPSPS transgenes were found outside of cultivation area in central Oregon. Resident populations of three compatible Agrostis species were sampled in nonagronomic habitats outside the Oregon Department of Agriculture control area designated for test production of glyphosate-resistant creeping bentgrass. CP4 EPSPS protein and the corresponding transgene were found in nine A. stolonifera plants screened from 20,400 samples (0.04 +/- 0.01% SE). CP4 EPSPS-positive plants were located predominantly in mesic habitats downwind and up to 3.8 km beyond the control area perimeter; two plants were found within the USDA Crooked River National Grassland. Spatial distribution and parentage of transgenic plants (as confirmed by analyses of nuclear ITS and chloroplast matK gene trees) suggest that establishment resulted from both pollen-mediated intraspecific hybridizations and from crop seed dispersal. These results demonstrate that transgene flow from short-term production can result in establishment of transgenic plants at multi-kilometre distances from GM source fields or plants. Selective pressure from direct application or drift of glyphosate herbicide could enhance introgression of CP4 EPSPS transgenes and additional establishment. Obligatory outcrossing and vegetative spread could further contribute to persistence of CP4 EPSPS transgenes in wild Agrostis populations, both in the presence or absence of herbicide selection.

First Report of Typhula Blight on Agrostis stolonifera and Poa annua in Italy.

During January 2002, Agrostis stolonifera and Poa annua turfgrasses on a golf course in Avigliana (northern Italy) exhibited 10- to 45-cm-diameter circular patches when the snow melted from the greens, tees, and fairways. Many patches coalesced to form large areas of strawcolored blighted turfgrass. At the patch margin, infected plants were covered with white-to-gray mycelium. Plants within patches were matted and appeared slimy with mycelium and sclerotia that were light pink, irregularly shaped, and less than 5 mm in diameter. Isolation from infected leaves on potato dextrose agar, supplemented with 100 mg/l of streptomycin sulfate, consistently yielded a fungus with mycelial, sclerotia, and cultural characteristics of Typhula incarnata (1). Pathogenicity tests were performed by spraying a suspension of mycelium and sclerotia, prepared by chopping mycelium and sclerotia produced in potato dextrose broth, onto 8-week-old A. stolonifera plants grown in plastic trays (45 × 30 cm). Trays were maintained at 0°C for 8 weeks in the dark. Blight symptoms developed on inoculated plants after 6 weeks. Non-inoculated plants remained healthy. The pathogen was reisolated from inoculated plants, and the pathogenicity test was repeated once. Typhula blight incited by T. incarnata was reported in Scandinavian countries and in several European countries including Holland, Germany, Austria, and Switzerland (1). To our knowledge, this is the first report of Typhula blight on turfgrass in Italy. Reference: (1) J. D. Smith et al. 1989. Fungal Diseases of Amenity Turf Grasses. E & FN Spong Ltd, London.

Shifts in the microbial community in rhizosphere and non-rhizosphere soils during the growth of Agrostis stolonifera

An investigation was conducted into the use of phospholipid fatty acid (PLFA) profiles to follow temporal shifts in microbial community structure. A laminar pot was designed to allow the harvest of an intact layer of rhizosphere soil 0–2 mm from plant roots without the removal of the root material itself. Agrostis stolonifera plants were grown under controlled conditions in environmental chambers for 70, 90, 120 and 160 days. A subset of pots was fertilised with N/P/K after 100 days. Over the 90 days between the first and last harvests microbial biomass declined by 20%. At 70 days respiration was approximately 50% higher in the rhizosphere compared to the bulk soil. This difference had declined to <10% by the end of the experiment. PLFA analysis showed significant changes in microbial community structure with time. In particular, the unsaturated fatty acids commonly found in Gram-negative bacteria and fungi increased with age. Principal component analysis (PCA) of fatty acid data showed: separation of bulk and rhizosphere soils from 90 days onwards, and; fertiliser addition and rhizosphere development produced similar shifts in community structure.

Transgenic plants of Lolium multiflorum, Lolium perenne, Festuca arundinacea and Agrostis stolonifera by silicon carbide fibre-mediated transformation of cell suspension cultures

Seven Lolium multiflorum, one Lolium perenne, 12 Festuca arundinacea and six Agrostis stolonifera plants were regenerated following transformation with a hygromycin resistance gene and hygromycin selection, from cell suspension colonies treated with silicon–carbide whiskers. Transformation was confirmed by PCR and Southern blotting; the latter also showed that six of the L. multiflorum plants were independent transformants (insufficient molecular evidence was obtained for the seventh), nine of the 12 F. arundinacea plants were independent transformants, but that all the A. stolonifera plants were derived from a single transformation event. Most plants tested contained fewer than five integrated transgene copies. Transgene expression was confirmed by reverse transcriptase-PCR (RT-PCR). Of the one A. stolonifera and three L. multiflorum transformants regenerated after co-transformation with both the hygromycin resistance gene and the β-glucuronidase (gusA) gene, none were found to express GUS activity. L. multiflorum regenerants from older (14–16 week old) cell suspensions showed loss of female fertility, but analysis of the progeny from three plants showed that the transgenes were being inherited as a single dominant allele with a high frequency of transmission of hygromycin resistance.

A comparison of stable caesium uptake by six grass species of contrasting growth strategy

Six plant species in the family Gramineae were used to investigate the relationship between Cs uptake, nutrient regime and plant growth strategy sensu Grime (1979: Plant Growth Strategies and Vegetation Processes, John Wiley). The roots of 66 day old Elymus repens (L.) Gould., Bromus sterilis L., Agrostis stolonifera L., Anthoxanthum odoratum L., Festuca ovina L. and Nardus stricta L. plants grown in acid-washed sand at high and low nutrient levels were exposed to a 96 h pulse of stable Cs at 0.05 m m, 0.15 m m, 0.3 m m, 1.0 m m and 3.0 m m concentrations. Different nutrient regimes induced large differences in dry wt in E. repens, B. sterilis and A. stolonifera plants but only small differences in N. stricta and F. ovina plants. At high nutrient concentrations, A. stolonifera, A. odoratum, F. ovina and N. stricta shoots showed significantly greater increases in internal Cs concentration with rising external Cs concentrations than did E. repens and B. sterilis shoots. The relationship between increases in shoot and external Cs concentrations was statistically indistinguishable between species in plants grown at the low nutrient concentration. These patterns of Cs uptake ensured that with long-term high K concentrations the more competitive plants ( E. repens and B. sterilis) accumulated higher concentrations of Cs from low external concentrations than did non-competitive plants or competitive plants grown at low nutrient levels. It is suggested that the relationship between plant growth strategy sensu Grime (1979) and Cs accumulation patterns may help to explain the different concentrations to which species accumulate radiocaesium from the soil.