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1.
Int J Syst Evol Microbiol ; 70(2): 1086-1092, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31751201

RESUMO

Six polymorphic yeast strains with strong antifungal activities isolated from dicot plants in an alkaline-lake desert region were subjected to taxonomic examination. The phylogenetic trees reconstructed by using neighbour-joining, maximum-likelihood and Bayesian methods from concatenated D1/D2 and ITS-5.8S-ITS2 sequences revealed phylogenetic affinity to Ustilaginaceae, but the large phylogenetic distance separating the isolates from the most closely related groups of species indicates that they represent a separate species. The sequences of the genes coding for the LSU rDNA, act1, rpb2 and a protein of unknown function corroborate this position. The isolates can easily be distinguished from their closest relatives by physiological tests (utilisation of carbon and nitrogen sources). Based on these results, a new species, Mycosarcoma aegyptiacum sp. nov., is proposed to accommodate the isolates. All isolates are polymorphic. Transitions between budding-yeast and pseudohyphal morphologies which take place during colony formation result in morphologically different colony sectors and invasive growth into the medium. Neither sexual mating nor sporulation was observed in cultures growing on laboratory media.


Assuntos
Filogenia , Rudbeckia/microbiologia , Ustilaginales/classificação , Teorema de Bayes , DNA Fúngico/genética , DNA Ribossômico/genética , DNA Espaçador Ribossômico/genética , Egito , Lagos , Técnicas de Tipagem Micológica , Folhas de Planta/microbiologia , Análise de Sequência de DNA , Ustilaginales/isolamento & purificação , Leveduras/classificação , Leveduras/isolamento & purificação
2.
Sci Total Environ ; 610-611: 591-601, 2018 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-28822927

RESUMO

Cutleaf coneflower (Rudbeckia laciniata L. var. digitata) is native to Great Smoky Mountains National Park (GRSM) and an ozone bioindicator species. Variety ampla, whose ozone sensitivity is less well known, is native to Rocky Mountain National Park (ROMO). In the early 2000s, researchers found putative ozone symptoms on var. ampla and rhizomes were sent to Appalachian State University to verify that the symptoms were the result of ozone exposure. In 2011, potted plants were exposed to ambient ozone from May to August. These same plants were grown in open-top chambers (OTCs) in 2012 and 2013, and exposed to charcoal-filtered (CF), non-filtered (NF), elevated ozone (EO), NF+50ppb in 2012 for 47days and NF+30/NF+50ppb ozone in 2013 for 36 and 36days, respectively. Ozone symptoms similar to those found in ROMO (blue-black adaxial stippling) were reproduced both in ambient air and in the OTCs. Both varieties exhibited foliar injury in the OTCs in an exposure-dependent manner, verifying that symptoms resulted from ozone exposure. In two of the three study years, var. digitata appeared more sensitive than var. ampla. Exposure to EO caused reductions in ambient photosynthetic rate (A) and stomatal conductance (gs) for both varieties. Light response curves indicated that ozone reduced A, gs, and the apparent quantum yield while it increased the light compensation point. In CF air, var. ampla had higher light saturated A (18.2±1.04 vs 11.6±0.37µmolm-2s-1), higher light saturation (1833±166.7 vs 1108±141.7µmolm-2s-1), and lower Ci/Ca ratio (0.67±0.01 vs 0.77±0.01) than var. digitata. Coneflowers in both Parks are adversely affected by exposure to ambient ozone and if ozone concentrations increase in the Rocky Mountains, greater amounts of injury on var. ampla can be expected.


Assuntos
Poluentes Atmosféricos/efeitos adversos , Ozônio/efeitos adversos , Rudbeckia/fisiologia , Região dos Apalaches , Parques Recreativos , Fotossíntese , Folhas de Planta , Estômatos de Plantas , Rudbeckia/efeitos dos fármacos , Espécies Sentinelas/fisiologia
3.
Virus Res ; 241: 62-67, 2017 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-28559100

RESUMO

A disease of Rudbeckia hirta (Black-eyed Susan), characterized by severe flower deformation, was observed in Minnesota during 2010-2016. A previously undescribed virus species, named Rudbeckia flower distortion virus (RuFDV, family Caulimoviridae, genus unassigned), was determined to be the causal agent of the disease. Symptoms induced by RuFDV infection resemble those characteristic of phytoplasma-induced diseases, but no phytoplasmas were detected in RuFDV-infected R. hirta. The virus, and the disease were transmitted readily by mechanical inoculation and by the aphid Myzus persicae, but only to R. hirta. Virions of RuFDV are icosahedral, 42-45nm in diameter, and contain a circular 8222bp dsDNA genome containing seven open reading frames (ORFs). The ORFs 2-6 have 28-52% amino acid sequence identity to the movement protein (MP), coat protein (CP), aspartic protease (AP), reverse transcriptase (RT) and RNase H, and translational transactivator (TA) domains of known caulimoviruses. The two remaining ORFs (1 and 7) have no significant amino acid sequence similarity to known viruses. Although the RuFDV ORF 6 is significantly truncated relative to those of other known caulimoviruses, neither this nor the concomitant absence of characteristic virus-encoded cytoplasmic inclusion bodies appears to adversely affect aphid transmission of this virus. Phylogenetic analysis based on the sequence of the RT region revealed no close relationship to known members of the family Caulimoviridae. Based on sequence similarity, genome organization and phylogenetic relatedness, RuFDV appears to be distinct from any currently recognized taxonomic grouping in the family Caulimoviridae.


Assuntos
Caulimoviridae/classificação , Caulimoviridae/genética , Flores/virologia , Doenças das Plantas/virologia , Rudbeckia/virologia , Sequência de Aminoácidos , Animais , Afídeos/virologia , Ácido Aspártico Proteases/genética , Proteínas do Capsídeo/genética , Insetos Vetores/virologia , Proteínas do Movimento Viral em Plantas/genética , DNA Polimerase Dirigida por RNA/genética , Ribonuclease H/genética , Homologia de Sequência de Aminoácidos
4.
Mycorrhiza ; 27(2): 83-94, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27581153

RESUMO

While a number of recent studies have revealed that arbuscular mycorrhizal fungi (AMF) can mediate invasive plant success, the influence of these symbionts on the most successful and high-impact invaders is largely unexplored. Two perennial herbs of this category of invasive plants, Rudbeckia laciniata and Solidago gigantea (Asteraceae), were thus tested in a pot experiment to determine whether AMF influence their growth, the concentration of phosphorus in biomass, and photosynthesis. The following treatments, including three common AMF species, were prepared on soils representative of two habitats that are frequently invaded by both plants, namely fallow and river valley: (1) control-soil without AMF, (2) Rhizophagus irregularis, (3) Funneliformis mosseae, and (4) Claroideoglomus claroideum. The invaders were strongly dependent on AMF for their growth. The mycorrhizal dependency of R. laciniata was 88 and 63 % and of S. gigantea 90 and 82 % for valley and fallow soils, respectively. The fungi also increased P concentration in their biomass. However, we found different effects of the fungal species in the stimulation of plant growth and P acquisition, with R. irregularis and C. claroideum being the most and least effective symbionts, respectively. None of AMF species had an impact on the photosynthetic performance indexes of both plants. Our findings indicate that AMF have a direct effect on the early stages of R. laciniata and S. gigantea growth. The magnitude of the response of both plant species to AMF was dependent on the fungal and soil identities. Therefore, the presence of particular AMF species in a site may determine the success of their invasion.


Assuntos
Glomeromycota/fisiologia , Espécies Introduzidas , Micorrizas/fisiologia , Fósforo/metabolismo , Rudbeckia/microbiologia , Solidago/microbiologia , Raízes de Plantas , Rudbeckia/crescimento & desenvolvimento , Rudbeckia/metabolismo , Solidago/crescimento & desenvolvimento , Solidago/metabolismo
5.
Sci Total Environ ; 574: 938-946, 2017 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-27665453

RESUMO

Biological invasions are an important problem of human-induced changes at a global scale. Invasive plants can modify soil nutrient pools and element cycling, creating feedbacks that potentially stabilize current or accelerate further invasion, and prevent re-establishment of native species. The aim of this study was to compare the effects of Reynoutria japonica, Rudbeckia laciniata and Solidago gigantea, invading non-forest areas located within or outside river valleys, on soil physical and chemical parameters, including soil moisture, element concentrations, organic matter content and pH. Additionally, invasion effects on plant species number and total plant cover were assessed. The concentrations of elements in shoots and roots of invasive and native plants were also measured. Split-plot ANOVA revealed that the invasions significantly reduced plant species number, but did not affect most soil physical and chemical properties. The invasions decreased total P concentration and increased N-NO3 concentration in soil in comparison to native vegetation, though the latter only in the case of R. japonica. The influence of invasion on soil properties did not depend on location (within- or outside valleys). The lack of invasion effects on most soil properties does not necessarily imply the lack of influence of invasive plants, but may suggest that the direction of the changes varies among replicate sites and there are no general patterns of invasion-induced alterations for these parameters. Tissue element concentrations, with the exception of Mg, did not differ between invasive and native plants, and were not related to soil element concentrations.


Assuntos
Espécies Introduzidas , Polygonaceae/crescimento & desenvolvimento , Rudbeckia/crescimento & desenvolvimento , Solo/química , Solidago/crescimento & desenvolvimento , Raízes de Plantas , Polônia , Microbiologia do Solo
6.
Phytopathology ; 106(7): 752-61, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27003506

RESUMO

The oomycete Plasmopara halstedii emerged at the onset of the 21st century as a destructive new pathogen causing downy mildew disease of ornamental Rudbeckia fulgida (rudbeckia) in the United States. The pathogen is also a significant global problem of sunflower (Helianthus annuus) and is widely regarded as the cause of downy mildew affecting 35 Asteraceae genera. To determine whether rudbeckia and sunflower downy mildew are caused by the same genotypes, population genetic and phylogenetic analyses were performed. A draft genome assembly of a P. halstedii isolate from sunflower was generated and used to design 15 polymorphic simple sequence repeat (SSR) markers. SSRs and two sequenced phylogenetic markers measured differentiation between 232 P. halstedii samples collected from 1883 to 2014. Samples clustered into two main groups, corresponding to host origin. Sunflower-derived samples separated into eight admixed subclusters, and rudbeckia-derived samples further separated into three subclusters. Pre-epidemic rudbeckia samples clustered separately from modern strains. Despite the observed genetic distinction based on host origin, P. halstedii from rudbeckia could infect sunflower, and exhibited the virulence phenotype of race 734. These data indicate that the newly emergent pathogen populations infecting commercial rudbeckia are a different species from sunflower-infecting strains, notwithstanding cross-infectivity, and genetically distinct from pre-epidemic populations infecting native rudbeckia hosts.


Assuntos
Helianthus/microbiologia , Oomicetos/genética , Rudbeckia/microbiologia , Genótipo , Técnicas de Genotipagem , Especificidade de Hospedeiro , Interações Hospedeiro-Patógeno , Filogenia , Doenças das Plantas/microbiologia
7.
Nat Prod Res ; 28(12): 909-13, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24678714

RESUMO

A phytochemical investigation on the 5-lipoxygenase (5-LOX) inhibitory methanolic extract of Rudbeckia hirta L. flowers yielded 10 phenolic metabolites, including three phenolic acids, two phenolic acid esters, four flavonol glycosides and a trimethylated flavonol. The structures of the isolated metabolites were determined on the basis of spectroscopic analyses and by comparison with the literature data. Seven of these metabolites were isolated for the first time from the genus Rudbeckia. The in vitro 5-LOX inhibitory, immunomodulatory and antioxidant (oxygen radical absorbance capacity) activities of the isolated compounds were evaluated, and the results provided a new scientific evidence for the ethnopharmacological use of the herb in inflammatory conditions.


Assuntos
Anti-Inflamatórios/isolamento & purificação , Anti-Inflamatórios/farmacologia , Antioxidantes/isolamento & purificação , Antioxidantes/farmacologia , Araquidonato 5-Lipoxigenase/efeitos dos fármacos , Flavonóis/isolamento & purificação , Flavonóis/farmacologia , Flores/química , Glicosídeos/isolamento & purificação , Glicosídeos/farmacologia , Fatores Imunológicos/isolamento & purificação , Fatores Imunológicos/farmacologia , Inibidores de Lipoxigenase/isolamento & purificação , Inibidores de Lipoxigenase/farmacologia , Fenóis/isolamento & purificação , Fenóis/farmacologia , Plantas Medicinais/química , Rudbeckia/química , Anti-Inflamatórios/química , Antioxidantes/química , Flavonóis/química , Glicosídeos/química , Fatores Imunológicos/química , Inibidores de Lipoxigenase/química , Fenóis/química , Extratos Vegetais/química
8.
Arch Pharm Res ; 37(7): 834-8, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24062080

RESUMO

The phytochemical investigation of Rudbeckia laciniata L. obtained a new flavonol glycoside (1), together with four flavonol glycosides (2-5) and eight quinic acid derivatives (6-13). The structure was elucidation by means of spectroscopic methods and chemical evidence. The isolated compounds were tested for cytotoxicity against four human tumor cell lines in vitro using the sulforhodamine B bioassay.


Assuntos
Medicamentos de Ervas Chinesas/isolamento & purificação , Flavonóis/isolamento & purificação , Glicosídeos/isolamento & purificação , Componentes Aéreos da Planta , Rudbeckia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Medicamentos de Ervas Chinesas/química , Medicamentos de Ervas Chinesas/toxicidade , Flavonóis/química , Flavonóis/toxicidade , Glicosídeos/química , Glicosídeos/toxicidade , Humanos
9.
Nat Prod Res ; 27(24): 2281-5, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23962140

RESUMO

A new highly oxygenated pseudoguaianolide, rudbeckolide (1), was isolated from Rudbeckia hirta L. flowers. The structure of this terpenoid lactone was established on the basis of extensive 1D and 2D NMR spectroscopic analyses. The compound exhibited strong 5-lipoxygenase inhibitory activity (84.9% inhibition at 10 µg/mL) in vitro and the result provided partial evidence for the usage of the plant as traditional medicine.


Assuntos
Araquidonato 5-Lipoxigenase/metabolismo , Flores/química , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Rudbeckia/química , Ativação Enzimática/efeitos dos fármacos , Estrutura Molecular
10.
Environ Pollut ; 160(1): 74-81, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22035928

RESUMO

Ozone-sensitive and -tolerant individuals of cutleaf coneflower (Rudbeckia laciniata L.) were compared for their gas exchange characteristics and total non-structural carbohydrates at Purchase Knob, a high elevation site in Great Smoky Mountains National Park, USA. Photosynthesis and stomatal conductance decreased with increased foliar stipple. Sensitive plants had lower photosynthetic rates for all leaves, except the very youngest and oldest when compared to tolerant plants. Stomatal conductance decreased with increasing leaf age, but no ozone-sensitivity differences were found. Lower leaves had less starch than upper ones, while leaves on sensitive plants had less than those on tolerant plants. These results show that ambient levels of ozone in Great Smoky Mountains National Park can adversely affect gas exchange, water use efficiency and leaf starch content in sensitive coneflower plants. Persistence of sensitive genotypes in the Park may be due to physiological recovery in low ozone years.


Assuntos
Poluentes Atmosféricos/farmacologia , Ozônio/farmacologia , Rudbeckia/efeitos dos fármacos , Amido/metabolismo , Monitoramento Ambiental , Gases/metabolismo , Fotossíntese/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Rudbeckia/crescimento & desenvolvimento , Rudbeckia/metabolismo , Estados Unidos
11.
Phytochemistry ; 70(7): 889-98, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19477473

RESUMO

The UV-honey guides of Rudbeckia hirta were investigated by UV-photography, reflectance spectroscopy, LC-MS analysis and studies of the enzymes involved in the formation of the UV-absorbing flavonols present in the petals. It was shown for the first time that the typical bull's eye pattern is already established at the early stages of flower anthesis on the front side of the petal surface, but is hidden to pollinators until the buds are open and the petals are unfolded. The rear side of the petals remains UV-reflecting during the whole flower anthesis. Studies on the local distribution of 19 flavonols across the petals confirmed that the majority are concentrated in the basal part of the ray flower. However, in contrast to the earlier studies, eupatolitin 3-O-glucoside (6,7-dimethoxyquercetin 3-O-glucoside) was present in both the basal and apical parts of the petals, whereas eupatolin (6,7-dimethoxyquercetin 3-O-rhamnoside) was exclusively found in the apical parts. The enzymes involved in the formation of the flavonols in R. hirta were demonstrated for the first time. These include a rare flavonol 6-hydroxylase, which was identified as cytochrome P450-dependent monooxygenase and did not accept any methylated flavonol as substrate. All enzymes were present in the basal and apical parts of the petals, although some of them clearly showed higher activities in the basal part. This indicates that the local accumulation of flavonols in R. hirta is not achieved by a locally restricted presence of the enzymes involved in flavonol formation.


Assuntos
Flavonóis/análise , Flavonóis/metabolismo , Flores , Rudbeckia/química , Anatomia , Sistema Enzimático do Citocromo P-450/metabolismo , Flavonóis/química , Flores/anatomia & histologia , Flores/química , Flores/metabolismo , Glucosídeos/química , Glucosídeos/metabolismo , Mel , Oxigenases de Função Mista/metabolismo , Estrutura Molecular , Rudbeckia/enzimologia , Rudbeckia/metabolismo , Espectrofotometria Ultravioleta , Especificidade por Substrato
12.
Environ Pollut ; 157(3): 840-6, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19084304

RESUMO

Cutleaf coneflower (Rudbeckia laciniata L.) seedlings were placed into open-top chambers in May, 2004 and fumigated for 12 wks. Nine chambers were fumigated with either carbon-filtered air (CF), non-filtered air (NF) or twice-ambient (2x) ozone (O(3)). Ethylenediurea (EDU) was applied as a foliar spray weekly at 0 (control), 200, 400 or 600 ppm. Foliar injury occurred at ambient (30%) and elevated O(3) (100%). Elevated O(3) resulted in significant decreases in biomass and nutritive quality. Ethylenediurea reduced percent of leaves injured, but decreased root and total biomass. Foliar concentrations of cell-wall constituents were not affected by EDU alone; however, EDUxO(3) interactions were observed for total cell-wall constituents and lignocellulose fraction. Our results demonstrated that O(3) altered the physiology and productivity of cutleaf coneflower, and although reducing visible injury EDU may be phytotoxic at higher concentrations.


Assuntos
Poluentes Atmosféricos/toxicidade , Ozônio/toxicidade , Compostos de Fenilureia/farmacologia , Rudbeckia/efeitos dos fármacos , Biomassa , Ecotoxicologia/métodos , Compostos de Fenilureia/toxicidade , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/crescimento & desenvolvimento , Rudbeckia/crescimento & desenvolvimento , Plântula
13.
Oecologia ; 157(2): 279-86, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-18563451

RESUMO

It is not clear how plant species preferred as forage by rodents persist in prairie vegetation. To test permanence of suppression of wet-mesic prairie vegetation by vole (Microtus pennsylvanicus) herbivory in synthetic experimental communities, access treatments were reversed after 9 years of vole exclusion or access. Between 1996 and 2004, rye grass Elymus virginicus (Poaceae) and tick-trefoil Desmodium canadense (Fabaceae) achieved mean cover of up to 30 and 25%, respectively, in plots where voles were excluded, but disappeared from plots where voles had access. To determine whether these species remained vulnerable to vole herbivory as established adults, and to determine whether the species could recover if vole herbivory were removed, access treatments were reversed at the end of the 2004 growing season and monitored through 2007. Repeated measures ANOVA demonstrated dramatic vole suppression of established E. virginicus, but not D. canadense, indicating continuing vulnerability of the grass but not of the adult legume. Release from vole herbivory resulted in re-growth of rye, but not tick-trefoil, which was apparently suppressed by established vegetation. Two additional common planted species did not respond to treatment reversal, nor did 11 much less common planted species that comprised a minor portion of the vegetation. Dominant perennial black-eyed Susan Rudbeckia subtomentosa (Asteraceae) did not change in plant numbers by year or treatment, but expanded or contracted in stems per plant and cover as E. virginicus was suppressed or released by vole herbivory or its absence. Results indicate that preferred food plants may persist through capacity to quickly recover during periods of relative vole scarcity, or reach a refuge in maturity.


Assuntos
Arvicolinae/fisiologia , Elymus/crescimento & desenvolvimento , Fabaceae/crescimento & desenvolvimento , Comportamento Alimentar , Animais , Densidade Demográfica , Dinâmica Populacional , Rudbeckia/crescimento & desenvolvimento
14.
New Phytol ; 173(1): 100-9, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17176397

RESUMO

* Morphological and physiological attributes were assessed to elucidate the underlying mechanisms of ozone (O(3)) sensitivity in a highly sensitive species, cutleaf coneflower (Rudbeckia laciniata var. digitata). * Foliage at the same height in the canopy on paired O(3)-sensitive and -insensitive cutleaf coneflowers was assessed for level of foliar symptoms, stomatal density, stomatal responsiveness to dynamic changes in light and leaf-to-air vapor pressure deficit (VPD), steady-state responses to light and CO(2), intrinsic transpirational efficiency, and plant water balance. * There were no morphological differences between the sensitivity types that might have contributed to greater O(3) uptake in sensitive individuals. Stomata of sensitive plants were less responsive than those of insensitive plants to experimentally increased and decreased light intensities, and to increased VPD. O(3)-insensitive plants had greater intrinsic transpirational efficiencies, greater maximum assimilation rates under saturating CO(2) and light, and greater carboxylation rates. * Different physiological attributes vary independently within an individual plant, which collectively confer sensitivity or insensitivity to O(3) injury.


Assuntos
Ozônio/metabolismo , Rudbeckia/fisiologia , Dióxido de Carbono/metabolismo , Luz , North Carolina , Folhas de Planta/anatomia & histologia , Folhas de Planta/fisiologia , Folhas de Planta/efeitos da radiação , Transpiração Vegetal , Pressão , Rudbeckia/anatomia & histologia , Rudbeckia/efeitos da radiação , Água/metabolismo
15.
Photosynth Res ; 87(3): 281-6, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16699918

RESUMO

The ability of the SPAD-502 chlorophyll meter to quantify chlorophyll amounts in ozone-affected leaves of cutleaf coneflower (Rudbeckia laciniata var. digitata) was assessed in this study. When relatively uninjured leaves were measured (percent leaf area affected by stipple less than 6%), SPAD meter readings were linearly related to total chlorophyll with an adjusted R (2) of 0.84. However, when leaves with foliar injury (characterized as a purple to brownish stipple on the upper leaf surface affecting more than 6% of the leaf area) were added, likelihood ratio tests showed that it was no longer possible to use the same equation to obtain chlorophyll estimations for both classes of leaves. Either an equation with a common slope or a common intercept was necessary. We suspect several factors are involved in altering the calibration of the SPAD meter for measuring chlorophyll amounts in visibly ozone-injured leaves, with the most likely being changes in either light absorption or scattering resulting from tissue necrosis.


Assuntos
Clorofila/metabolismo , Ozônio/farmacologia , Doenças das Plantas , Folhas de Planta/efeitos dos fármacos , Rudbeckia/efeitos dos fármacos
16.
Ecology ; 87(3): 665-74, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16602296

RESUMO

Relatively little is known about how the life histories of perennial forb species, and especially their lifetime patterns of growth, vary across environmental gradients. We used a post hoc approach (herb-chronology) to determine plant age and previous growth (width of successive annual rings in roots) in three species of perennial forb (two long-lived species [Penstemon venustus, Lupinus laxiflorus] and one short-lived [Rudbeckia occidentalis]) along a 1000-m altitudinal gradient in the Wallowa Mountains (northeast Oregon, USA). Plants from the highest altitude tended to be considerably older and produced up to five times as many flowering shoots as lowland plants. In addition, mean ring widths of high-altitude plants were about half those of lowland plants. In plants from low and intermediate altitudes, ring width either decreased linearly or varied inconsistently during the life of the plant. In contrast, ring widths of high-altitude plants increased at first and later decreased, resulting in curvilinear growth trajectories that were highly consistent among species. Together, these data for three ecologically distinct forb species provide evidence of a consistent shift toward more conservative and strongly constrained life histories at higher altitudes. More generally, the results indicate the possible importance of changes in selection pressures across strong environmental gradients on life history strategies within a single species.


Assuntos
Altitude , Lupinus/crescimento & desenvolvimento , Penstemon/crescimento & desenvolvimento , Rudbeckia/crescimento & desenvolvimento , Lupinus/anatomia & histologia , Penstemon/anatomia & histologia , Fenômenos Fisiológicos Vegetais , Rudbeckia/anatomia & histologia , Especificidade da Espécie , Fatores de Tempo
17.
Environ Pollut ; 143(3): 427-34, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16460853

RESUMO

Cutleaf coneflower (Rudbeckia laciniata L.), crown-beard (Verbesina occidentalis Walt.), and tall milkweed (Asclepias exaltata L.) are wildflower species native to Great Smoky Mountains National Park (U.S.A.). Natural populations of each species were analyzed for leaf ascorbic acid (AA) and dehydroascorbic acid (DHA) to assess the role of ascorbate in protecting the plants from ozone stress. Tall milkweed contained greater quantities of AA (7-10 micromol g(-1) fresh weight) than crown-beard (2-4 micromol g(-1) fresh weight) or cutleaf coneflower (0.5-2 micromol g(-1) fresh weight). DHA was elevated in crown-beard and cutleaf coneflower relative to tall milkweed suggesting a diminished capacity for converting DHA into AA. Tall milkweed accumulated AA in the leaf apoplast (30-100 nmol g(-1) fresh weight) with individuals expressing ozone foliar injury symptoms late in the season having less apoplast AA. In contrast, AA was not present in the leaf apoplast of either crown-beard or cutleaf coneflower. Unidentified antioxidant compounds were present in the leaf apoplast of all three species. Overall, distinct differences in antioxidant metabolism were found in the wildflower species that corresponded with differences in ozone sensitivity.


Assuntos
Poluentes Atmosféricos/toxicidade , Asclepias/metabolismo , Ácido Ascórbico/metabolismo , Asteraceae/metabolismo , Ozônio/toxicidade , Inglaterra , Monitoramento Ambiental , Humanos , Folhas de Planta/metabolismo , Rudbeckia/metabolismo , Estações do Ano , Verbesina/metabolismo
18.
Environ Pollut ; 131(2): 295-303, 2004 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-15234096

RESUMO

Although there has been a great deal of research on ozone, interest in exposure of native, herbaceous species is relatively recent and it is still not clear what role the pollutant has in their ecological fitness. The ozone exposure of a plant is usually expressed in terms of the concentration above the canopy or as a time-weighted index. However, to understand the physiological effects of ozone it is necessary to quantify the ozone flux to individual leaves as they develop, which requires knowing the deposition velocity and concentration of the pollutant as a function of height throughout the plant canopy. We used a high-order closure model of sub-canopy turbulence to estimate ozone profiles in stands of cutleaf coneflower (Rudbeckia laciniata L.) located in the Great Smoky Mountains National Park, USA. The model was run for periods coinciding with a short field study, during which we measured vertical concentration profiles of ozone along with measurements of atmospheric turbulence and other meteorological and plant variables. Predictions of ozone profiles by the model are compared with observations throughout the canopy.


Assuntos
Poluentes Atmosféricos/farmacocinética , Ozônio/farmacocinética , Rudbeckia/metabolismo , Poluentes Atmosféricos/análise , Ecossistema , Monitoramento Ambiental/métodos , Conceitos Meteorológicos , Modelos Biológicos , Ozônio/análise , Folhas de Planta/metabolismo , Folhas de Planta/fisiologia
19.
Environ Pollut ; 125(1): 53-9, 2003.
Artigo em Inglês | MEDLINE | ID: mdl-12804827

RESUMO

Incidence and severity of visible foliar ozone injury on cutleaf coneflower (Rudbeckia laciniata L.) and crown-beard (Verbesina occidentalis Walt.) were determined along selected trails at three locations in Great Smoky Mountains National Park during the summers of 2000 and 2001: Clingmans Dome, Cherokee Orchard Road and Purchase Knob. Cutleaf coneflower exhibited a greater amount of foliar injury than crown-beard each year of the 2-year study. Incidence and severity of injury was significantly greater for cutleaf coneflower growing near the edge of the Clingmans Dome trail than in the interior of the stand. Injury was greater at Clingmans Dome than Purchase Knob (70% vs. 40% ozone-injured plants, respectively), coincident with greater ozone exposures. In contrast to Clingmans Dome, there were no differences in injury between plants growing near- and off-trail at Purchase Knob. Differences in sensitivity to ozone were not observed for crown-beard growing near the edge compared with the interior of the stand adjacent to the Cherokee Orchard Road Loop. Ozone injury was greatest on the lower leaves for both species sampled with over 95% of the injured leaves occurring on the lower 50% of the plant. This is the first report of foliar ozone injury on these plant species in situ, in the Park, illustrating the great variability in symptom expression with time, and within and between populations.


Assuntos
Poluentes Atmosféricos/efeitos adversos , Ozônio/efeitos adversos , Rudbeckia/efeitos dos fármacos , Verbesina/efeitos dos fármacos , Monitoramento Ambiental/métodos , Folhas de Planta/efeitos dos fármacos , Tennessee
20.
Environ Pollut ; 125(1): 61-70, 2003.
Artigo em Inglês | MEDLINE | ID: mdl-12804828

RESUMO

Visible injury caused by ozone is recorded every year in native plant species growing in Great Smoky Mountains National Park (USA). One of the most sensitive species, cutleaf coneflower (Rudbeckia laciniata L.), shows great variation in symptoms between and within populations but the causes of this variation and its ecological significance are currently unknown. This paper presents data relating to genetic variation, ozone concentrations, stomatal conductance and light (PAR) within populations. The data show that populations differ in genetic diversity, one consisting of only three genets while another was very diverse. In the former population, symptoms varied greatly within a single genet, pointing to a large micro-environmental influence. Measurements of ozone, stomatal conductance and PAR within plant canopies suggest that variation in symptom expression is unlikely to be due to differences in ozone flux and more likely to be due to variation in light. The variation in visible symptoms raises the question of what bioindicators actually indicate, and it suggests that symptoms should be interpreted with great caution until the underlying causes of that variation are fully understood.


Assuntos
Poluentes Atmosféricos/efeitos adversos , Monitoramento Ambiental/métodos , Ozônio/efeitos adversos , Rudbeckia/efeitos dos fármacos , Variação Genética , Estimulação Luminosa , Folhas de Planta/efeitos dos fármacos , Rudbeckia/genética , Tennessee
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