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  • 1
    Language: English
    In: The New phytologist, 2015-01-01, Vol.205 (1), p.102-115
    Description: The hydraulic properties of xylem and phloem differ but the magnitude and functional consequences of the differences are not well understood. Phloem and xylem functional areas, hydraulic conduit diameters and conduit frequency along the stems of trees were measured and expressed as allometric functions of stem diameter and distance from stem apex. Conductivities of phloem and xylem were estimated from these scaling relations. Compared with xylem, phloem conduits were smaller and occupied a slightly larger fraction of conducting tissue area. Ten times more xylem than phloem was annually produced along the stem. Scaling of the conduit diameters and cross-sectional areas with stem diameter were very similar in phloem and xylem. Phloem and xylem conduits scaled also similarly with distance from stem apex; widening downwards from the tree top, and reaching a plateau near the base of the living crown. Phloem conductivity was estimated to scale similarly to the conductivity of the outermost xylem ring, with the ratio of phloem to xylem conductivity being . 2%. However, xylem conductivity was estimated to increase more than phloem conductivity with increasing tree dimensions as a result of accumulation of xylem sapwood. Phloem partly compensated for its smaller conducting area and narrower conduits by having a slightly higher conduit frequency.
    Subject(s): Trees ; Full papers ; Sapwood ; Phloem ; Xylem ; Hydraulics ; Plant tissues ; Sieve elements ; Plants ; Diameters ; Stems ; conduit frequency ; allometry ; conifers ; conductivity ; conduit tapering ; phloem sieve cells ; xylem tracheids ; Picea abies ; Phloem - anatomy & histology ; Xylem - physiology ; Picea - anatomy & histology ; Xylem - anatomy & histology ; Picea - physiology ; Water - metabolism ; Phloem - physiology ; Plant Stems - physiology ; Analysis ; Hydrogeology
    ISSN: 0028-646X
    E-ISSN: 1469-8137
    Source: JSTOR Life Sciences
    Source: Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals
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  • 2
    Language: English
    In: Planta, 2015-09-01, Vol.242 (3), p.613-629
    Description: Main conclusion Phloem production and structural development were interlinked with seasonal variation in the primary and secondary metabolites of phloem. Novel microtechniques provided new perspectives on understanding phloem structure and chemistry. To gain new insights into phloem formation in Norway spruce (Picea abies), we monitored phloem cell production and seasonal variation in the primary and secondary metabolites of inner bark (non-structural carbohydrates and phenolic stilbene glucosides) during the 2012 growing season in southern and northern Finland. The structure of developing phloem was visualised in 3D by synchrotron X-ray microtomography. The chemical features of developing phloem tissues isolated by laser microdissection were analysed by chemical microanalysis. Within-year phloem formation was associated with seasonal changes in non-structural carbohydrates and phenolic extractive contents of inner bark. The onset of phloem cell production occurred in early and mid-May in southern and northern Finland, respectively. The maximal rate of phloem production and formation of a tangential band of axial phloem parenchyma occurred in mid-June, when total non-structural carbohydrates peaked (due to the high amount of starch). In contrast, soluble sugar content dropped during the most active growth period and increased in late summer and winter. The 3D visualisation showed that the new axial parenchyma clearly enlarged from June to August. Subcellular changes appeared to be associated with accumulation of stilbene glucosides and soluble sugars in the newest phloem. Stilbene glucosides also increased in inner bark during late summer and winter. Our findings may indicate that stilbene biosynthesis in older phloem predominantly occurs after the formation of the new band(s) of axial parenchyma. The complementary use of novel microtechniques provides new perspectives on the formation, structure, and chemistry of phloem.
    Subject(s): Life Sciences ; Carbohydrates ; Stilbene glucosides ; Laser microdissection ; Forestry ; Microtomography ; Phloem parenchyma ; Agriculture ; Ecology ; Plant Sciences ; Phenolics ; Picea - growth & development ; Phloem - metabolism ; Plant Bark - metabolism ; Plant Bark - growth & development ; Seasons ; Picea - metabolism ; Phloem - growth & development ; Physiological aspects ; Chemical properties ; Analysis ; Plant metabolites
    ISSN: 0032-0935
    E-ISSN: 1432-2048
    Source: JSTOR Ecology & Botany II
    Source: Alma/SFX Local Collection
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  • 3
    Language: English
    In: Polymers, 2020-01-22, Vol.12 (2), p.257
    Description: Injection molded biocomposite specimens were prepared by using four different weight percentages, i.e., 10%, 20%, 30%, and 40% of aspen ( L. and willow ( L.) wood particles in a biopolymeric matrix. Dog-bone test specimens were used for testing the physical, mechanical, and thermal properties, and microstructure of biocomposites. The tensile and bending strength changed with the change in weight percentages of wood particles and the bending stiffness increased with the increasing weight percentage of wood. In Brinell hardness, similar changes as a function of wood particle weight percentage were shown, and a relationship between hardness and tensile strength with wood content was also investigated. The prepared biocomposites could be an alternative for plastic-based materials and encourage the use of fast growing (aspen and willow) wood from short-rotation forests in biocomposites.
    Subject(s): willow ; tensile strength ; microstructure behavior ; biocomposite ; aspen ; injection molding ; bending strength ; short-rotation
    ISSN: 2073-4360
    E-ISSN: 2073-4360
    Source: Academic Search Ultimate
    Source: PubMed Central
    Source: Alma/SFX Local Collection
    Source: DOAJ Directory of Open Access Journals - Not for CDI Discovery
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  • 4
    Language: English
    In: Plant, cell and environment, 2017-10, Vol.40 (10), p.2160-2173
    Description: Preconditions of phloem transport in conifers are relatively unknown. We studied the variation of needle and inner bark axial osmotic gradients and xylem water potential in Scots pine and Norway spruce by measuring needle and inner bark osmolality in saplings and mature trees over several periods within a growing season. The needle and inner bark osmolality was strongly related to xylem water potential in all studied trees. Sugar concentrations were measured in Scots pine, and they had similar dynamics to inner bark osmolality. The sucrose quantity remained fairly constant over time and position, whereas the other sugars exhibited a larger change with time and position. A small osmotic gradient existed from branch to stem base under pre‐dawn conditions, and the osmotic gradient between upper stem and stem base was close to zero. The turgor in branches was significantly driven by xylem water potential, and the turgor loss point in branches was relatively close to daily minimum needle water potentials typically reported for Scots pine. Our results imply that xylem water potential considerably impacts the turgor pressure gradient driving phloem transport and that gravitation has a relatively large role in phloem transport in the stems of mature Scots pine trees. Phloem transport in conifers has been studied very little in field conditions. There is uncertainty especially about the relationships between phloem transport and whole tree physiological processes, for example, the effect of transpiration on the phloem turgor pressure, where the changing environmental conditions have a considerable role. We studied the dynamics of needle and inner bark osmotic potential at the whole tree level in mature trees and saplings and the preconditions of turgor pressure gradients against the theoretical background of phloem transport. Our results indicate that the xylem water potential and gravitation are considerably influencing the phloem transport, and similar patterns can be found both in mature trees and saplings.
    Subject(s): phloem transport ; turgor pressure ; osmolality ; conifer ; xylem water potential ; Water ; Xylem - physiology ; Picea - physiology ; Osmosis ; Pressure ; Fructose - metabolism ; Plant Stems - physiology ; Pinus sylvestris - physiology ; Osmolar Concentration ; Glucose - metabolism ; Environment ; Plant Bark - physiology ; Plant Leaves - physiology ; Erythromycin
    ISSN: 0140-7791
    E-ISSN: 1365-3040
    Source: Alma/SFX Local Collection
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  • 5
    Language: English
    In: Global change biology, 2016-11, Vol.22 (11), p.3804-3813
    Description: The interaction between xylem phenology and climate assesses forest growth and productivity and carbon storage across biomes under changing environmental conditions. We tested the hypothesis that patterns of wood formation are maintained unaltered despite the temperature changes across cold ecosystems. Wood microcores were collected weekly or biweekly throughout the growing season for periods varying between 1 and 13 years during 1998–2014 and cut in transverse sections for assessing the onset and ending of the phases of xylem differentiation. The data set represented 1321 trees belonging to 10 conifer species from 39 sites in the Northern Hemisphere and covering an interval of mean annual temperature exceeding 14 K. The phenological events and mean annual temperature of the sites were related linearly, with spring and autumnal events being separated by constant intervals across the range of temperature analysed. At increasing temperature, first enlarging, wall‐thickening and mature tracheids appeared earlier, and last enlarging and wall‐thickening tracheids occurred later. Overall, the period of wood formation lengthened linearly with the mean annual temperature, from 83.7 days at −2 °C to 178.1 days at 12 °C, at a rate of 6.5 days °C−1. April–May temperatures produced the best models predicting the dates of wood formation. Our findings demonstrated the uniformity of the process of wood formation and the importance of the environmental conditions occurring at the time of growth resumption. Under warming scenarios, the period of wood formation might lengthen synchronously in the cold biomes of the Northern Hemisphere.
    Subject(s): cell production ; cell differentiation ; secondary wall formation ; cambium ; conifers ; meristem ; growth ; climate change ; Trees ; Cold Temperature ; Plant Development ; Xylem ; Ecosystem ; Coniferophyta ; Seasons ; Biomes ; Environmental aspects ; Global temperature changes ; Cell differentiation ; Ecosystems ; Analysis ; Life Sciences ; Vegetal Biology
    ISSN: 1354-1013
    E-ISSN: 1365-2486
    Source: Alma/SFX Local Collection
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  • 6
    Language: English
    In: Annals of forest science., 2018-03, Vol.75 (1), p.1-11
    Description: Onset and cessation of radial and height increment of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) in southern Finland were independent phenomena. They both contributed to the increment period duration, which was a more crucial factor defining the magnitude of annual radial and height increment. Phenology of diameter and height increment is a critical component of growth, also contributing to damage and survival of trees.We quantified annual variation in intra-annual tracheid production and height increment of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.).The number of tracheids and the day of the year for the onset and cessation of tracheid production were monitored from microcores collected repeatedly during growing seasons 2001–2012 in southern Finland. Weekly height increment was also measured in an adjacent sapling stand in 2008–2012.The first tracheids in pine were found around mid-May and in spruce a week later. The cessation of the tracheid production occurred during the last week of August for both tree species. Increment onset and cessation were independent phenomena, both contributing to the magnitude of tracheid production via increment period duration, which appeared to be a more crucial factor defining the number of tracheids. Duration of the height increment period was also related to shoot length but the connection was less tight than the link between the duration of tracheid production and the number of tracheids. A thermal threshold around 100 d.d. (degree days) was found for the onset of radial increment. No single environmental factor triggered the cessation of tracheid production, but in some years, soil water availability appeared to play a role.The results indicate that extending growing seasons due to the climatic warming may increase growth in the Finnish forests.
    Subject(s): Life Sciences ; Environment, general ; Wood Science & Technology ; Phenology ; Forestry ; Forestry Management ; Xylogenesis ; Tracheid ; Tree Biology ; Pinus sylvestris ; Picea abies ; Trees ; Moisture content ; Pine ; Annual variations ; Soil water ; Environmental factors ; Pine trees ; Water availability ; Critical components
    ISSN: 1286-4560
    E-ISSN: 1297-966X
    Source: Alma/SFX Local Collection
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  • 7
    Language: English
    In: The New phytologist, 2018, Vol.218 (4), p.1383-1392
    Description: Trees scale leaf (AL) and xylem (AX) areas to couple leaf transpiration and carbon gain with xylem water transport. Some species are known to acclimate in AL: AX balance in response to climate conditions, but whether trees of different species acclimate in AL: AX in similar ways over their entire (continental) distributions is unknown. We analyzed the species and climate effects on the scaling of AL vs AX in branches of conifers (Pinus sylvestris, Picea abies) and broadleaved (Betula pendula, Populus tremula) sampled across a continental wide transect in Europe. Along the branch axis, AL and AX change in equal proportion (isometric scaling: b ˜ 1) as for trees. Branches of similar length converged in the scaling of AL vs AX with an exponent of b = 0.58 across European climates irrespective of species. Branches of slow-growing trees from Northern and Southern regions preferentially allocated into new leaf rather than xylem area, with older xylem rings contributing to maintaining total xylem conductivity. In conclusion, trees in contrasting climates adjust their functional balance between water transport and leaf transpiration by maintaining biomass allocation to leaves, and adjusting their growth rate and xylem production to maintain xylem conductance.
    Subject(s): Climate change ; Plant architecture ; Sapwood ; Xylem ; Allocation ; Structural balance ; Functional balance ; Leaf area ; xylem ; allocation ; structural balance ; sapwood ; functional balance ; plant architecture ; leaf area ; climate change ; Analysis ; Global temperature changes ; Electric properties ; Life Sciences ; Environmental Sciences
    ISSN: 0028-646X
    E-ISSN: 1469-8137
    Source: Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals
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  • 8
    Language: English
    In: Molecules (Basel, Switzerland), 2020-06-26, Vol.25 (12), p.2952
    Description: To understand the positional and temporal defense mechanisms of coniferous tree bark at the tissue and cellular levels, the phloem topochemistry and structural properties were examined after artificially induced bark defense reactions. Wounding and fungal inoculation with of spruce bark were carried out, and phloem tissues were frequently collected to follow the temporal and spatial progress of chemical and structural responses. The changes in (+)-catechin, (-)-epicatechin, stilbene glucoside, and resin acid distribution, and accumulation patterns within the phloem, were mapped using time-of-flight secondary ion mass spectrometry (cryo-ToF-SIMS), alongside detailed structural (LM, TEM, SEM) and quantitative chemical microanalyses of the tissues. Our results show that axial phloem parenchyma cells of Norway spruce contain (+)-catechins, the amount of which locally increases in response to fungal inoculation. The preformed, constitutive distribution and accumulation patterns of (+)-catechins closely follow those of stilbene glucosides. Phloem phenolics are not translocated but form a layered defense barrier with oleoresin compounds in response to pathogen attack. Our results suggest that axial phloem parenchyma cells are the primary location for (+)-catechin storage and synthesis in Norway spruce phloem. Chemical mapping of bark defensive metabolites by cryo-ToF-SIMS, in addition to structural and chemical microanalyses of the defense reactions, can provide novel information on the local amplitudes and localizations of chemical and structural defense mechanisms and pathogen-host interactions of trees.
    Subject(s): Microscopy, Electron, Transmission ; Gas Chromatography-Mass Spectrometry ; Picea - microbiology ; Spectrometry, Mass, Secondary Ion ; Stilbenes - analysis ; Glucosides - analysis ; Plant Diseases - microbiology ; Plant Bark - chemistry ; Tissue Distribution ; Catechin - analysis ; Ascomycota - pathogenicity ; Plant Extracts - metabolism ; Picea - chemistry ; Phloem - chemistry ; tissue-specific chemical mapping ; morphological changes ; fungal inoculation ; defense response ; tannins ; axial phloem parenchyma ; phenolics
    ISSN: 1420-3049
    E-ISSN: 1420-3049
    Source: Academic Search Ultimate
    Source: PubMed Central
    Source: DOAJ Directory of Open Access Journals - Not for CDI Discovery
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  • 9
    Language: English
    In: Molecules (Basel, Switzerland), 2020-01-28, Vol.25 (3), p.567
    Description: Bark of Norway spruce and Scots pine trees contain large amounts of condensed tannins. Tannins extracted with hot water could be used in different applications as they possess antioxidative and antimicrobial activities. The use of bark tannins as e.g., food preservatives calls for increases in our knowledge of their antioxidative activities when applied in foodstuffs. To assess the ability of bark tannins to prevent lipid oxidation, hot water extracts were evaluated in a liposome model. Isolated tannins were also applied in dry-cured, salty meat snacks either as liquid extracts or in dry-powder form. Consumer acceptance of the snacks was tested by a sensory evaluation panel where outlook, odor, taste, and structure of the snacks were evaluated and compared to a commercial product without tannin ingredients. Our results show that conifer bark tannin-rich extracts have high capacity to prevent lipid oxidation in the liposome model. The efficacies of pine and spruce bark extracts were ten to hundred folds higher, respectively, than those of phenolic berry extracts. The bark extracts did not significantly influence the odor or taste of the meat snacks. The findings indicate that bark extracts may be used as sustainable food ingredients. However, more research is needed to verify their safety.
    Subject(s): flavor ; phenolic compounds ; preservative use ; condensed tannins ; antioxidative ; aroma ; bark side-stream
    ISSN: 1420-3049
    E-ISSN: 1420-3049
    Source: Academic Search Ultimate
    Source: PubMed Central
    Source: DOAJ Directory of Open Access Journals - Not for CDI Discovery
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  • 10
    Language: English
    In: Plant physiology (Bethesda), 2016-10-01, Vol.172 (2), p.913-928
    Description: Phenolic stilbene glucosides (astringin, isorhapontin, and piceid) and their aglycons commonly accumulate in the phloem of Norway spruce ( ). However, current knowledge about the localization and accumulation of stilbenes within plant tissues and cells remains limited. Here, we used an innovative combination of novel microanalytical techniques to evaluate stilbenes in a frozen-hydrated condition (i.e. in planta) and a freeze-dried condition across phloem tissues. Semiquantitative time-of-flight secondary ion-mass spectrometry imaging in planta revealed that stilbenes were localized in axial parenchyma cells. Quantitative gas chromatography analysis showed the highest stilbene content in the middle of collapsed phloem with decreases toward the outer phloem. The same trend was detected for soluble sugar and water contents. The specimen water content may affect stilbene composition; the glucoside-to-aglycon ratio decreased slightly with decreases in water content. Phloem chemistry was correlated with three-dimensional structures of phloem as analyzed by microtomography. The outer phloem was characterized by a high volume of empty parenchyma, reduced ray volume, and a large number of axial parenchyma with porous vacuolar contents. Increasing porosity from the inner to the outer phloem was related to decreasing compactness of stilbenes and possible secondary oxidation or polymerization. Our results indicate that aging-dependent changes in phloem may reduce cell functioning, which affects the capacity of the phloem to store water and sugar, and may reduce the defense potential of stilbenes in the axial parenchyma. Our results highlight the power of using a combination of techniques to evaluate tissue- and cell-level mechanisms involved in plant secondary metabolite formation and metabolism.
    Subject(s): BIOCHEMISTRY AND METABOLISM ; Phloem - anatomy & histology ; Gas Chromatography-Mass Spectrometry ; Stilbenes - analysis ; Freeze Drying ; Imaging, Three-Dimensional - methods ; Water - metabolism ; Glucosides - analysis ; Stilbenes - metabolism ; Phloem - cytology ; X-Ray Microtomography - methods ; Glucosides - metabolism ; Microscopy, Electron, Scanning - methods ; Picea - chemistry ; Picea - anatomy & histology ; Spectrometry, Mass, Secondary Ion - methods ; Picea - cytology ; Phloem - chemistry ; Physiological aspects ; Porosity ; Metabolites ; Mass spectrometry
    ISSN: 0032-0889
    E-ISSN: 1532-2548
    Source: American Society of Plant Biologists
    Source: JSTOR Life Sciences
    Source: Hellenic Academic Libraries Link
    Source: JSTOR Ecology & Botany II
    Source: PubMed Central
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