Initiation and development of latent infections by Rhabdocline parkeri on Douglas-fir

1987 ◽  
Vol 65 (12) ◽  
pp. 2614-2621 ◽  
Author(s):  
Jeffrey K. Stone
Keyword(s):  
Epidermal Cell ◽  
Douglas Fir ◽  
Latent Infections ◽  
Saprophytic Fungi ◽  
Needle Age ◽  
Direct Microscopy ◽  
Quantitative Estimates ◽  
Needle Senescence ◽  
In Cells

Quantitative estimates of frequencies of latent infections by Rhabdocline parkeri Sherw. on Douglas-fir were obtained by direct microscopy of cleared needles from three half-sib trees. The infections are intracellular and are confined to a single epidermal cell until the onset of needle senescence, a period of 2 – 5 years. Infection frequencies varied widely among trees but increase logarithmically with needle age on all three trees. Differences in infection frequencies among trees were not demonstrably related to levels of infestation by Contarinia spp., a needle-galling dipteran. Active colonization of the needle resumes at the onset of needle senescence, beginning with the production of haustoria in cells adjacent to the original infection sites. Rapid colonization of the needle and sporulation of R. parkeri coincide with needle abscission, occurring before substantial colonization of the needles by saprophytic fungi. Saprophytic fungi colonized needles rapidly following abscission, but R. parkeri was recoverable in culture from needles up to 35 days after abscission.

Fine structure of latent infections by Rhabdocline parkeri on Douglas-fir, with observations on uninfected epidermal cells

1988 ◽  
Vol 66 (1) ◽  
pp. 45-54 ◽  
Author(s):  
Jeffrey K. Stone
Keyword(s):  
Epidermal Cell ◽  
Condensed Tannins ◽  
Douglas Fir ◽  
Epidermal Cells ◽  
Central Vacuole ◽  
Direct Penetration ◽  
Large Central Vacuole ◽  
Epidermal Cell Wall ◽  
Intracellular Infections ◽  
Needle Senescence

Rhabdocline parkeri Sherwood-Pike, Stone, & Carroll, an endophyte of Douglas-fir, infects healthy foliage by direct penetration of the host epidermal cell wall. Penetration is accomplished by a very fine penetration hypha. Intracellular infections are established in a single epidermal cell and result in the death of the cell. Haustoria lacking neckbands are produced from the intracellular hyphae at the onset of needle senescence. The intracellular hyphae contain large quantities of stored lipid and numerous mitochondria and peroxisomes. Although not growing, the hyphae appear to be metabolically active. Douglas-fir epidermal cells are alive at maturity and contain rudimentary chloroplasts. Small quantities of lipids and starch are present in the healthy epidermal cells. The large central vacuole of the epidermal cells contains primarily condensed tannins and tannin precursors.

scholarly journals Incidence and Impact of Swiss Needle Cast in Forest Plantations of Douglas-fir in Coastal Oregon

Plant Disease ◽  
2000 ◽  
Vol 84 (7) ◽  
pp. 773-778 ◽  
Author(s):  
E. M. Hansen ◽  
J. K. Stone ◽  
B. R. Capitano ◽  
P. Rosso ◽  
W. Sutton ◽  
...  
Keyword(s):  
Severe Disease ◽  
Tree Height ◽  
Aerial Survey ◽  
Douglas Fir ◽  
Permanent Plots ◽  
Forest Plantations ◽  
Needle Age ◽  
Needle Cast ◽  
Needle Retention ◽  
Swiss Needle Cast

An epidemic of Swiss needle cast, caused by the ascomycete Phaeocryptopus gaeumannii, is causing defoliation and growth reductions in Douglas-fir forest plantations along the Oregon Coast. The area of symptomatic plantations has been monitored annually since 1996 by aerial survey; in spring 1999, 119,500 ha were affected. Pathogen and symptom development have also been monitored on nine permanent plots in stands of differing disease severity. Infection levels and symptom severity are greatest in low elevation plantations close to the coast. In areas of severe disease, trees retain only current year needles. Defoliation is proportional to the number of stomata occluded by pseudothecia of the fungus, with needles being shed when about 50% of stomata are occupied, regardless of needle age. Fungus sporulation and premature needle abscission are greatest on the upper branches of trees. Annual application of fungicides increases needle retention significantly. Tree height and diameter growth and total tree volume are reduced by disease, and tree volume is significantly correlated with needle retention on our plot trees. The epidemic continues to be most severe in Douglas-fir plantations established on sites where Sitka spruce and western hemlock or red alder predominated in earlier times.

scholarly journals Variation in specific needle area of old-growth Douglas-fir in relation to needle age, within-crown position and epicormic shoot production

2002 ◽  
Vol 22 (1) ◽  
pp. 31-40 ◽  
Author(s):  
H. Ishii ◽  
E. D. Ford ◽  
M. E. Boscolo ◽  
A. C. Manriquez ◽  
M. E. Wilson ◽  
...  
Keyword(s):  
Douglas Fir ◽  
Old Growth ◽  
Needle Age ◽  
Crown Position ◽  
Shoot Production ◽  
Epicormic Shoot

scholarly journals The effects of cold and colchicine on mitosis in the newt

1943 ◽  
Vol 131 (864) ◽  
pp. 258-271 ◽  
Keyword(s):  
Epidermal Cell ◽  
Cold Treatment ◽  
Colchicine Treatment ◽  
Epidermal Cells ◽  
Abnormal Development ◽  
Complete Suppression ◽  
Two Agents ◽  
Cell Processes ◽  
Surface Changes ◽  
In Cells

The application of cold or colchicine to dividing epidermal cells of the newt larva produces by similar means an arrest of mitosis at metaphase. The cells respond to both agents by complete suppression or by abnormal development of the spindle. The various types of abnormal spindle which are produced can be described in terms of the complete or incomplete inactivation of centromeres, centrosomes or both. Spermatogonia and spermatocytes, unlike the epidermal cells, invariably show complete spindle suppression during cold treatment. The more obvious differences between the effects of the two agents are due ( a ) to the greater severity of spindle suppression produced by colchicine, and ( b ) to the slowing up of all cell processes produced by cold. Thus while both treatments lead to the production of relapsed tetraploid cells, these occur more commonly after colchicine treatment. The untreated epidermal cell swells up during anaphase. This swelling is exaggerated in cells held at metaphase under the action of cold or colchicine. The inactivation effects can be described in terms of a tactoid theory, as due to surface changes in centrosomes or centromeres which prevent them orientating or breaking down spindle molecules.

Ten-year growth and mortality in young Douglas-fir stands experiencing a range in Swiss needle cast severity

2011 ◽  
Vol 41 (10) ◽  
pp. 2064-2076 ◽  
Author(s):  
Douglas A. Maguire ◽  
Douglas B. Mainwaring ◽  
Alan Kanaskie
Keyword(s):  
Disease Severity ◽  
Growth Period ◽  
Douglas Fir ◽  
Permanent Plots ◽  
Annual Increment ◽  
Needle Age ◽  
Needle Cast ◽  
Needle Retention ◽  
Swiss Needle Cast ◽  
Annual Mortality

Swiss needle cast, a foliar disease caused by the Ascomycete Phaeocryptopus gaeumannii (T. Rohde) Petr., continues to afflict Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) in north coastal Oregon. Permanent plots were installed in 1998 to assess growth impacts and monitor disease severity. Gross periodic annual increment was measured for three 2-year growth periods and one 4-year growth period and ranged from 0.37 to 31.74 m3·ha–1·year–1. Foliage retention, defined as the average number of annual needle age classes held by a tree, was also estimated as an index of disease severity. Assuming negligible losses in stands with maximum needle retention (approximately 3.9 years), growth losses in net periodic annual increment reached slightly over 50% in stands with the lowest needle retention (approximately 1 year). Mixed-effects regression models supported a consistent relationship between foliage retention and both gross and net periodic annual increment among the four growth periods. Periodic annual mortality ranged from 0 to 19.12 m3·ha–1·year–1 but was not significantly influenced by Swiss needle cast as measured by average foliage retention. Minimum and maximum foliage retention has fluctuated annually from 1998 to 2008 on the permanent plots, but growth losses at a given level of foliage retention appear to have remained stable. Estimated growth losses are similar to those reported for comparable levels of defoliation by other agents.

EFFECT OF SALT CONCENTRATION ON THE MORPHOLOGY AND CHEMICAL COMPOSITION OF MICROCOCCUS HALODENITRIFICANS

1959 ◽  
Vol 5 (1) ◽  
pp. 25-35 ◽  
Author(s):  
I. Takahashi ◽  
N. E. Gibbons
Keyword(s):  
Growth Medium ◽  
Salt Concentration ◽  
Osmotic Shock ◽  
Salt Content ◽  
Diaminopimelic Acid ◽  
Wall Material ◽  
Cell Wall Material ◽  
Quantitative Estimates ◽  
Nitrogen Ratio ◽  
In Cells

Cells of Micrococcus halodenitrificans grown in media containing more than 0.7 M sodium chloride appeared normal microscopically, but in 0.6 M salt many cells were swollen and in 0.55 M salt most cells were swollen or ruptured. The swollen cells were sensitive to osmotic shock. Calcium or magnesium prevented the cells from swelling and extended the lower limit of growth from 0.55 to 0.3 M salt. Walls of normal cells contained 6 carbohydrates and 16 amino acids. Qualitative chromatographic analyses indicated that cells grown in 0.55 M salt contained less tyrosine, diaminopimelic acid, and an unknown ninhydrin-positive, cytoplasmic component than cells grown in 1.0 M salt. Quantitative estimates indicated that diaminopimelic acid/nitrogen ratio in cells decreased gradually from 0.25 to 0.16 as the salt content of the growth medium decreased from 1.0 to 0.55 M, but that it decreased to 0.003 in cells grown in 0.3 M salt plus calcium. The results suggest that less cell wall material is produced as the salt concentration in the growth medium is decreased and that calcium has a protective effect on the weakened cells or protoplasts.

The effects of host genotype, growth rate, and needle age on the distribution of a mutualistic, endophytic fungus in Douglas-fir plantations

1988 ◽  
Vol 18 (5) ◽  
pp. 601-605 ◽  
Author(s):  
Dennis Todd
Keyword(s):  
Growth Rate ◽  
Endophytic Fungus ◽  
Detailed Examination ◽  
Douglas Fir ◽  
Host Genotype ◽  
Needle Age ◽  
Insecticidal Toxins

Two young plantations of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) were examined for the presence of a symptomless endophytic fungus, Meriaparkeri Sherwood-Pike (Hemiphacideaceae). This fungus occurred in the needles of nearly every tree examined, with infection frequencies increasing with the age of the needle. Previous reports have asserted that M. parkeri is a mutualist that produces insecticidal toxins. The maternal parentage of the trees and age of the needles were highly significant predictors of infection frequencies. A detailed examination of two families of trees revealed that infection frequencies differed between sites and were positively correlated with the height of the host. Mutualism and microhabitat effects are discussed.

Some Results of the Spectroscopic Study of Four Close Binary Systems of Early Spectral Types

1965 ◽  
Vol 5 ◽  
pp. 120-130
Author(s):  
T. S. Galkina
Keyword(s):  
Spectroscopic Study ◽  
Spectral Type ◽  
Spectroscopic Investigation ◽  
Binary Systems ◽  
Quantitative Information ◽  
Close Binary ◽  
Physical Parameters ◽  
Absorption And Emission ◽  
Close Binary Systems ◽  
Quantitative Estimates

It is necessary to have quantitative estimates of the intensity of lines (both absorption and emission) to obtain the physical parameters of the atmosphere of components.Some years ago at the Crimean observatory we began the spectroscopic investigation of close binary systems of the early spectral type with components WR, Of, O, B to try and obtain more quantitative information from the study of the spectra of the components.

The Resolution and Contrast in Biological Sections Determined by Inelastic and Elastic Scattering

1973 ◽  
Vol 31 ◽  
pp. 224-225
Author(s):  
D. L. Misell
Keyword(s):  
Electron Microscopy ◽  
Adverse Effect ◽  
Elastic Scattering ◽  
Inelastic Scattering ◽  
Amorphous Carbon ◽  
Polymeric Materials ◽  
Chromatic Aberration ◽  
Image Resolution ◽  
Quantitative Estimates ◽  
Elastic Ratio

In the electron microscopy of biological sections the adverse effect of chromatic aberration on image resolution is well known. In this paper calculations are presented for the inelastic and elastic image intensities using a wave-optical formulation. Quantitative estimates of the deterioration in image resolution as a result of chromatic aberration are presented as an alternative to geometric calculations. The predominance of inelastic scattering in the unstained biological and polymeric materials is shown by the inelastic to elastic ratio, I/E, within an objective aperture of 0.005 rad for amorphous carbon of a thickness, t=50nm, typical of biological sections; E=200keV, I/E=16.

Cytoplasmic Tubules in Cells Infected with Laryngotracheitis Virus

1969 ◽  
Vol 27 ◽  
pp. 376-377
Author(s):  
A. M. Watrach
Keyword(s):  
Tissue Culture ◽  
Small Proportion ◽  
Chicken Embryo ◽  
Culture Cells ◽  
Tissue Culture Cells ◽  
Morphologic Characteristics ◽  
Infectious Laryngotracheitis ◽  
Laryngotracheitis Virus ◽  
In Cells

During a study of the development of infectious laryngotracheitis (LT) virus in tissue culture cells, unusual tubular formations were found in the cytoplasm of a small proportion of the affected cells. It is the purpose of this report to describe the morphologic characteristics of the tubules and to discuss their possible association with the development of virus.The source and maintenance of the strain of LT virus have been described. Prior to this study, the virus was passed several times in chicken embryo kidney (CEK) tissue culture cells.

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