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John N. King - One of the best experts on this subject based on the ideXlab platform.
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constitutive defenses and damage in sitka spruce progeny obtained from crosses between white pine weevil resistant and susceptible parents
Forestry, 2012Co-Authors: Xoaquín Moreira, René I. Alfaro, John N. KingAbstract:Summary Attack by the white pine weevil has notably reduced Sitka spruce productivity in British Columbia (BC) (Canada) and western US. By the 1970s, the BC Ministry of Forests established provenance trials of Sitka spruce with the objective of detecting usable genetic resistance to weevil. These early trials reported significant weevil resistance and allowed the production of the first (F1) controlled-cross progeny generation with demonstrable weevil resistance (R) or susceptibility (S). This study reports results of the screening for weevil resistance and the levels of constitutive defenses of this F1 Sitka spruce progeny. Progeny from resistant parents (R × R progeny) sustained significantly fewer weevil attacks than progeny from susceptible parents (S × S progeny) or progeny with one resistant and one susceptible parent (R × S progeny). Individual and family heritability estimates of the weevil resistance were 0.5 and 0.9, respectively. Constitutive defenses, measured by resin canal and sclereid cell density in the cortex, were significantly higher in R × R progeny than in R × S or S × S progeny. We observed a negative correlation between the percentage of trees attacked in each cross and the average density of the resin canals or sclereid cells for each cross.
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resistance of sitka spruce picea sitchensis bong carr to white pine weevil pissodes strobi peck characterizing the bark defence mechanisms of resistant populations
Forestry, 2011Co-Authors: John N. King, René I. Alfaro, Moraia Grau Lopez, Lara Van AkkerAbstract:Summary It has long been known that strong expressions of resistance to the white pine weevil ( Pissodes strobi Peck) exist in certain Sitka spruce ( Picea sitchensis (Bong.) Carr.) populations, particularly among trees originating from the Fraser Valley and the Qualicum area of British Columbia (BC). In this paper , we characterize how resistance is manifested in these known resistant populations. Specifi cally, using cloned individuals, we investigated resistant traits associated with repellency , constitutive resin canals (CRC) and sclereid or stone cells. Results indicate signifi cant population differences in the level of these traits between these two populations and susceptible populations. Fraser Valley populations had four times the sclereid density of susceptible populations. Although the Big Qualicum (East Vancouver Island) population had the same high resistance as the Haney (Fraser Valley) population, it was expressed primarily through increased CRC. Sclereid cell density had the strongest correlation to weevil attack followed by CRC. We discuss pathways by which two distinct resistant populations may have developed in this high weevil hazard region of south - west BC.
Ewa Cholewa - One of the best experts on this subject based on the ideXlab platform.
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x ray μct imaging technique reveals corm microstructures of an arctic boreal cotton sedge eriophorum vaginatum
Journal of Structural Biology, 2010Co-Authors: Sarah J Bogart, Graeme Spiers, Ewa CholewaAbstract:X-ray computed tomography (CT), a non-destructive imaging technique, has recently been effectively applied to botanical research. In this study an X-ray μCT technique was developed to allow for anatomical study of the overwintering corms of Eriophorum vaginatum, an ecologically important sedge species in arctic tussock-tundra and boreal peatlands. Using a GE Medical MS8X-130 X-ray μCT scanner, optimal imaging parameters included scanning isolated corms at 80 kVp and 100 μA with a 3500 ms exposure time and an isotropic voxel size of 10 μm. A Gaussian blur image filter with a blur radius (σ) of two pixels was applied to the optimal dataset to improve visual detection and contrast of tissues while removing 99.2% of image noise. Using the developed X-ray μCT technique several undocumented anatomical characteristics of the corm were identified including the vascular connection between a parent corm and branching cormel and the 3D shape of sclereid clusters. The 3D structure of sclereid clusters was determined whereby the perimeter of their lance shape is greatly reinforced by Sclereids with thicker secondary cell walls as compared to those of the interior of the cluster. The structure of sclereid clusters and their association with leaf traces suggests they may be stabilizing the corm-leaf connection to protect vascular tissues from physical damage. The proposed X-ray μCT technique is an excellent tool for determination of the 3D structure of E. vaginatum corms and may be used to detect alterations in tissue structure and chemistry in response to environmental change in this and other Cyperaceous species.
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the unusual vascular structure of the corm of eriophorum vaginatum implications for efficient retranslocation of nutrients
Journal of Experimental Botany, 2004Co-Authors: Ewa Cholewa, Marilyn GriffithAbstract:Eriophorum spp. are abundant perennial graminoids in the Arctic tundra and boreal peatlands. Because ecological studies indicated that some plants are unusually productive on infertile and cold sites, the anatomy of the overwintering corms of Eriophorum vaginatum (L.) and Eriophorum scheuchzeri (Hoppe) were examined to determine their involvement in nutrient uptake and storage. Components of the long-distance transport pathways were identified within the plants by using histochemical techniques and transport of apoplastic and symplastic dyes. E. scheuchzeri produced a rhizome that consisted mainly of storage parenchyma cells within which collateral vascular bundles were centrally located and arranged in a circle. By contrast, E. vaginatum developed a ring of horizontally arranged xylem and phloem, in addition to axial amphivasal vascular bundles leading to the leaves, all of which were bordered by transfer cells. As shown by the transport of fluorescein in the phloem and Safranine O in the xylem, each axial bundle and adventitious root contacted the horizontal ring of vascular tissues so that solutes from one vascular bundle were translocated into the vascular ring and circulated to another vascular bundle and/or to the roots. In addition, special groups of Sclereids that functioned in both phloem and xylem transport were found at the base of the leaf traces and within junctions of senescing roots. These Sclereids were named ‘vascular sclerenchyma’ and it was hypothesized that they provide a moving end for the vascular system because the corm dies progressively from the distal end as it grows upward from the apical meristem. It was concluded that this unusual vascular system of E. vaginatum is efficient in recycling nutrients internally, which may account for its competitive advantage in infertile and cold sites.
Peter A. Stone - One of the best experts on this subject based on the ideXlab platform.
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The utility of Nymphaeaceae Sclereids in paleoenvironmental research
Review of Palaeobotany and Palynology, 2012Co-Authors: Robby R. Marrotte, Gail L. Chmura, Peter A. StoneAbstract:Abstract As entomophilous plants, water lilies (Nymphaea) and spatterdocks (Nuphar) have low pollen production, thus can be under represented in the sediment record. These macrophytes produce distinctly shaped sclerenchyma tissue referred to as stone-cells, trichoSclereids, astroSclereids or simply Sclereids. This study examines the utility of using Sclereids from two common species from the Nymphaeaceae Family as an alternative to their pollen. Histological studies of fresh tissues of Nymphaea odorata and Nuphar lutea show that each has distinct Sclereids, but there has been confusion in the terminology used to designate their morphology. Some reports have referred to Nymphaeaceae Sclereids as trichoSclereids, but our histological studies show that the cells are more appropriately classified as polyramous, astroSclereids, libroSclereids or rhizoSclereids. Tissues from both species were treated using HCL, KOH, acetolysis and HF. We found that only the Sclereids from N. lutea survived chemical treatments in a detectable form, indicating that Sclereids from N. lutea can be a useful indicator of presence while the chance of observing Sclereids from N. odorata in pollen preparations is very low, severely limiting the utility of the latter as a paleoecological indicator. Another limitation to using Sclereids as a proxy is that they originate from tissues that require extended acetolysis treatments for release from the matrix. Finally, we examined sclereid abundance in sediments from a slough in the Florida Everglades, USA to determine if abundance of Nymphaeaceae Sclereids correlates with Nymphaeaceae pollen and we find no significant correlation. Additional analyses are required to determine if empirical relationships exist amongst plant populations, pollen, Sclereids and environmental conditions. A clear report of chemical treatments used and processing times are critical to verify results of studies utilizing Sclereids.
Beat Ernst Leuenberger - One of the best experts on this subject based on the ideXlab platform.
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noteworthy idioblastic Sclereids in the stems of eulychnia cactaceae
American Journal of Botany, 1997Co-Authors: Reto Nyffeler, Urs Eggli, Beat Ernst LeuenbergerAbstract:Stems of Eulychnia (a genus of six to nine species of candelabriform or arborescent cacti) have a parenchymatic cortex with two distinct regions. The outer chlorenchymatic layer is characterized by a conspicuous parallel striping, whereas the inner cortex region devoid of chlorophyll has a coarsely granular aspect. Stem samples from nine accessions, collected in the field or taken from cultivation, were studied from resin-embedded microtome sections and maceration. Two different forms of lignified Sclereids were found dispersed in the cortex and the pith. The Sclereids of the outer palisade-like cortex layer are distinctly elongated and strictly oriented at right angle to the stem surface, whereas those of the inner cortex and pith are globular or subglobular and conspicuously enlarged compared with the surrounding parenchyma cells. The ontogeny of the Sclereids was studied from stem samples of different ages. Formation of the secondary cell walls starts only after cell growth is completed. A screening of numerous South American cacti for the presence of idioblastic Sclereids showed that these structures are unique for the genus Eulychnia. Finally, functional aspects of the Sclereids are shortly discussed. It is assumed that the Sclereids contribute to the mechanical support and reinforcement of the plants. Eulychnia is a small genus of candelabriform or arborescent cacti (Fig 1.). It is confined to the coastal Atacama desert of Chile and Peru, extending from near Los Vilos in central Chile (31 8 509 S) to Chala in southern Peru (158 509 S), at an altitude from sea level to ;1250 m. Eulychnia comprises six to nine species (Ritter, 1980, 1981; Barthlott and Hunt, 1993). Species delimitation is not yet sufficiently resolved, and especially the northern taxa E. barquitensis, E. iquiquensis, E. saint-pieana, E. morromorenoensis, E. aricensis(all from Chile), and E. ritteri (from Peru) need further study. Among the southern taxa, hybridization and introgression have been observed between E. breviflora and E. acida (Ritter, 1980; Leuenberger and Eggli, unpublished data). The genus was established by Philippi (1860) with two species, E. breviflora and E. castanea. The latter was segregated as Philippicereus by Backeberg (1942) based on its spiny pericarpel, but is now commonly united again with Eulychnia (Ritter, 1980; Barthlott and Hunt, 1993). Schumann (1903) treated the two taxa under Cereus, noting that Eulychnia is (translated) ‘‘a completely unnatural genus . ... whose main character—the woolly-hairy ovary—is not even present in all described species.’’ Subsequent authors have had no doubt about the natural circumscription of the genus, and Ritter (1980) expressed the view that it represents a well-characterized
René I. Alfaro - One of the best experts on this subject based on the ideXlab platform.
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constitutive defenses and damage in sitka spruce progeny obtained from crosses between white pine weevil resistant and susceptible parents
Forestry, 2012Co-Authors: Xoaquín Moreira, René I. Alfaro, John N. KingAbstract:Summary Attack by the white pine weevil has notably reduced Sitka spruce productivity in British Columbia (BC) (Canada) and western US. By the 1970s, the BC Ministry of Forests established provenance trials of Sitka spruce with the objective of detecting usable genetic resistance to weevil. These early trials reported significant weevil resistance and allowed the production of the first (F1) controlled-cross progeny generation with demonstrable weevil resistance (R) or susceptibility (S). This study reports results of the screening for weevil resistance and the levels of constitutive defenses of this F1 Sitka spruce progeny. Progeny from resistant parents (R × R progeny) sustained significantly fewer weevil attacks than progeny from susceptible parents (S × S progeny) or progeny with one resistant and one susceptible parent (R × S progeny). Individual and family heritability estimates of the weevil resistance were 0.5 and 0.9, respectively. Constitutive defenses, measured by resin canal and sclereid cell density in the cortex, were significantly higher in R × R progeny than in R × S or S × S progeny. We observed a negative correlation between the percentage of trees attacked in each cross and the average density of the resin canals or sclereid cells for each cross.
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resistance of sitka spruce picea sitchensis bong carr to white pine weevil pissodes strobi peck characterizing the bark defence mechanisms of resistant populations
Forestry, 2011Co-Authors: John N. King, René I. Alfaro, Moraia Grau Lopez, Lara Van AkkerAbstract:Summary It has long been known that strong expressions of resistance to the white pine weevil ( Pissodes strobi Peck) exist in certain Sitka spruce ( Picea sitchensis (Bong.) Carr.) populations, particularly among trees originating from the Fraser Valley and the Qualicum area of British Columbia (BC). In this paper , we characterize how resistance is manifested in these known resistant populations. Specifi cally, using cloned individuals, we investigated resistant traits associated with repellency , constitutive resin canals (CRC) and sclereid or stone cells. Results indicate signifi cant population differences in the level of these traits between these two populations and susceptible populations. Fraser Valley populations had four times the sclereid density of susceptible populations. Although the Big Qualicum (East Vancouver Island) population had the same high resistance as the Haney (Fraser Valley) population, it was expressed primarily through increased CRC. Sclereid cell density had the strongest correlation to weevil attack followed by CRC. We discuss pathways by which two distinct resistant populations may have developed in this high weevil hazard region of south - west BC.