| episodic recruitment of the seedling banks in balsam fir and white spruce. | | 2012 | 23204491 |
| changes in hormone flux and signaling in white spruce (picea glauca) seeds during the transition from dormancy to germination in response to temperature cues. | seeds use environmental cues such as temperature to coordinate the timing of their germination, allowing plants to synchronize their life history with the seasons. winter chilling is of central importance to alleviate seed dormancy, but very little is known of how chilling responses are regulated in conifer seeds. white spruce (picea glauca) is an important conifer species of boreal forests in the north american taiga. the recent sequencing and assembly of the white spruce genome allows for comp ... | 2015 | 26680643 |
| expression of panac01, a picea abies cup-shaped cotyledon orthologue, is regulated by polar auxin transport and associated with differentiation of the shoot apical meristem and formation of separated cotyledons. | during embryo development in most gymnosperms, the establishment of the shoot apical meristem (sam) occurs concomitantly with the formation of a crown of cotyledons surrounding the sam. it has previously been shown that the differentiation of cotyledons in somatic embryos of picea abies is dependent on polar auxin transport (pat). in the angiosperm model plant, arabidopsis thaliana, the establishment of cotyledonary boundaries and the embryonal sam is dependent on pat and the expression of the c ... | 2012 | 22778149 |
| the endo-1,4-β-glucanase korrigan exhibits functional conservation between gymnosperms and angiosperms and is required for proper cell wall formation in gymnosperms. | the evolution of compositional polymers and their complex arrangement and deposition in the cell walls of terrestrial plants included the acquisition of key protein functions. a membrane-bound endoglucanase, termed korrigan (kor), has been shown to be required for proper cellulose synthesis. to date, no extensive characterization of the gymnosperm kor has been undertaken. characterization of the white spruce (picea glauca) gene encoding kor (pgkor) shows conserved protein features such as polari ... | 2012 | 22150158 |
| a white spruce gene catalog for conifer genome analyses. | several angiosperm plant genomes, including arabidopsis (arabidopsis thaliana), rice (oryza sativa), poplar (populus trichocarpa), and grapevine (vitis vinifera), have been sequenced, but the lack of reference genomes in gymnosperm phyla reduces our understanding of plant evolution and restricts the potential impacts of genomics research. a gene catalog was developed for the conifer tree picea glauca (white spruce) through large-scale expressed sequence tag sequencing and full-length cdna sequen ... | 2011 | 21730200 |
| hormonally regulated overexpression of arabidopsis wus and conifer lec1 (chap3a) in transgenic white spruce: implications for somatic embryo development and somatic seedling growth. | adult conifers are still recalcitrant in clonal propagation despite significant advances in forest tree biotechnology. plant regeneration through somatic embryogenesis from explants older than mature zygotic embryos is either difficult or impossible to achieve. to investigate if ectopic expression of transcription factors involved in the induction of the embryogenic process would induce somatic embryogenesis in picea glauca (white spruce) somatic plants, we used the leafy-cotyledon1 homolog clon ... | 2010 | 20424847 |
| constancy of nitrogen turnover kinetics in the plant cell: insights into the integration of subcellular n fluxes. | compartmental analysis with 13n was used to determine cytosolic nitrate (no3-) pools, and their turnover rates, in roots of intact barley (hordeum vulgare l. cv klondike) seedlings. influx, efflux, flux to the vacuole and assimilation, and flux to the xylem, varied as much as 300-fold over a wide range of external no3- conditions. by contrast, the kinetic constant kc describing cytosolic no3- turnover varied by less than 4% from a mean value of 0.0407 min(-1). accordingly, cytosolic no3- pools v ... | 2001 | 11469581 |
| insect herbivory (choristoneura fumiferana, tortricidea) underlies tree population structure (picea glauca, pinaceae). | variation in insect herbivory can lead to population structure in plant hosts as indicated by defence traits. in annual herbaceous, defence traits may vary between geographic areas but evidence of such patterns is lacking for long-lived species. this may result from the variety of selection pressures from herbivores, long distance gene flow, genome properties, and lack of research. we investigated the antagonistic interaction between white spruce (picea glauca) and spruce budworm (sbw, choriston ... | 2017 | 28205578 |
| spruce budworm feeding and oviposition are stimulated by monoterpenes in white spruce epicuticular waxes. | monoterpenes, source of the distinctive odor of conifers, are generally considered plant defensive compounds. however, they are also known to act as long-range insect attractants, as they are volatile and permeate forest airspaces. moreover, they are lipid soluble and can be absorbed into plant epicuticular waxes. we test their role in short-range host plant choice by both adult females and larvae of a folivorous forest pest (choristoneura fumiferana). we conducted laboratory assays testing the ... | 2017 | 26463122 |
| expression of the β-glucosidase gene pgβglu-1 underpins natural resistance of white spruce against spruce budworm. | periodic outbreaks of spruce budworm (sbw) affect large areas of ecologically and economically important conifer forests in north america, causing tree mortality and reduced forest productivity. host resistance against sbw has been linked to growth phenology and the chemical composition of foliage, but the underlying molecular mechanisms and population variation are largely unknown. using a genomics approach, we discovered a β-glucosidase gene, pgβglu-1, whose expression levels and function unde ... | 2015 | 25302566 |
| tree phyllosphere bacterial communities: exploring the magnitude of intra- and inter-individual variation among host species. | the diversity and composition of the microbial community of tree leaves (the phyllosphere) varies among trees and host species and along spatial, temporal, and environmental gradients. phyllosphere community variation within the canopy of an individual tree exists but the importance of this variation relative to among-tree and among-species variation is poorly understood. sampling techniques employed for phyllosphere studies include picking leaves from one canopy location to mixing randomly sele ... | 2016 | 27635335 |
| host species identity, site and time drive temperate tree phyllosphere bacterial community structure. | the increasing awareness of the role of phyllosphere microbial communities in plant health calls for a greater understanding of their structure and dynamics in natural ecosystems. since most knowledge of tree phyllosphere bacterial communities has been gathered in tropical forests, our goal was to characterize the community structure and assembly dynamics of phyllosphere epiphytic bacterial communities in temperate forests in quebec, canada. we targeted five dominant tree species: acer saccharum ... | 2016 | 27316353 |
| allometric exponents as a tool to study the influence of climate on the trade-off between primary and secondary growth in major north-eastern american tree species. | trees invest in both primary (e.g. height) and secondary (e.g. diameter) growth. the trade-off between these investments varies between species and changes with the tree growing environment. to better establish this trade-off, readily available allometric exponents relating height to diameter at breast height (γ(h,dbh)) and stem volume to diameter at breast height (α(v,dbh)) were simultaneously studied. | 2016 | 26975315 |
| biogeographic variation in evergreen conifer needle longevity and impacts on boreal forest carbon cycle projections. | leaf life span is an important plant trait associated with interspecific variation in leaf, organismal, and ecosystem processes. we hypothesized that intraspecific variation in gymnosperm needle traits with latitude reflects both selection and acclimation for traits adaptive to the associated temperature and moisture gradient. this hypothesis was supported, because across 127 sites along a 2,160-km gradient in north america individuals of picea glauca, picea mariana, pinus banksiana, and abies b ... | 2014 | 25225397 |
| recovery kinetics of photochemical efficiency in winter stressed conifers: the effects of growth light environment, extent of the season and species. | evergreens undergo reductions in maximal photochemical efficiency (f(v)/f(m)) during winter due to increases in sustained thermal energy dissipation. upon removing winter stressed leaves to room temperature and low light, f(v)/f(m) recovers and can include both a rapid and a slow phase. the goal of this study was to determine whether the rapid component to recovery exists in winter stressed conifers at any point during the season in a seasonally extreme environment. additional goals were to comp ... | 2013 | 22575048 |
| carry-over effect of host nutritional quality on performance of spruce budworm progeny. | the effect of host nutritional quality on spruce budworm (choristoneura fumiferana (clemens)) parental and offspring performance was studied using field and laboratory rearing experiments, and foliar chemical analyses. foliage of balsam fir (abies balsamea (l.) mill.), white spruce (picea glauca (moench) voss) and black spruce (p. mariana (mill.) bsp) was used to rear the parental generation in the field, whereas an artificial diet was used to rear the progeny under laboratory conditions. import ... | 2012 | 22077965 |
| reproductive potential of balsam fir (abies balsamea), white spruce (picea glauca), and black spruce (p. mariana) at the ecotone between mixedwood and coniferous forests in the boreal zone of western quebec. | the reproductive potentials of balsam fir and white spruce (co-dominants in mixedwood forests) and black spruce (dominant in coniferous forests) were studied to explain the location of the ecotone between the two forest types in the boreal zone of quebec. four sites were selected along a latitudinal gradient crossing the ecotone. cone crop, number of seeds per cone, percentage filled seeds, and percentage germination were measured for each species. balsam fir and white spruce cone crops were sig ... | 2007 | 21636443 |
| absence of net long-term successional facilitation by alder in a boreal alaska floodplain. | long-term experiments provide a way to test presumed causes of successional or environmentally driven vegetation changes. early-successional nitrogen (n)-fixing plants are widely thought to facilitate productivity and vegetation development on n-poor sites, thus accounting for observed vegetation patterns later in succession. we tested this facilitative impact on vegetation development in a 23-yr field experiment on an interior alaska (usa) floodplain. on three replicate early-successional silt ... | 2016 | 27870053 |
| effects of kaolin-based particle film on spruce budworm (choristoneura fumiferana (lepidoptera: tortricidae)) oviposition in the laboratory. | a laboratory study conducted in 2003 determined the influence of a kaolin-based particle film (surround wp crop protectant) on spruce budworm (choristoneura fumiferana (clem)) oviposition. three concentrations (15, 30 and 60 g litre(-1) spray carrier) were applied to white spruce (picea glauca (moench) voss). when presented with different paired choices of oviposition surfaces, spruce budworms laid very few egg masses overall and showed no significant (p < 0.05) preference between kaolin-coated ... | 2005 | 16217725 |
| characterization of light-dependent regulation of state transitions in gymnosperms. | the goal of this study was to characterize the light-dependent regulation of state transitions in gymnosperms. two species of conifer were examined: eastern white pine (pinus strobus l.) and white spruce [picea glauca (moench) voss], as well as the angiosperm pumpkin (cucurbita pepo l. subsp. pepo). both diurnal time courses in the field and manipulated light experiments in growth chambers were conducted. results from chlorophyll fluorescence analysis indicated that pumpkin was able to use a lar ... | 2016 | 26802541 |
| tree-ring isotopes reveal drought sensitivity in trees killed by spruce beetle outbreaks in south-central alaska. | increasing temperatures have resulted in reduced growth and increased tree mortality across large areas of western north american forests. we use tree-ring isotope chronologies (δ(13) c and δ(18) o) from live and dead trees from four locations in south-central alaska, usa, to test whether white spruce trees killed by recent spruce beetle (dendroctonus rufipennis kirby) outbreaks showed evidence of drought stress prior to death. trees that were killed were more sensitive to spring/summer temperat ... | 2016 | 27755740 |
| contrasting patterns of diterpene acid induction by red pine and white spruce to simulated bark beetle attack, and interspecific differences in sensitivity among fungal associates. | conifers possess a suite of physiochemical defenses that protect their subcortical tissues from bark beetle - fungal complexes. these defenses include rapid induction of terpenoids and phenolics at the site of attack. studies of the distribution, induction, and bioactivity of conifer terpenoids have focused heavily on monoterpenes. we assessed induction of diterpene acids in white spruce (picea glauca) and red pine (pinus resinosa) to fungal associates of two bark beetles, and the responses of f ... | 2015 | 26003180 |
| an evaluation of british columbian beetle-killed hybrid spruce for bioethanol production. | the development of bioconversion technologies for production of fuels, chemicals, and power from renewable resources is currently a high priority for developed nations such as the united states, canada, and the european union as a way to improve national energy security and reduce greenhouse gas emissions. the widespread implementation of such technologies will require a sustainable supply of biomass from forestry and agriculture. forests are a major source of feedstocks for biofuels production ... | 2007 | 18478394 |
| seasonal effect on tree species classification in an urban environment using hyperspectral data, lidar, and an object- oriented approach. | the objective of the current study was to analyze the seasonal effect on differentiating tree species in an urban environment using multi-temporal hyperspectral data, light detection and ranging (lidar) data, and a tree species database collected from the field. two airborne imaging spectrometer for applications (aisa) hyperspectral images were collected, covering the summer and fall seasons. in order to make both datasets spatially and spectrally compatible, several preprocessing steps, includi ... | 2008 | 27879863 |