| thigmomorphogenesis: the role of ethylene in the response of pinus taeda and abies fraseri to mechanical perturbation. | ethylene production was monitored for 48 h in two half-sibs of pinus taeda l. grown in the greenhouse and given mechanical perturbation (mp) by flexing; and for 22 h in abies fraseri (pursh) poir. grown in the field and exposed to wind-mediated mp. both species produced a peak of ethylene 18 h after mp. seedlings of p. taeda exposed to mp for the duration of the growing season (preconditioned) produced less ethylene compared to non-mp controls, with a peak production at 8 h. one half-sib whic ... | 1986 | 11538656 |
| post-transcriptional gene silencing induced by short interfering rnas in cultured transgenic plant cells. | short interfering rna (sirna) is widely used for studying post-transcriptional gene silencing and holds great promise as a tool for both identifying function of novel genes and validating drug targets. two sirna fragments (sirna-a and -b), which were designed against different specific areas of coding region of the same target green fluorescent protein (gfp) gene, were used to silence gfp expression in cultured gfp transgenic cells of rice (oryza sativa l.; os), cotton (gossypium hirsutum l.; gh ... | 2004 | 15629049 |
| low clouds and cloud immersion enhance photosynthesis in understory species of a southern appalachian spruce-fir forest (usa). | high-altitude forests of the southern appalachian mountains (usa) are frequently immersed in clouds, as are many mountain forests. they may be particularly sensitive to predicted increases in cloud base altitude with global warming. however, few studies have addressed the impacts of immersion on incident sunlight and photosynthesis. understory sunlight (photosynthetically active radiation, par) was measured during clear, low cloud, and cloud-immersed conditions at mount mitchell and roan mountai ... | 2006 | 21642107 |
| dexamethasone-inducible green fluorescent protein gene expression in transgenic plant cells. | genomic research has made a large number of sequences of novel genes or expressed sequence tags available. to investigate functions of these genes, a system for conditional control of gene expression would be a useful tool. inducible transgene expression that uses green fluorescent protein gene (gfp) as a reporter gene has been investigated in transgenic cell lines of cotton (cot; gossypium hirsutum l.), fraser fir [fra; abies fraseri (pursh) poir], nordmann fir (nor; abies nordmanniana lk.), an ... | 2004 | 15629039 |
| evaluation of chemical controls and entomopathogenic nematodes for control of phyllophaga white grubs in a fraser fir production field. | the results of 2 yr of field trials evaluating various chemical and biological controls of phyllophaga anxia (leconte) white grubs in a fraser fir [abies fraseri (pursh) poir] christmas tree production field are reported here. chemical insecticides evaluated included bifenthrin, chlorantraniliprole, thiamethoxam, and time-released imidacloprid tablets (coretect, bayer cropscience, research triangle park, nc). entomopathogenic nematodes evaluated included heterorhabditis bacteriophora (poinar) an ... | 2010 | 21309216 |
| genetic discontinuity revealed by chloroplast microsatellites in eastern north american abies (pinaceae). | development of conservation strategies for fraser fir (abies fraseri) in the southern appalachian mountains depends in part on recognition of the extent to which fraser fir is genetically distinct from the closely related balsam (a. balsamea) and intermediate (a. balsamea var. phanerolepis) fir. these sibling species have exhibited intergrading, clinal variation in morphological, chemical, and genetic characteristics in prior research. chloroplast microsatellite markers were polymerase chain rea ... | 2000 | 10860908 |
| clouds homogenize shoot temperatures, transpiration, and photosynthesis within crowns of abies fraseri (pursh.) poiret. | multiple studies have examined the effects of clouds on shoot and canopy-level microclimate and physiological processes; none have yet done so on the scale of individual plant crowns. we compared incident photosynthetically active radiation (par), leaf temperatures, chlorophyll fluorescence, and photosynthetic gas exchange of shoots in three different spatial locations of abies fraseri crowns on sunny (clear to partly cloudy) versus overcast days. the field site was a fraser fir farm (1038 m ele ... | 2017 | 28070700 |
| an extractive removal step optimized for a high-throughput α-cellulose extraction method for δ13c and δ18o stable isotope ratio analysis in conifer tree rings. | stable isotope ratios (δ(13)c and δ(18)o) of tree-ring α-cellulose are important tools in paleoclimatology, ecology, plant physiology and genetics. the multiple sample isolation system for solids (msiss) was a major advance in the tree-ring α-cellulose extraction methods, offering greater throughput and reduced labor input compared to traditional alternatives. however, the usability of the method for resinous conifer species may be limited by the need to remove extractives from some conifer spec ... | 2016 | 27672185 |
| foliar uptake, carbon fluxes and water status are affected by the timing of daily fog in saplings from a threatened cloud forest. | in cloud forests, foliar uptake (fu) of water has been reported for numerous species, possibly acting to relieve daily water and carbon stress. while the prevalence of fu seems common, how daily variation in fog timing may affect this process has not been studied. we examined the quantity of fu, water potentials, gas exchange and abiotic variation at the beginning and end of a 9-day exposure to fog in a glasshouse setting. saplings of abies fraseri (pursh) poir. and picea rubens sarg. were expos ... | 2014 | 24835239 |
| cloud immersion: an important water source for spruce and fir saplings in the southern appalachian mountains. | cloud immersion can provide a potentially important moisture subsidy to plants in areas of frequent fog including the threatened spruce-fir communities of the southern appalachian mountains (usa). these mountaintop communities grow only above ~1,500 m elevation, harbor the endemic abies fraseri, and have been proposed to exist because of frequent cloud immersion. while several studies have demonstrated the importance of cloud immersion to plant water balance, no study has evaluated the proportio ... | 2014 | 24271421 |
| ecophysiological importance of cloud immersion in a relic spruce-fir forest at elevational limits, southern appalachian mountains, usa. | climate warming predicts changes to the frequency and height of cloud-immersion events in mountain communities. threatened southern appalachian spruce-fir forests have been suggested to persist because of frequent periods of cloud immersion. these relic forests exist on only seven mountaintop areas, grow only above ca. 1,500 m elevation (maximum 2,037 m), and harbor the endemic abies fraseri. to predict future distribution, we examined the ecophysiological effects of cloud immersion on saplings ... | 2013 | 23576108 |
| two novel techniques to screen abies seedlings for resistance to the balsam woolly adelgid, adelges piceae. | since its introduction into the southern appalachians in the 1950s, the balsam woolly adelgid, adelges piceae ratzeburg (hemiptera: adelgidae), has devastated native populations of fraser fir, abies fraseri (pursh) poir. (pinales: pinaceae), and has become a major pest in christmas tree plantations requiring expensive chemical treatments. adelges piceae-resistant fraser fir trees would lessen costs for the christmas tree industry and assist in the restoration of native stands. resistance screeni ... | 2011 | 22239164 |
| polymerase chain reaction preparation of template for massively parallel pyrosequencing. | massively parallel pyrosequencing of dna fragments immobilized on beads has been applied to genome survey sequencing and transcriptome analysis of a variety of eukaryotic organisms, including laboratory model species, agricultural crops and livestock, and species of interest to population biologists and ecologists. preparation of sufficient high-quality template for sequencing has been an obstacle to sequence analysis of nucleic acids from tissues or cell types available in limited quantities. w ... | 2009 | 19503624 |
| impacts of cloud immersion on microclimate, photosynthesis and water relations of abies fraseri (pursh.) poiret in a temperate mountain cloud forest. | the red spruce-fraser fir ecosystem [picea rubens sarg.-abies fraseri (pursh) poir.] of the southern appalachian mountains, usa, is a temperate zone cloud forest immersed in clouds for 30-40% of a typical summer day, and experiencing immersion on about 65% of all days annually. we compared the microclimate, photosynthetic gas exchange, and water relations of fraser fir trees in open areas during cloud-immersed, low-cloud, or sunny periods. in contrast to sunny periods, cloud immersion reduced in ... | 2008 | 18825418 |
| cloud immersion alters microclimate, photosynthesis and water relations in rhododendron catawbiense and abies fraseri seedlings in the southern appalachian mountains, usa. | the high altitude spruce-fir (abies fraseri (pursh) poiret.-picea rubens sarg.) forests of the southern appalachian mountains, usa, experience frequent cloud immersion. recent studies indicate that cloud bases may have risen over the past 30 years, resulting in less frequent forest cloud immersion, and that further increases in cloud base height are likely in the event of continued climate warming. to assess the impact of this trend on the regeneration of high altitude spruce-fir forests and the ... | 2008 | 18171662 |
| leaf gas exchange of understory spruce-fir saplings in relict cloud forests, southern appalachian mountains, usa. | the southern appalachian spruce-fir (picea rubens sarg. and abies fraseri (pursh) poir.) forest is found only on high altitude mountain tops that receive copious precipitation ( > 2000 mm year(-1)) and experience frequent cloud immersion. these high-elevation, temperate rain forests are immersed in clouds on approximately 65% of the total growth season days and for 30-40% of a typical summer day, and cloud deposition accounts for up to 50% of their annual water budget. we investigated environmen ... | 2008 | 17938120 |
| leaf architecture and direction of incident light influence mesophyll fluorescence profiles. | light propagation and distribution inside leaves have been recognized as important processes influencing photosynthesis. monochromatic light absorption across the mesophyll was measured using chlorophyll fluorescence generated from illumination of the cut edge (epi-illumination), as well as the adaxial or abaxial surfaces of the leaf. species were selected that had basic leaf types: laminar leaf with adaxial palisade layer (rhododendron catawbiense), needle with palisade (abies fraseri), and nee ... | 2005 | 21646160 |
| refugial forests of the southern appalachians: photosynthesis and survival in current-year abies fraseri seedlings. | fraser fir (abies fraseri (pursh) poiret) is an endemic, high-elevation conifer confined to six relict mountaintop communities in the southern appalachian mountains, usa. high adult mortality has occurred over the past 50 years, possibly the result of an introduced insect (adelges piceae ratzeburg), air pollution, or both. knowledge of the mechanisms of and limitations to seedling establishment may allow reestablisment and perpetuation of this unique community type, notwithstanding global climat ... | 2005 | 16105805 |
| is there synchronicity in nitrogen input and output fluxes at the noland divide watershed, a small n-saturated forested catchment in the great smoky mountains national park? | high-elevation red spruce [picea rubens sarg.]-fraser fir [abies fraseri (pursh.) poir] forests in the southern appalachians currently receive large nitrogen (n) inputs via atmospheric deposition (30 kg n ha(-1) year(-1)) but have limited n retention capacity due to a combination of stand age, heavy fir mortality caused by exotic insect infestations, and numerous gaps caused by windfalls and ice storms. this study examined the magnitude and timing of the n fluxes into, through, and out of a smal ... | 2001 | 12805804 |
| amended description of pratylenchus macrostylus wu, 1971 with sem observations. | the description of pratylenchus macrostylus wu is amended using specimens collected from fraser fir and red spruce in the black mountains of north carolina. measurements of females in north carolina overlap those of the type series. however, stylet length (21.8-27.8 mum, 24.7 ñ 1.1) is greater in north carolina specimens, which also have a longer body length and greater c ratio. heads of the north carolina specimens are divided into lateral and submedian segments which taper and fuse with oral d ... | 1991 | 19283100 |
| structure and function of flexure wood in abies fraseri. | wood produced during flexure in one-year-old leaders of abies fraseri (pursh) poir. (fraser fir) was analyzed anatomically and radio-densitometrically. more xylem cells were produced in stems subjected to flexing than in stems that were not flexed. the lumens of tracheids produced in response to flexure were smaller than the lumens of tracheids in normal wood. this was manifest as an increase in the cell wall area/cell lumen area ratio. microfibril orientation in flexure-induced wood approached ... | 1989 | 14973003 |
| interactions of insects, trees and air pollutants. | hypotheses of forest decline are summarized. stressed trees may be a more suitable food source for invertebrate herbivores than unstressed trees because stress causes an increase in the tissue content of soluble nitrogenous compounds. there is reasonable correlative evidence that air pollutants influence the outbreak patterns of forest insect species. in some cases, formerly innocuous insects may become pests. the occurrence of specific insect pests with specific air contaminants is reviewed. em ... | 1987 | 14975836 |
| thigmomorphogenesis: field and laboratory studies of abies fraseri in response to wind or mechanical perturbation. | field- and greenhouse-grown abies fraseri (pursh) poir. (fraser fir) were analyzed for wind- or mechanically-induced flexure changes. these changes included inhibition of stem and needle elongation, reinforcement of branch bases around the stem, and increased radial growth in the direction of the mechanical perturbation (mp). mature trees exposed to high wind conditions were severely flag-formed. these modified tree crowns had a lower drag than crowns of non-flag formed trees in wind-tunnel test ... | 1986 | 11538654 |