Competition among Sclerotinia sclerotiorum genotypes within canola stems

1997 ◽  
Vol 75 (3) ◽  
pp. 462-468 ◽  
Author(s):  
A. D. Maltby ◽  
J. D. Mihail
Keyword(s):  
Population Structure ◽  
Key Words ◽  
Sclerotinia Sclerotiorum ◽  
Competitive Ability ◽  
Greenhouse Experiments ◽  
Genotype Frequencies ◽  
Mycelial Compatibility ◽  
The Mean ◽  
Fungal Reproduction ◽  
Sclerotium Formation

Populations of Sclerotinia sclerotiorum are often composed of multiple genotypes. In examining 35 naturally infected canola plants, 29 supported reproduction (i.e., sclerotium formation) by a single S. sclerotiorum genotype, as defined by the mycelial compatibility test. Only six plants supported reproduction by two genotypes. To test the hypothesis that infrequent multiple genotype infections were due to differences in virulence or competitive ability among isolates, four greenhouse experiments were conducted in which four isolates, representing three genotypes, were used in pairwise coinoculations of canola. There were no differences among the isolates in four virulence parameters. Mean reduction in sclerotial mass produced by a coinoculated isolate was calculated by comparison with the mean sclerotial mass of that isolate in the absence of competition, and used as the measure of competition. In all experiments, at least half of the coinoculation treatments resulted in reduced fungal reproduction for one or both of the coinoculated isolates, providing evidence of competitive differences. Generally, the magnitude of reproduction reduction was the same for each isolate in the pair. However, the magnitude was nonreciprocal when the more competitive isolate was given an advantage of early temporal arrival or spatial placement of inoculum at the lower position on the stem. Competitive differences among S. sclerotiorum isolates affecting reproduction represent one possible mechanism to explain temporal shifts in genotype frequencies. Key words: canola, competition, population structure, Sclerotinia sclerotiorum, virulence.

scholarly journals Mycelial Compatibility Grouping and Aggressiveness of Sclerotinia sclerotiorum

Plant Disease ◽  
2004 ◽  
Vol 88 (4) ◽  
pp. 325-332 ◽  
Author(s):  
L. S. Kull ◽  
W. L. Pedersen ◽  
D. Palmquist ◽  
G. L. Hartman
Keyword(s):  
Population Structure ◽  
Disease Management ◽  
Sclerotinia Sclerotiorum ◽  
Stem Rot ◽  
Management Systems ◽  
Sclerotinia Stem Rot ◽  
Pathogen Population ◽  
Causal Organism ◽  
Soybean Field ◽  
Mycelial Compatibility

Population variability of Sclerotinia sclerotiorum, the causal organism of Sclerotinia stem rot of soybean, was determined by mycelial compatibility grouping (MCG) and isolate aggressiveness comparisons. MCG and aggressiveness of S. sclerotiorum isolates from diverse hosts and geographic locations (Diverse Set, 24 isolates), from a soybean field in Argentina (Argentine Set, 21 isolates), and from soybean fields in DeKalb and Watseka, Illinois (DeKalb Set, 124 isolates, and Watseka Set, 130 isolates) were assessed. Among 299 isolates tested, 42 MCGs were identified, and 61% were represented by single isolates observed at single locations. Within the Diverse Set, 17 MCGs were identified; 1 MCG consisted of six isolates, and 16 MCGs consisted of one isolate each. Nine MCGs were identified within the Argentine field with two MCGs composed of either five or six isolates, two MCGs composed of two isolates, and the remaining composed of one isolate each. Each Illinois field was a mosaic of MCGs, but MCG frequencies differed between the two fields. Common MCGs were identified among the Diverse, DeKalb, and Watseka Sets, but no MCGs within the Argentine Set were observed with other sets. MCG 8 was the most frequently sampled and widely dispersed MCG and occurred at a frequency of 29, 36, and 62% in the Diverse, DeKalb, and Watseka Sets, respectively. Variation in isolate aggressiveness was assessed using a limited-term, plug inoculation technique. Isolate aggressiveness varied (P = 0.001) within the Diverse, Argentine, DeKalb, and Watseka Sets. Within widely dispersed MCGs, isolate aggressiveness varied (P ≤ 0.10); however, within locally observed MCGs detected only in single fields, isolate aggressiveness did not vary. Additionally, individual MCGs within the DeKalb and Watseka Sets differed in isolate aggressiveness. Using six soybean cultivars and six S. sclerotiorum isolates, no cultivar-isolate interaction was detected, but resistant and susceptible cultivars performed similarly when inoculated with either less or highly aggressive isolates. Pathogen population structure and variability in isolate aggressiveness may be important considerations in disease management systems.

scholarly journals High Genetic Diversity, Phenotypic Uniformity, and Evidence of Outcrossing in Sclerotinia Sclerotiorum in the Columbia Basin of Washington State

2004 ◽  
Vol 94 (7) ◽  
pp. 737-742 ◽  
Author(s):  
Z. K. Atallah ◽  
B. Larget ◽  
X. Chen ◽  
D. A. Johnson
Keyword(s):  
Population Structure ◽  
Sclerotinia Sclerotiorum ◽  
Management Strategies ◽  
Stem Rot ◽  
Columbia Basin ◽  
High Genetic Diversity ◽  
Association Analyses ◽  
Haplotypic Diversity ◽  
Mycelial Compatibility

Sclerotinia sclerotiorum, the causal agent of potato stem rot, is prevalent and poorly managed on potatoes in the Columbia Basin of Washington. Because of the ubiquitous nature of the fungus and high crop diversity within the Columbia Basin, understanding the population structure and the potential for outcrossing of the pathogen would be helpful in developing disease management strategies. The population structure of S. sclerotiorum in the Columbia Basin from potato was examined using microsatellite markers and mycelial compatibility. Analysis of molecular variance revealed that 92% of the variability among 167 isolates was found within subpopulations, with limited, yet statistically significant impact of the collection date, but not the year or location of collection. Linkage disequilibrium and index of association analyses noted a potential for outcrossing in two locations, which was substantiated by the discovery of recombinant ascospores in three field-generated apothecia from the 12 apothecia examined. Microsatellite haplotypes were not correlated with mycelial compatibility groups. This high haplotypic diversity did not seem to impact pathologically important phenotypes. Greenhouse inoculations of potato plants exhibited no significant differences in aggressiveness on potato stems. Moreover, in vitro studies of response to fungicides and temperature stimuli yielded no significant differences among studied isolates. These findings illustrate the potential for outcrossing in warm temperate regions of North America, where a diversity of crops are planted simultaneously and in neighboring fields. This study also indicates that the unsatisfactory management of potato stem rot is likely not directly attributable to genetic factors, but to gaps in agricultural practices.

scholarly journals Population Structure and Aggressiveness of Sclerotinia sclerotiorum From Rapeseed (Brassica napus) in Chongqing City

Plant Disease ◽  
2020 ◽  
Vol 104 (4) ◽  
pp. 1201-1206
Author(s):  
Yang Yu ◽  
Junsong Cai ◽  
Linhao Ma ◽  
Zhiqiang Huang ◽  
Yabo Wang ◽  
...  
Keyword(s):  
Population Structure ◽  
Sclerotinia Sclerotiorum ◽  
Plant Pathogens ◽  
Gene Diversity ◽  
Sclerotinia Stem Rot ◽  
Pair Group ◽  
Fungal Plant Pathogens ◽  
Chongqing City ◽  
Mycelial Compatibility ◽  
Rapeseed Production

Sclerotinia sclerotiorum is one of the most devastating fungal plant pathogens of oilseed Brassica and is distributed worldwide. In particular, Sclerotinia stem rot has always been a serious threat to rapeseed production in Chongqing City, China. In this study, simple sequence repeat (SSR) markers and mycelial compatibility groups (MCGs) were used to characterize the population structure of 90 geographic isolates of S. sclerotiorum collected from rapeseed in nine counties of Chongqing. A total of 52 microsatellite haplotypes were identified, and a few haplotypes were found with high frequency. Gene diversity ranged from 0.1570 to 0.4700 in nine populations. A constructed unweighted pair group with arithmetic mean dendrogram based on Nei genetic distance and a STRUCTURE analysis revealed that the genetic composition of the isolates collected in the five counties located in western Chongqing are different from those collected in the two eastern counties, suggesting that breed lines should be cultivated in both the western and eastern regions to effectively evaluate resistance levels. A total of 47 MCGs were identified, and 72% of the MCGs was represented by single isolates. Seven of 13 MCGs that included at least two isolates contained isolates from only one county. SSR haplotypes were not correlated with MCGs. A subset of 34 isolates were inoculated on rapeseed stems, and the aggressiveness showed variation. This research revealed the population genetic structure and aggressiveness of this pathogen in Chongqing, and the results will help to develop disease management and resistance screening strategies.

KNOWLEDGE, ATTITUDE AND PRACTICES OF CARETAKERS AND HEALTH PROFESSIONALS TOWARD TEETHING IN INFANTS

2011 ◽  
pp. 52-59
Author(s):  
Binh Bao Son Bui
Keyword(s):  
Sleep Disturbance ◽  
Key Words ◽  
Breast Feeding ◽  
Health Professionals ◽  
Feeding Problems ◽  
Central Hospital ◽  
Pediatric Department ◽  
Correct Knowledge ◽  
The Mean

Objective and methods: a prospective questionnaire based study on 71 parents (caretakers) of consecutive children treated at the Pediatric Department, Hue Central Hospital and on 47 health professionals at the department was conducted from September until December 2009 to investigate the knowledge, attitude and practices of the caretakers, nurses and postgraduated doctors toward teething in infants. Results: Most responders believed that teething causes fever, irritability, feeding problems, drooling, biting, sleep disturbance, swollen gums, crying, lose of appetite for solids; and fever over 38oC was also believed to be associated with teething. The mean eruption time of the first tooth was from 6 months. Most caretakers had normal attitude to manifestations ascribed to teething (54.9%). The most common management to symptoms attributed to teething included increased breast-feeding, oral paracetamol, increased fluid supplying and physician consulting. Conclusion: Correct knowledge to teething in infants need to be educated for parents (caretakers) and even for health professionals. Key words: knowledge, attitude, practices, teething, infants.

CLINICAL CHARACTERISTICS OF THE CHRONIC DACRYOCYSTITIS AND THE SUCCESS RATE OF EXTERNAL DACRYOCYSTORHINOSTOMY

2015 ◽  
pp. 29-34
Author(s):  
Van Nam Phan ◽  
Ba Kien Tran
Keyword(s):  
Success Rate ◽  
Key Words ◽  
Clinical Characteristics ◽  
Lacrimal Duct ◽  
Interventional Study ◽  
Chronic Dacryocystitis ◽  
External Dacryocystorhinostomy ◽  
The Mean

Purpose: To determine the clinical characteristics of the chronic dacryocystitis and the success rate of external dacryocystorhinostomy. Methods: The retrospective, interventional study without comparing on 27 patients (32 eyes) of chronic dacryocystitis who underwent dacryocystorhinostomy (DCR) from 2010 to 2011. Results were evaluated with standards: epiphora, purelence, lacrimal duct irrigation. Results: Over period of 6 months, 27 patients including 25 (92.59%) female, 2 (7.41%) male. The mean age was 49.8 years (range, 22-79 years). All patients demonstrated epiphera (range, 3 months – 11 years). Dacryocystorhinostomy was performed unilaterally in 81.48%, bilateral 18.52%. Successrate was 90.06% overall. Conclusions: Although techniques in dacryocystorhinostomy of DUPUY-DUTEMPS is old, its result is mainstay of treatment for chronic dacryocystitis in Vietnam. Key words: Dupuy-Dutemps, chronic dacryocystitis

RESULTS OF INTRALESIONAL TRIAMCINOLONE ACETONIDE FOR CHALAZION TREATMENT

2011 ◽  
pp. 100-104
Author(s):  
Thi Thu Nguyen ◽  
Viet Hien Vo ◽  
Thi Em Do
Keyword(s):  
Success Rate ◽  
Key Words ◽  
Triamcinolone Acetonide ◽  
Lower Eyelid ◽  
Upper Eyelid ◽  
Interventional Trial ◽  
The Mean ◽  
First Time

The study use intralesional triamcinolone acetonide injection proceduce for chalazion treatment.1. Objectives: To evaluate results of intralesional triamcinolone acetonide injection for chalazion treatment. 2. Method: This noncomparative prospective interventional trial included 72 chalazions of 61 patients. 3. Results: 61 patients (72 chalazions) with 19 males (31.1%) và 42 females (68.9%), the mean age was 24 ± 9,78 years. 31.1% patients was the first time chalazion and 68.9% patients was more than one times chalazion including 78.6% patients was recurrent at the first position and 21.4% patients occur at new position. 72 chalazions with 16 (22.2%) chalazions was treated before and 56 (77.8%) chalazions wasn’t done that. 72 chalazions with 49 chalazions (68.1%) are local in upper eyelid and 23 chalazions (31.9%) are local in lower eyelid. The mean of chalazion diameter is 6.99 ± 3.03mm. Intralesional triamcinolone acetonide is injected to treat 72 chalazions with 16 (22.2%) chalazions are injected through the route of skin and 56 (77.8%) chalazions are injected through the route of conjunctiva. After 2 weeks follow-up, the success rate was 93.1% and 6.9% failed. 4. Conclusion: intralesional triamcinolone acetonide injection for chalazion treatment is really effective. Key words: chalazion, intralesional triamcinolone acetonide.

scholarly journals Population density of helminths in ducks: effects of host’s age, sex, breed and season

1970 ◽  
Vol 6 (1) ◽  
pp. 45-51 ◽  
Author(s):  
T Farjana ◽  
KR Islam ◽  
MMH Mondal
Keyword(s):  
Population Density ◽  
Key Words ◽  
Parasitic Infection ◽  
Winter Season ◽  
Helminth Parasites ◽  
Domestic Ducks ◽  
The Mean

 A study was conducted to investigate the population density of helminth parasites in domestic ducks (Anas boschas domesticus) in relation to host's age, sex, breed and seasons of the year from March 2002 to May 2003. A total of 300 ducks were collected from different villages of Netrokona and Mymensingh districts of Bangladesh and autopsied to collect the parasites and counted to determine the population density of parasites. Off 300 ducks examined, 290 (96.66%) were infected with 17 species of helminth parasites in which 11 species were trematodes, 4 were cestodes and 2 nematodes. Among the parasites, density of cestodes was the highest (33.15±5.26), followed by trematodes (5.98±1.32); and nematodes (2.95±0.68). Mean density of parasites increased with the increase of age (young: 21.23±1.09, adult: 26.18±2.14 and old: 27.87±2.98) while the mean density of most of the helminth parasites was higher in female ducks (31.35±4.72) than in males (27.52±3.32). Indigenous ducks (33.72±3.61) were infected with the highest load of helminths than Khaki Campbell breed (29.61±4.32) of ducks. Mean density of most trematodes (5.42±0.80) were highest in winter season whereas mean density of all cestodes (48.43±4.85) and nematodes (4.13±1.76) were highest in summer.  The present study suggests that age, sex, breed of ducks and seasons of the year influence the parasitic infection to a greater extend. Key words: Population density, helminths, duck, Bangladesh DOI = 10.3329/bjvm.v6i1.1338 Bangl. J. Vet. Med. (2008). 6 (1): 45-51

scholarly journals Population structure of Chinese southwest wheat germplasms resistant to stripe rust and powdery mildew using the DArT-seq technique

2018 ◽  
Vol 48 (4) ◽  
Author(s):  
Tianqing Chen ◽  
Piyada Alisha Tantasawat ◽  
Wei Wang ◽  
Xu Gao ◽  
Liyi Zhang
Keyword(s):  
Population Structure ◽  
Disease Resistance ◽  
Polymorphic Information Content ◽  
Wheat Breeding ◽  
Wheat Varieties ◽  
Group I ◽  
Population Structure Analysis ◽  
Specific Allele ◽  
The Mean ◽  
Different Origins

ABSTRACT: Understanding genetic variability in existing wheat accessions is critical for collection, conservation and use of wheat germplasms. In this study, 138 Chinese southwest wheat accessions were investigated by genotyping using two resistance gene makers (Pm21 and Yr26) and DArT-seq technique. Finally, about 50% cultivars (lines) amplified the specific allele for the Yr26 gene (Gwm11) and 40.6% for the Pm21 gene (SCAR1265). By DArT-seq analysis, 30,485 markers (6486 SNPs and 23999 DArTs) were obtained with mean polymorphic information content (PIC) value 0.33 and 0.28 for DArT and SNP marker, respectively. The mean Dice genetic similarity coefficient (GS) was 0.72. Two consistent groups of wheat varieties were identified using principal coordinate analysis (PCoA) at the level of both the chromosome 6AS and the whole-genome, respectively. Group I was composed of non-6VS/6AL translocation lines of different origins, while Group II was composed of 6VS/6AL translocation (T6VS/6AL) lines, most of which carried the Yr26 and Pm21 genes and originated from Guizhou. Besides, a model-based population structure analysis revealed extensive admixture and further divided these wheat accessions into six subgroups (SG1, SG2, SG3, SG4, SG5 and SG6), based on their origin, pedigree or disease resistance. This information is useful for wheat breeding in southwestern China and association mapping for disease resistance using these wheat germplasms in future.

scholarly journals Reduced Translocation Is Associated with Tolerance of Common Lambsquarters (Chenopodium album) to Glyphosate

Weed Science ◽  
2013 ◽  
Vol 61 (3) ◽  
pp. 353-360 ◽  
Author(s):  
Melinda K. Yerka ◽  
Andrew T. Wiersma ◽  
R. Bradley Lindenmayer ◽  
Philip Westra ◽  
William G. Johnson ◽  
...  
Keyword(s):  
Competitive Ability ◽  
Chenopodium Album ◽  
Protein Abundance ◽  
Crop Species ◽  
Common Lambsquarters ◽  
Treated Leaf ◽  
The Mean ◽  
Shoot Mass ◽  
Sites Of Action

Common lambsquarters tolerance to glyphosate is problematic because of the species' widespread distribution, competitive ability with many crop species, the widespread use of glyphosate in agriculture, and the weed's potential to develop decreased sensitivity to multiple herbicide sites of action. The mechanism that confers common lambsquarters tolerance to glyphosate is not known. Therefore, we conducted experiments to determine the mechanism of tolerance to glyphosate in an accession of common lambsquarters from Indiana relative to a sensitive accession from Wisconsin. The ED50(the effective dose that reduced shoot mass 50% relative to nontreated plants) value for the tolerant accession (1.6 kg ae ha−1± 0.4 standard error of the mean [SEM]) was eightfold greater than the ED50for the sensitive accession (0.2 kg ae ha−1± 0.2 SEM) 28 d after treatment. The glyphosate target-site (EPSPS) DNA sequence at proline 106, shikimate accumulation as an estimate of EPSPS sensitivity, and EPSPS protein abundance did not differ between accessions. Absorption of14C-glyphosate was slightly greater in the tolerant accession than it was in the sensitive accession at 48 and 72 h after treatment (HAT). However, the tolerant accession translocated a smaller percentage of absorbed14C-glyphosate to the tissue above the treated leaf, which included the shoot apical meristem, at 24, 48, and 72 HAT (P ≤ 0.05, 0.01, and 0.10, respectively). These results suggest an important role of reduced translocation in conferring tolerance of common lambsquarters to glyphosate.

scholarly journals Selection, Load and Inbreeding Depression in a Large Metapopulation

Genetics ◽  
2002 ◽  
Vol 160 (3) ◽  
pp. 1191-1202 ◽  
Author(s):  
Michael C Whitlock
Keyword(s):  
Population Structure ◽  
Inbreeding Depression ◽  
Population Subdivision ◽  
Response To Selection ◽  
Mutation Load ◽  
Deleterious Alleles ◽  
Subdivided Population ◽  
Soft Selection ◽  
Mean Fitness ◽  
The Mean

Abstract The subdivision of a species into local populations causes its response to selection to change, even if selection is uniform across space. Population structure increases the frequency of homozygotes and therefore makes selection on homozygous effects more effective. However, population subdivision can increase the probability of competition among relatives, which may reduce the efficacy of selection. As a result, the response to selection can be either increased or decreased in a subdivided population relative to an undivided one, depending on the dominance coefficient FST and whether selection is hard or soft. Realistic levels of population structure tend to reduce the mean frequency of deleterious alleles. The mutation load tends to be decreased in a subdivided population for recessive alleles, as does the expected inbreeding depression. The magnitude of the effects of population subdivision tends to be greatest in species with hard selection rather than soft selection. Population structure can play an important role in determining the mean fitness of populations at equilibrium between mutation and selection.

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