Ultrastructural cell wall modifications in secondary xylem of American elm surviving the acute stage of Dutch elm disease: fibres

1981 ◽  
Vol 59 (12) ◽  
pp. 2425-2438 ◽  
Author(s):  
G. B. Ouellette
Keyword(s):  
Cell Wall ◽  
Tension Wood ◽  
Secondary Xylem ◽  
Acute Stage ◽  
Dutch Elm Disease ◽  
Tubular Structures ◽  
Ulmus Americana ◽  
American Elm ◽  
Innermost Layer ◽  
Host Parasite

Various ultrastructural cell wall modifications of fibres have been observed in artificially or naturally infected American elm (Ulmus americana L.) trees surviving the acute stage of the Dutch elm disease caused by Ceratocystis ulmi (Buism.) C. Moreau. Bands of fibres with gelatinous (SG) layers characteristic of tension wood are frequent in or near invaded tissues; similar layers are also present sometimes in cells identifiable as parenchyma. The SG layer is often different from that observed in healthy trees. Masses or bands of dense material are present which often extend perpendicular as tubular structures to the plasmalemma location. Also, orientation of fibrils in such layers may be disordinate. One or more additional lignified-like layers alternating with additional SG-like or other opaque layers may occur inside the first SG layer. The innermost layer in these cases is often lamellate.Small intracellular locules delimited by one or two wall layers also occur in other cells.The possible significance of these observations in host–parasite relationships of the disease is briefly discussed.

The Microscopy of Compatibility and Incompatibility in Ulmus

1985 ◽  
Vol 43 ◽  
pp. 504-505
Author(s):  
B. L. Redmond ◽  
Christopher F. Bob
Keyword(s):  
Dutch Elm Disease ◽  
Economic Losses ◽  
Hybrid Progeny ◽  
Ulmus Pumila ◽  
Ulmus Americana ◽  
American Elm ◽  
Asian Species ◽  
Ulmus Parvifolia ◽  
Initial Appearance ◽  
Chinese Elm

The American Elm (Ulmus americana L.) has been plagued by Dutch Elm Disease (DED), a lethal disease caused by the fungus Ceratocystis ulmi (Buisman) c. Moreau. Since its initial appearance in North America around 1930, DED has wrought inexorable devastation on the American elm population, triggering both environmental and economic losses. In response to the havoc caused by the disease, many attempts have been made to hybridize U. americana with a few ornamentally less desirable, though highly DED resistant, Asian species (mainly the Siberian elm, Ulmus pumila L., and the Chinese elm Ulmus parvifolia Jacq.). The goal is to develop, through breeding efforts, hybrid progeny that display the ornamentally desirable characteristics of U. americana with the disease resistance of the Asian species. Unfortunately, however, all attempts to hybridize U. americana have been prevented by incompatibility. Only through a firm understanding of both compatibility and incompatibility will it be possible to circumvent the incompatibility and hence achieve hybridization.

scholarly journals Evaluation of 19 American Elm Clones for Tolerance to Dutch Elm Disease

2005 ◽  
Vol 23 (1) ◽  
pp. 21-24 ◽  
Author(s):  
A. M. Townsend ◽  
S. E. Bentz ◽  
L. W. Douglass
Keyword(s):  
Block Design ◽  
Dutch Elm Disease ◽  
Stem Cuttings ◽  
Ulmus Americana ◽  
American Elm ◽  
Foliar Symptoms ◽  
Randomized Block Design ◽  
New Harmony ◽  
Crown Dieback ◽  
Valley Forge

Abstract Rooted stem cuttings of 19 American elm (Ulmus americana L.) cultivars and selections, and rooted cuttings of two non-American elm selections, U. carpinifolia Gleditsch 51 and 970 (U. glabra Huds. x (U. wallichiana Planch. x U. carpinifolia)), along with a group of American elm seedlings, were planted in a randomized block design. When the trees were nine years old, they were inoculated with a mixed spore suspension of Ophiostoma ulmi (Buisman) C. Nannf. and Ophiostoma novo-ulmi Brasier, the causal fungi for Dutch elm disease (DED). Analyses of variance showed highly significant variation among clones in foliar symptoms 4 weeks after inoculation and in crown dieback one and two years after inoculation. After two years, 13 of the American clones showed significantly less dieback than the American elm seedlings, and 18 American clones showed significantly less injury than a randomly chosen, unselected American elm clone, 57845. The American clones with the most DED-tolerance were cultivars ‘Valley Forge,’ ‘Princeton,’ ‘Delaware,’ and ‘New Harmony,’ and selections N3487, R18-2, 290, 190, and GDH. The non-American selections 51 and 970 also exhibited high levels of disease tolerance. Most susceptible were American clones 57845, ‘Augustine,’ Crandall, W590, and the American elm seedlings. The most disease-tolerant American elm selections identified in this study are being evaluated further for possible naming and release to the nursery industry.

Preliminary assessments of shoot cold tolerance for American elm bred for enhanced tolerance to Dutch elm disease

2021 ◽  
Author(s):  
Paul Schaberg ◽  
Paula Murakami ◽  
Christopher F. Hansen ◽  
Gary J. Hawley ◽  
Christian O. Marks ◽  
...  
Keyword(s):  
Ambient Temperature ◽  
Cold Tolerance ◽  
Dutch Elm Disease ◽  
Freezing Injury ◽  
Ulmus Americana ◽  
American Elm ◽  
The North ◽  
Cold Tolerant ◽  
Using Data ◽  
Plant Hardiness

Although Dutch elm disease (DED) is the primary threat to American elm (Ulmus americana L.), we hypothesized that shoot freezing injury may also limit tree productivity and survival in the north. We assessed shoot cold tolerance and field winter injury of American elm bred for DED tolerance planted in Lemington, VT. We tested for differences in cold tolerance associated with date, maternal DED tolerance source, paternal sources from plant hardiness zones 5a, 6a and 6b (determined using data from 1996-2005), and the interactions of these. Cold tolerance was greatest in the winter, followed by fall and then spring. For all dates, cold tolerance never differed between maternal DED tolerance sources. However, in mid-winter, paternal sources from zone 5a (coldest zone) were significantly more cold tolerant than sources from zone 6b (warmest zone), and sources from zone 6a were intermediate. Field freezing injury confirmed that shoots were only marginally cold tolerant relative to ambient temperature lows.

scholarly journals Variation in Response of Selected American Elm Clones to Ophiostoma ulmi

1995 ◽  
Vol 13 (3) ◽  
pp. 126-128 ◽  
Author(s):  
A.M. Townsend ◽  
S.E. Bentz ◽  
G.R. Johnson
Keyword(s):  
Dutch Elm Disease ◽  
Main Trunk ◽  
Ulmus Americana ◽  
Disease Symptoms ◽  
Ophiostoma Ulmi ◽  
American Elm ◽  
Causal Fungus ◽  
One Year ◽  
Crown Dieback ◽  
High Degree

Abstract Ramets of nine American elm (Ulmus americana L.) clones or cultivars were planted with ramets of Ulmus ‘Frontier’, Ulmus ‘Prospector’, and American elm seedlings in a randomized block, split-plot design. When they were three years old, the trees were inoculated in the main trunk on either one of two selected dates in May with a spore suspension of Ophiostoma ulmi, the causal fungus for Dutch elm disease (DED). Analyses of variance showed significant variation among clones and between inoculation dates in disease symptoms four weeks and one year after inoculation. Inoculations made on May 18 generally created significantly more symptoms than inoculations made only nine days later. Four-week symptom expression was influenced also by a significant interaction between clonal or seedling group and inoculation date. When data from both inoculation dates were combined, six American elm clones (‘American Liberty’, ‘Princeton’, 680, R18–2, 180, and 3) showed significantly fewer foliar symptoms after four weeks than the American elm seedlings and three other American elm clones. Five of these same six more tolerant American clones averaged significantly less crown dieback after one year than the other American clones or seedlings tested. One of the American elm clones (clone 3) showed a level of disease tolerance equal statistically to ‘Frontier’ and ‘Prospector’, two cultivars which have shown a high degree of tolerance to DED in other studies.

In vitro conservation of American elm (Ulmus americana): potential role of auxin metabolism in sustained plant proliferation

2012 ◽  
Vol 42 (4) ◽  
pp. 686-697 ◽  
Author(s):  
Mukund R. Shukla ◽  
A. Maxwell P. Jones ◽  
J. Alan Sullivan ◽  
Chunzhao Liu ◽  
Susan Gosling ◽  
...  
Keyword(s):  
Dutch Elm Disease ◽  
Multiplication Rate ◽  
Mature Trees ◽  
Endangered Tree ◽  
In Vitro Proliferation ◽  
Ulmus Americana ◽  
Auxin Metabolism ◽  
American Elm

An efficient procedure for the conservation of mature American elm ( Ulmus americana L.) trees that have survived the epidemics of Dutch elm disease and are potential sources of disease resistance is reported. The model utilizes in vitro proliferation of fresh and dormant buds from mature trees for cloning nearly 100 year old American elm trees. The key factors that influenced sustained growth and multiplication included optimization of culture process and auxin metabolism in the source tissue. Blocking the action of endogenous auxins through the addition of antiauxin in the proliferation medium was crucial for high multiplication rate and optimum shoot development. Addition of antiauxin also mitigated the decline in productivity observed with multiple subcultures, which will enable long-term conservation of selected germplasm. The most effective medium for long-term proliferation contained 5.0 µmol/L p-chlorophenoxyisobutyric acid with 2.2 µmol/L benzylaminopurine and 0.29 µmol/L gibberellic acid. Medium with 2.5 µmol/L indole-3-butyric acid was the best for rooting microshoots (89%). Rooted plantlets were readily acclimatized to the greenhouse environment with a 90% survival rate. The strategy developed for American elm will aid in increasing multiplication of resistant clones, facilitate long-term conservation of elite genotypes, and also provide an approach to improve conservation of other endangered tree species.

Ultrastructural cell wall modifications in secondary xylem of American elm surviving the acute stage of Dutch elm disease: vessel members

1981 ◽  
Vol 59 (12) ◽  
pp. 2411-2424 ◽  
Author(s):  
G. B. Ouellette
Keyword(s):  
Vessel Wall ◽  
Coating Layer ◽  
Acute Stage ◽  
Dutch Elm Disease ◽  
Disease Stage ◽  
Ulmus Americana ◽  
Tree Resistance ◽  
Pit Membrane ◽  
Dense Band ◽  
Ultrastructural Characteristics

Modified vessel wall layers and their ultrastructural characteristics in branches of artificially inoculated elm (Ulmus americana L.) trees surviving the acute disease stage and of naturally infected, chronically diseased trees are described. Walls of large early-wood vessels in zones where disease action was prevalent have a strong stain reaction and may be uniformly or locally three to four times thicker than normal.In smaller vessels (some including vessel tracheids), an extra lignified-like, often discontinuous layer may be present. This layer is generally demarcated from the normal by a dense band. Pit membranes and vessel end plates are likewise much thickened through the presence of an opaque material similar to that of the pit membrane. This material differs from that forming the coating layer which like tyloses is generally present inside the thickened or extra vessel wall layer.The possible significance of these observations, particularly in relation to disease development and tree resistance, is discussed.

scholarly journals Rapid Removal of Symptomatic Trees Reduces Dutch Elm Disease Infection Rates

2012 ◽  
Vol 38 (3) ◽  
pp. 99-104
Author(s):  
J. Veilleux ◽  
J. Leferink ◽  
N.J. Holliday
Keyword(s):  
Dutch Elm Disease ◽  
Infection Rates ◽  
Ulmus Americana ◽  
American Elm ◽  
Annual Prevalence ◽  
Urban Study ◽  
Rapid Removal

In the province of Manitoba, Canada, 14 communities were paired on the basis of size and location. From 2004 to 2010 in one member of each pair, rapid removal of American elm (Ulmus americana) trees that displayed symptoms of Dutch elm disease was practiced: newly symptomatic trees were removed within six weeks of symptom detection. The remaining member of each pair continued with autumn or winter removal of symptomatic trees. Treed urban study areas were selected in each community, and in 2008 an inventory of U. americana was taken in these areas. From this inventory and from records of tree removals, estimates of the number of living U. americana and prevalence of Dutch elm disease were made for each year from 2004 to 2010. Following the switch to rapid removal, the annual prevalence of Dutch elm disease in rapid removal communities was 1.5 ± 0.2%, significantly lower than in communities with autumn/winter removal (3.1 ± 0.4%). The study authors estimate that in similar areas the value of the elm resource after 10 years would be almost CAD $600,000/km2 greater if rapid removal rather than autumn/winter removal were practiced. Therefore, under conditions similar to those in these communities, rapid removal should be a component of management programs for Dutch elm disease.

Light and electron microscope studies on cell wall breakdown in American elm xylem tissues infected with Dutch elm disease

1978 ◽  
Vol 56 (21) ◽  
pp. 2666-2693 ◽  
Author(s):  
G. B. Ouellette
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Dutch Elm Disease ◽  
Fibrillar Material ◽  
American Elm ◽  
Cell Wall Disruption ◽  
Extensive Cell ◽  
Cell Wall Breakdown

Seven years (1970–1977) of comparative light and electron microscope studies show that extensive cell wall disruption and breakdown occur consistently in elm xylem tissues infected by Ceratocystis ulmi (Buism.) C. Moreau. These alterations, noticeable even in incipient infection, can be related to the severity of wilting development and occur in association with the presence of an unbound osmiophilic material containing fine fibrillar material, dense particles of approximately 15 nm, and multilamellate structures. Masses of unbound osmiophilic material in host walls and walled fungal cells with which it is sometimes continuous are highly and exclusively labeled following injection of [6-3H]thymidine.The presence of osmiophilic material in host walls and the interrelation between the two was further established by examining stereoscopic pairs of prints taken at various angles with a goniometer. This type of cell wall breakdown seems difficult to relate to other known types of wood rots. Further discussion on the possible nature and origin of the osmiophilic material is presented.

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