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 ◽  
...  

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.

2001 ◽  
Vol 19 (2) ◽  
pp. 100-103 ◽  
Author(s):  
A.M. Townsend ◽  
L.W. Douglass

Abstract Rooted stem cuttings of eight American elm (Ulmus americana L.) cultivars or selections, in addition to rooted stem cuttings of two non-American elm cultivars, ‘Prospector’ (U. wilsoniana Schneid.) and ‘Frontier’ (U. carpinifolia Gleditsch x U. parvifolia Jacq.), all planted in a randomized block, split-plot design, were inoculated on either one of two dates in May 1992 with a mixed spore suspension of Ophiostoma ulmi (Buisman) C. Nannf. and Ophiostoma novo-ulmi Brasier, the causal fungi for Dutch elm disease (DED). Crown dieback and survival were recorded once yearly for 7 years following inoculations, and height growth was measured after the sixth growing season. Analyses of variance and regression showed significant differences in disease severity among all clones tested. Among the American elms, crown dieback and mortality over time were least for ‘Valley Forge,’ ‘Princeton,’ and ‘New Harmony; ’ intermediate for ‘Delaware’ and selection R18-2; and greatest for selections 57845 and 11 and the cultivar American Liberty. Dieback and survival of ‘Prospector’ and ‘Frontier,’ the non-American elms, were comparable to that of the more disease-tolerant American elm clones. Height growth on surviving American elms for six years after inoculation was greatest for ‘Valley Forge’ and ‘Princeton’ and least for 57845, 11, and ‘American Liberty.’ Results demonstrate the ability of certain American elm cultivars and selections to respond and then recover from heavy doses of the two fungi which cause DED.


Author(s):  
B. L. Redmond ◽  
Christopher F. Bob

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.


1992 ◽  
Vol 176 (2) ◽  
pp. 351-361 ◽  
Author(s):  
H Kodama ◽  
M Nose ◽  
Y Yamaguchi ◽  
J Tsunoda ◽  
T Suda ◽  
...  

The preadipose cell line, PA6, can support long-term hemopoiesis. Frequency of the hemopoietic stem cells capable of sustaining hemopoiesis in cocultures of bone marrow cells and PA6 cells for 6 wk was 1/5.3 x 10(4) bone marrow cells. In the group of dishes into which bone marrow cells had been inoculated at 2.5 x 10(4) cells/dish, 3 of 19 dishes (16%) contained stem cells capable of reconstituting erythropoiesis of WBB6F1-W/Wv mice, indicating that PA6 cells can support the proliferation of primitive hemopoietic stem cells. When the cocultures were treated with an antagonistic anti-c-kit monoclonal antibody, ACK2, only a small number of day 12 spleen colony-forming units survived; and hemopoiesis was severely reduced. However, when the cocultures were continued with antibody-free medium, hemopoiesis dramatically recovered. To examine the proliferative properties of the ACK2-resistant stem cells, we developed a colony assay system by modifying our coculture system. Sequential observations of the development of individual colonies and their disappearance demonstrated that the stem cells having higher proliferative capacity preferentially survive the ACK2 treatment. Furthermore, cells of subclones of the PA6 clone that were incapable of supporting long-term hemopoiesis expressed mRNA for the c-kit ligand. These results suggest that a mechanism(s) other than that involving c-kit receptor and its ligand plays an important role in the survival and proliferation of primitive hemopoietic stem cells.


HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 584f-584 ◽  
Author(s):  
Z. M. Cheng ◽  
N. O. Shi ◽  
L. Tokach ◽  
B. K. Gaschk

Shoot regeneration was obtained from leaf tissues of American (Ulmus americana) and Siberian elm (U. pumila) seedlings germinated in vitro and in greenhouse. Murashige and Skoog (MS, 1962) media supplemented with 4 levels of BA (0, 5, 10, 15, 20 μM) and 3 levels of IBA (0, 2.5, 5.0 μM) were tested in a factorial design to find an optimal hormonal combination for shoot regeneration. Shoot regeneration was obtained from both species within 3-4 weeks in a wide range of media. The highest regeneration rate (50%) of American elm was in the medium containing 10 μM BA and 2.5 μM IBA. Incubation under the light was essential for a higher rate of regeneration. Gelrite was found as a better solidifying agent than agar. The progress is under way to achieve transgenic elms by combining this regeneration system with Agrobacterium-mediated transformation.


HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 693b-693
Author(s):  
Xiaoling Yu ◽  
Barbara M. Reed

Multiplication and elongation of shoot cultures established from mature trees of hazelnut cvs. Nonpareil and Tonda Gentile Romana were affected by changes in basal medium, carbon source and concentration, cytokinin and agar concentration. Explants on DKW medium produced significantly more shoots than those on Anderson medium or modified woody plant medium for chestnut. Explants on DKW medium with 3% glucose or fructose gave more and longer shoots than those with the other carbon sources. Cytokinins 6 benzylaminopurine (BA) and zeatin were more effective in producing shoots than kinetin and 2iP. On BA supplemented medium, the best multiplication rate was obtained with 1.5 - 2.0 mg/l. Explants grown on 0.4% agar produced more shoots than those on 0.6%, however, prolonged culture on 0.4% agar caused vitrification of lower parts of the plants. Shoot multiplication rates of these two cultivars were similar, but `Nonpareil' produced longer shoots than `Tonda Gentile Romana'.


2005 ◽  
Vol 23 (1) ◽  
pp. 21-24 ◽  
Author(s):  
A. M. Townsend ◽  
S. E. Bentz ◽  
L. W. Douglass

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.


2021 ◽  
Author(s):  
Jose Javier Regalado González ◽  
Manuel López Granero ◽  
Carlos Lopez Encina

Abstract We present the data on proliferation corresponding to 10 years of continuous incubation in vitro of papaya shoots, and propose a reliable method for long-term micropropagation for papaya, using two types of explants: Microshoots from somatic embryos, and from axillary buds of papaya. Three different media were assayed. The proliferation medium (PPRM) allowed to maintain papaya shoots under continuous proliferation during 20 years, maintaining a consistent behaviour. Most of the shoots developed in PPRM rooted during the incubation, and after acclimated easily, maintaining the morphological characteristics of the parental plants, flowering and setting fruits normally. The PPRM medium consist in MS medium supplemented with NAA (0.1 mg l-1), BA (0.5 mg l-1), GA3 (0.5 mg l-1) and Adenine sulphate (40 mg l-1). The average multiplication rate was higher than 20 shoots per explant along the long-term assay. The elongation medium (PELM), was designed to recover shoots with a poor growth, and allowed the development of high quality shoots ready for rooting, and consist in a MS basal medium supplemented with NAA (0.1 mg l-1), Kin (0.5 mg l-1) and GA3 (1 mg l-1). The rooting medium (PROM) was designed to induce high quality roots from non-rooted shoots and consist in a half strength MS medium plus IBA (1mg l-1). On PROM, agar can be exchanged for expanded vermiculite. Acclimation took place inside an acclimatization tunnel under progressive hydric stress. After 4 weeks, the plant recovery rate was 90% for plants maintained under continuous proliferation during ten years.


Author(s):  
Paul Schaberg ◽  
Paula Murakami ◽  
Christopher F. Hansen ◽  
Gary J. Hawley ◽  
Christian O. Marks ◽  
...  

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.


Blood ◽  
1969 ◽  
Vol 33 (2) ◽  
pp. 292-299 ◽  
Author(s):  
PHILIP R. GLADE ◽  
YASHAR HIRSHAUT ◽  
DANIEL P. STITES ◽  
LAWRENCE N. CHESSIN

Abstract The persistence of circulating leukocytes with potential for long-term in vitro proliferation was investigated in patients with heterophile-positive infectious mononucleosis. The ability to isolate long-term suspension cultures from peripheral blood with selective technics was a transient phenomenon for each patient studied, disappearing with a return of clinical and laboratory parameters toward the normal state. There was no close correlation between the ability to isolate cell lines and clinical, morphologic, biosynthetic or serologic manifestations of disease.


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