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ABSTRACT: Flowering dogwood (Cornus florida L.) populations recently have experienced severe declines caused by dogwood anthracnose. Mortality has ranged from 48 to 98%, raising the concern that genetic diversity has been reduced significantly. Microsatellite data were used to evaluate the level and distribution of genetic variation throughout much of the native range of the tree. Genetic variation in areas affected by anthracnose was as high as or higher than areas without die-offs. We found evidence of four widespread, spatially contiguous genetic clusters. However, there was little relationship between geographic distance and genetic difference. These observations suggest that high dispersal rates and large effective population sizes have so far prevented rapid loss of genetic diversity. The effects of anthracnose on demography and community structure are likely to be far more consequential than short-term genetic effects.
Genetica 10/2010; 138(9-10):1047-57. · 2.15 Impact Factor
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D Aurelle,
A J Baker,
L Bottin,
C Brouat,
A Caccone,
A Chaix,
P Dhakal,
Y Ding,
J M Duplantier,
W Fiedler, [......],
Y Tian,
J Tomiuk, R N Trigiano,
M C Ungerer,
A Van Wormhoudt,
P A Wadl,
D-Q Wang,
T Weis-Dootz,
Q Xia,
Q-Y Yuan
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ABSTRACT: This article documents the addition of 228 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Anser cygnoides, Apodemus flavicollis, Athene noctua, Cercis canadensis, Glis glis, Gubernatrix cristata, Haliotis tuberculata, Helianthus maximiliani, Laricobius nigrinus, Laricobius rubidus, Neoheligmonella granjoni, Nephrops norvegicus, Oenanthe javanica, Paramuricea clavata, Pyrrhura orcesi and Samanea saman. These loci were cross-tested on the following species: Apodemus sylvaticus, Laricobius laticollis and Laricobius osakensis (a proposed new species currently being described).
Molecular Ecology Resources 07/2010; 10(4):751-754. · 3.06 Impact Factor
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ABSTRACT: Understanding the relative contribution of the different resistance components is necessary to develop selection schemes and accelerate resistant-cultivar development. This study was conducted to investigate spore germination, infection-structure formation, and fungal development of Erysiphe pulchra, the causal agent of powdery mildew, on leaf disks of six cultivars or lines of flowering dogwood (Cornus florida) with different levels of resistance. The cultivars and lines tested were grouped into the following three resistance categories: highly susceptible (‘Cherokee Daybreak’ and MW 94-60), moderately susceptible (‘Cherokee Princess’ and MW 95-25), and resistant (‘Cherokee Brave’ and ‘Karen’s Appalachian Blush’). Percentages of spore germination and secondary-appressoria formation were not significantly different among the cultivars and lines. Significantly less percent germinated conidia with branched hyphae were observed on resistant cultivars than on the moderately susceptible cultivar or line, which was less than on the highly susceptible cultivar or line. Infection efficiencies were significantly different among cultivars and lines in the three resistance categories, except that there were no differences between ‘Cherokee Princess’ and the resistant cultivars. Resistant cultivars supported shorter latent periods than moderately and highly susceptible cultivars or lines, but no differences in latent period were detected between the later two resistance categories. The recently released ‘Karen’s Appalachian Blush’ expressed higher levels of resistance to powdery mildew than did ‘Cherokee Brave’, as indicated by the longer latent period and reduced relative sporulation of the pathogen.
Canadian Journal of Plant Pathology 03/2010; March 2006(Vol. 28):71-76. · 0.88 Impact Factor
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D Aurelle,
A J Baker,
L Bottin,
C Brouat,
A Caccone,
A Chaix,
P Dhakal,
Y Ding,
J M Duplantier,
W Fiedler, [......],
R Taubert,
Y Tian,
J Tomiuk, R N Trigiano,
M C Ungerer,
A V An Wormhoudt,
P A Wadl,
D.-Q Wang,
T Weis-Dootz,
Q Xia
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L G Abercrombie,
C M Anderson,
B G Baldwin,
I C Bang,
R Beldade,
G Bernardi,
A Boubou,
A Branca,
F Bretagnolle,
M W Bruford, [......],
L Wang,
X Wang,
K Watanabe,
J M Waterman,
W W Weisser,
D A Westcott,
K R Wiesner,
X F Xu,
S Yaegashi,
J S Yuan
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ABSTRACT: This article documents the addition of 283 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Agalinis acuta; Ambrosia artemisiifolia; Berula erecta; Casuarius casuarius; Cercospora zeae-maydis; Chorthippus parallelus; Conyza canadensis; Cotesia sesamiae; Epinephelus acanthistius; Ficedula hypoleuca; Grindelia hirsutula; Guadua angustifolia; Leucadendron rubrum; Maritrema novaezealandensis; Meretrix meretrix; Nilaparvata lugens; Oxyeleotris marmoratus; Phoxinus neogaeus; Pristomyrmex punctatus; Pseudobagrus brevicorpus; Seiridium cardinale; Stenopsyche marmorata; Tetranychus evansi and Xerus inauris. These loci were cross-tested on the following species: Agalinis decemloba; Agalinis tenella; Agalinis obtusifolia; Agalinis setacea; Agalinis skinneriana; Cercospora zeina; Cercospora kikuchii; Cercospora sorghi; Mycosphaerella graminicola; Setosphaeria turcica; Magnaporthe oryzae; Cotesia flavipes; Cotesia marginiventris; Grindelia Xpaludosa; Grindelia chiloensis; Grindelia fastigiata; Grindelia lanceolata; Grindelia squarrosa; Leucadendron coniferum; Leucadendron salicifolium; Leucadendron tinctum; Leucadendron meridianum; Laodelphax striatellus; Sogatella furcifera; Phoxinus eos; Phoxinus rigidus; Phoxinus brevispinosus; Phoxinus bicolor; Tetranychus urticae; Tetranychus turkestani; Tetranychus ludeni; Tetranychus neocaledonicus; Tetranychus amicus; Amphitetranychus viennensis; Eotetranychus rubiphilus; Eotetranychus tiliarium; Oligonychus perseae; Panonychus citri; Bryobia rubrioculus; Schizonobia bundi; Petrobia harti; Xerus princeps; Spermophilus tridecemlineatus and Sciurus carolinensis.
Molecular Ecology Resources 09/2009; 9(5):1375-1379. · 3.06 Impact Factor
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ABSTRACT: Microsatellite discovery from genomic libraries is tedious because of the low number of clones that contain inserts and costly because of screening methodologies. A new procedure for screening clones for microsatellite DNA is described herein. Instead of colony hybridization, a polymerase chain reaction (PCR) with two vector standard primers and one synthesized repeat primer was used to directly screen colonies. PCR of colonies that produced a strong smear in gels contained the desired motif, whereas a single strong band indicated the lack of the desired motif. This simple screening method is a cost-effective way to identify microsatellite-containing colonies.
Molecular Ecology Notes 06/2007; 7(4):558 - 561. · 2.38 Impact Factor
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ABSTRACT: The anthracnose epidemic caused by exotic filamentous fungi of the genus Discula threatens the future of the prized flowering (Cornus florida L.) and Pacific (C. nuttalli Aud.) dogwoods in North America. A cross-section of fungi that cause anthracnose in broadleaf temperate trees was characterized using DNA amplification fingerprinting, sequence and secondary structure analysis of the internal transcribed spacers (ITS) of nuclear ribosomal DNA (rDNA), and compatibility of hyphal anastomosis. ITS-inferred phylogenies rejected the null hypothesis of only one fungal lineage, by defining four monophyletic and well differentiated groups, corresponding to Discula sp., D. quercina, D. umbrinella and D. destructiva, with the last two species sharing a common and recent ancestor. In turn, they showed that the dogwood pathogen, D. destructiva, did not evolve directly from an indigenous population related to Discula sp. In this study, rDNA spacers that are generally considered important for protein synthesis but are selectively neutral, appeared functionally constrained and subject to selective sequence diversification. Results confirmed the high variability of D. umbrinella and the remarkable homogeneity and exotic nature of D. destructiva at the genetic level, clarified the taxonomy and phylogeny of Discula, and provided clues as to the origin and diversification of dogwood anthracnose-causing fungi.
Current Genetics 08/2001; 39(5-6):346-54. · 2.56 Impact Factor
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ABSTRACT: DNA amplification fingerprinting (DAF) with arbitrary oligonucleotide primers was used to study genetic relationships between
cultivars of flowering dogwood (Cornus florida L.), evaluate extent of plant hybridization, and generate markers in pseudo-testcross
mapping at the intraspecific level. Modified Taguchi optimization methods defined a robust DAF system based on high annealing
temperature (48–52 °C) and primer concentration (typically 8 μM) that was used to study genetic diversity of representative
dogwood cultivars and hybrids. Phenetic analysis using cluster and numerical methods showed that: (1) cultivars were relatively
conserved at the genetic level; (2) their hybridization could be identified in the F1 progeny in the absence of phenotypic
or physiological markers; (3) several cultivars grouped according to their recorded ancestry; and (4) dogwood anthracnose-resistant
lines originally selected in Catoctin Mountain Park (Maryland) grouped separately from those of southern origin. The DAF protocol
was also tested in pseudo-testcross mapping of dogwood at the intraspecific level. A preliminary screening of parents ‘Pink
Sachet’ and ‘Fragrant Cloud’ and 7 F1 segregants with 22 octamer primers produced 703 amplified loci, 30 and 39 of which were
male and female markers segregating at 1:1 ratios with 98.6% confidence levels in pseudo-testcross configuration. Overall
results show that DAF generated markers very efficiently (3 per primer) despite the close relatedness of parental dogwood
cultivars. This study constitutes the basis for a future genetic linkage mapping and marker-assisted selection (MAS) effort
initially targeted to control important fungal diseases in dogwood.
Euphytica 04/1999; 106(3):209-222. · 1.55 Impact Factor
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Methods in molecular biology (Clifton, N.J.) 02/1997; 67:111-27.
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ABSTRACT: Isolates of Discula destructiva Redlin and an undescribed species of Discula, the filamentous fungi that cause anthracnose of flowering (Cornus florida L.) and Pacific (Cornus nuttalli Aud.) dogwoods, were analyzed for genetic variation by nucleic acid scanning with arbitrary mini-hairpin oligonucleotide primers. While the fungal population was highly homogeneous throughout the disease range in eastern and western North America, the generation of arbitrary signatures from amplification profiles (ASAP) distinguished isolates from the northeast, middle and southern Appalachian mountain range, and western United States and Canada. ASAP involves a dual-step arbitrary primer-based amplification procedure that generates a large number of informative allelic characters by amplification of monomorphic DNA fingerprints. ASAP analyses showed a fine fungal population structure consistent with the recent and separate introduction of the pathogen on the west and east coasts of North America.
FEMS Microbiology Letters 01/1997; 145(3):377-83. · 2.04 Impact Factor
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ABSTRACT: The relationship of five species of Petunia and ten cultivars of the cultivated petunia, Petunia x hybrida, were investigated using DNA-amplification fingerprinting (DAF). Reproducible banding profiles were obtained from P. parodii and P. axillaris DNA from different seed sources. In contrast, other petunias such as P. inflata, P. violacea and P. integrifolia produced variable fingerprints when different plants were examined. However, representative profiles of the variable Petunia taxa were obtained by bulking the leaf tissue from ten different individual plants. Each of ten octamer primers revealed polymorphic loci between taxa. Among a total of 201 bands produced, 146 (73%) loci were polymorphic and distinguished all species and cultivars. Phenetic and cluster analysis using DAF markers separated P. axillaris from P. parodii and distinguished between the violet-flowered species, P. inflata, P. violacea, and P. integrifolia. P. parodii grouped together with the monophyletic set of the ten cultivars of P. x hybrida examined, indicating that it had made a major contribution to the development of these cultivars. Cultivars were distributed within the dendograms by flower color. The results demonstrated the utility of DAF in establishing relationships among closely related species and cultivars of Petunia.
Theoretical and Applied Genetics 04/1996; 92(8):1009-1016. · 3.30 Impact Factor
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ABSTRACT: Bisected leaves were cultured on semi-solid Murashige & Skoog medium amended with 13.5 M 2,4-D and 4.5 M BA for 7–14 days, transferred to 0.5% activated charcoal medium (without growth regulators) for three days, then transferred to MS basal medium. Control explants remained on initiation medium for comparison to transferred explants. Twenty-eight days after initiation of cultures, explants exposed to 11–14 days on induction medium yielded the largest number and most developmentally advanced embryos. Mature, white somatic embryos from transferred explants were visible after 35 days. Conversely, somatic embryos on control explants were not morphologically mature until 2–4 months. Mature embryos from transferred explants germinated without a resting stage, whereas embryos from control explants appeared quiescent. Histological examination confirmed embryo anatomy, however embryos, regardless of treatment, had abnormal cotyledons and regenerated plants had multiple stems.
Plant Cell Tissue and Organ Culture 01/1994; 36(2):249-253. · 3.09 Impact Factor
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ABSTRACT: Agar is a commonly used gelling agent and a raw material used in other gelling agents. The effects of five gelling agents and potato dextrose agar on urediniospore germination, and changes in percent urediniospore germination and germ-tube elongation in Puccinia hemerocallidis over time were investigated in vitro. Percent urediniospore germination differed significantly between the tested gelling agents. Urediniospores germinated well on Gelrite, agarose, Phytagar, and Oxoid No. 3 agar in decreasing order, and percent urediniospore germination was negatively correlated with the concentration of gelling agent. Urediniospores germinated poorly on the substrates containing more than 0.5% Bacto Agar. The concentration of Bacto Agar that caused 50% inhibition of urediniospore germination was 18.2 µg/mL in 1% agarose substrate. However, there were no significant differences in germ-tube elongation between the concentrations of Bacto Agar water extract tested. Unidentified inhibitory compounds from Bacto Agar water extract were adsorbed on a C18 column and the effluent water did not affect spore germination. However, the methanol-eluted solution from the C18 column completely inhibited urediniospore germination when the solution was evaporated and reconstituted with water. Changes in percent urediniospore germination and germ-tube length on 1% agarose water substrate over time fitted well with negative exponential models. The time to the half-asymptote of percent urediniospore germination and germ-tube length was 1.4 and 6.0 h, respectively, and the time to 95% of the asymptote was 6.1 and 30.9 h for spore germination and germ-tube elongation, respectively.
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ABSTRACT: Sclerotinia homoeocarpa is the causal agent of dollar spot disease that reduces the uniformity and aesthetic value of golf putting greens. Fungicide-resistant isolates of S. homoeocarpa were collected from putting greens at 10 locations across Tennessee and northern Mississippi. Genetic diversity among the 60 isolates was investigated using vegetative compatibility, conserved gene sequences, and amplified fragment length polymorphism (AFLP). Six tester strains were paired with Tennessee and northern Mississippi isolates on potato dextrose agar. Some of the 60 isolates were delineated into vegetative compatibility groups, but fungicide resistance could not be associated with a particular vegetative compatibility group. Genetic similarities of isolates at the vegetative compatibility level could be attributed to founder effects. Sequencing the regions of CAD, EF1-α, β-tubulin, and internal transcribed spacers revealed 100% homology among isolates. Capillary gel electrophoresis and analysis of AFLP fragments indicated 86 to 100% similarity between the isolates. Vegetative compatibility and molecular data indicate that the populations of the pathogen are clonal. Isolates did not cluster according to fungicide resistance during unweighted pair group with arithmetic means analysis, but did appear to cluster according to vegetative compatibility group and location. Although associations could not be made between molecular markers and fungicide resistance, links between vegetative compatibility and AFLP markers may provide a foundation from which other studies could be performed.
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ABSTRACT: Microsatellite discovery from genomic libraries is tedious because of the low number of clones that contain inserts and costly because of screening methodologies. A new procedure for screening clones for microsatellite DNA is described herein. Instead of colony hybridization, a polymerase chain reaction (PCR) with two vector standard primers and one synthesized repeat primer was used to directly screen colonies. PCR of colonies that produced a strong smear in gels contained the desired motif, whereas a single strong band indicated the lack of the desired motif. This simple screening method is a cost-effective way to identify microsatellite-containing colonies.
