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 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 Effect of some fungicides against the growth inhibition of Sclerotinia sclerotiorum mycelial compatibility groups

2015 ◽  
Vol 55 (4) ◽  
pp. 354-361 ◽  
Author(s):  
Alireza Dalili ◽  
Saeed Bakhtiari ◽  
Hossein Barari ◽  
Majid Aldaghi
Keyword(s):  
Growth Inhibition ◽  
Sclerotinia Sclerotiorum ◽  
Integrated Management ◽  
In Vitro Tests ◽  
Sclerotinia Stem Rot ◽  
Mazandaran Province ◽  
Brassica Napus L ◽  
Northern Iran ◽  
Mycelial Compatibility

Abstract Sclerotinia sclerotiorum (Lib.) de Bary, the causal agent of Sclerotinia stem rot, is one of the most important pathogens of Brassica napus L. in northern Iran. In this study, 13 mycelial compatibility groups (MCGs) of the fungus were identified among 31 isolates sampled from four regions of Mazandaran province, Iran. Effective fungicides are useful in the integrated management of the disease. So, the effect of tebuconazole, propiconazole, cyproconazole, and Rovral-TS at five doses (0.0001, 0.001, 0.01, 0.1, and 1 ppm) was studied on the growth inhibition of S. sclerotiorum as in vitro tests. Maximum inhibition (100%) of S. sclerotiorum mycelial growth was obtained by the highest dose (1 ppm) of all tested fungicides, as well as by the doses of 0.1 and 0.01 ppm of propiconazole, cyproconazole, and tebuconazole. In this investigation, the reaction of S. sclerotiorum isolates belonging to different MCGs was evaluated against tebuconazole, propiconazole, cyproconazole, and Rovral-TS at their EC50 ranges. The results revealed that there was high variation of S. sclerotiorum MCGs against different fungicides. The inhibition percentage varied between 4.29% and 71.72%.

scholarly journals Effects of the Novel Fungicide Benzothiostrobin on Sclerotinia sclerotiorum in the Laboratory and on Sclerotinia Stem Rot in Rape Fields

Plant Disease ◽  
2015 ◽  
Vol 99 (7) ◽  
pp. 969-975 ◽  
Author(s):  
Congying Xu ◽  
Xiaoyu Liang ◽  
Yiping Hou ◽  
Mingguo Zhou
Keyword(s):  
Sclerotinia Sclerotiorum ◽  
Pathogenic Fungus ◽  
Field Trials ◽  
Stem Rot ◽  
Cross Resistance ◽  
Synergistic Activity ◽  
The Novel ◽  
Sclerotinia Stem Rot ◽  
Sclerotial Germination

We determined the effects and efficacy of benzothiostrobin, a new strobilurin-derived fungicide, against the plant-pathogenic fungus Sclerotinia sclerotiorum (the causal agent of Sclerotinia stem rot). Mycelial growth and sclerotial germination in vitro were strongly inhibited by benzothiostrobin in the presence of salicylhydroxamic acid. On detached rapeseed leaves, benzothiostrobin at 40 μg/ml reduced lesion development by 87%. No cross-resistance was detected between benzothiostrobin and carbendazim, iprodione, fludioxonil, or boscalid. A formulated mixture of benzothiostrobin and fluazinam at 1:1 had synergistic activity against S. sclerotiorum in vitro. In field trials, benzothiostrobin alone or formulated with fluazinam at 1:1 (150 g a.i. ha−1) was significantly (P < 0.05) superior to iprodione in controlling Sclerotinia stem rot of rapeseed. These results suggest that benzothiostrobin has substantial potential for the control of Sclerotinia stem rot.

scholarly journals Genetic Diversity and Recombination in the Plant Pathogen Sclerotinia sclerotiorum Detected in Sri Lanka

Pathogens ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 306
Author(s):  
Thirega Mahalingam ◽  
Weidong Chen ◽  
Chandima Shashikala Rajapakse ◽  
Kandangamuwa Pathirannahalage Somachandra ◽  
Renuka Nilmini Attanayake
Keyword(s):  
Genetic Diversity ◽  
Genetic Structure ◽  
Sri Lanka ◽  
Sclerotinia Sclerotiorum ◽  
Genetic Recombination ◽  
Multiple Infections ◽  
Tropical Country ◽  
High Genetic Diversity ◽  
Principal Coordinates ◽  
Mycelial Compatibility

Sclerotinia sclerotiorum is an important fungal pathogen on many economically important crops including cabbage worldwide. Even though population structure and genetic diversity of S. sclerotiorum is well studied in temperate climatic conditions, only a few studies have been conducted in tropical countries. It is also not clear whether the populations are clonal or recombining in the tropics. In filling this information gap, 47 isolates of S. sclerotiorum were collected from commercial cabbage (Brassica oleracea L.) fields in Nuwara Eliya district of Sri Lanka, where the disease has been previously reported. All the isolates were subjected to genetic diversity study using mycelial compatibility grouping and microsatellite markers. Fourteen mycelial compatibility groups (MCGs) and 23 multilocus haplotypes (MLHs) were recorded. Mean expected heterozygosity of the population was 0.56. MLHs were weakly correlated with MCGs. Population genetic structure analysis and principal coordinates identified three genetic clusters. Genetic recombination was inferred within each genetic cluster when isolates were subjected to clone correction. There was evidence of multiple infections on single plant as detected by the presence of more than one MCG on each cabbage plant. However, multiple infections did not increase the disease severity in detached leaf assay. We found high genetic diversity and recombination of S. sclerotiorum population in a tropical country, Sri Lanka. Importance of detecting genetic structure when inferring recombination was also highlighted.

scholarly journals Baseline Sensitivity and Control Efficacy of Various Group of Fungicides against Sclerotinia sclerotiorum in Oilseed Rape Cultivation

Agronomy ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1758
Author(s):  
Nazanin Zamani-Noor
Keyword(s):  
Oilseed Rape ◽  
Sclerotinia Sclerotiorum ◽  
Fungicidal Activity ◽  
Management Strategies ◽  
Sclerotinia Stem Rot ◽  
Baseline Sensitivity ◽  
Cultural Management ◽  
Significant Yield ◽  
And Control

Sclerotinia stem rot (SSR), caused by Sclerotinia sclerotiorum, is a devastating disease of oilseed rape that may cause significant yield losses if not controlled by cultural management strategies and fungicide applications. Studies were conducted to evaluate the efficacy of different group of fungicides as well as a biopesticide, including azoxystrobin, boscalid, fludioxonil, prothioconazole, tebuconazole, azoxystrobin/tebuconazole, boscalid/pyraclostrobin, prothioconazole/fluopyram and Bacillus amyloliquefaciens, on baseline sensitivity of S. sclerotiorum isolates under in-vitro conditions as well as control of SSR in the field. Artificial inoculation and mist irrigation prompt to reproducible SSR infection in oilseed rape cultivation. All compounds significantly reduced 36.7% to 86.9% SSR severity and increased 55.2% to 98.7% yield, 1.5% to 7.0% thousand grain-weight, 1.5% to 5.9% oil and 0.1% to 1.3% protein content. Fludioxonil, boscalid/pyraclostrobin and fluopyram/prothioconazole achieved strongest fungicidal activity against SSR. The biopesticide provided 36% of disease control. Under in vitro conditions, B. amyloliquefaciens not only strongly inhibited mycelial growth but also the formation of sclerotia in all concentrations. Boscalid and fludioxonil exhibited the highest level of fungicidal activity against S. sclerotiorum, with mean EC50 values of 1.23 and 1.60 μg a.s. mL−1. The highest variability of EC50 values between isolates was observed towards prothioconazole and azoxystrobin.

scholarly journals In vitro Biofumigation of Brassica Tissues Against Potato Stem Rot Caused by Sclerotinia sclerotiorum

2012 ◽  
Vol 28 (2) ◽  
pp. 185-190 ◽  
Author(s):  
Mohammad Reza Ojaghian ◽  
Heng Jiang ◽  
Guan-Lin Xie ◽  
Zhou-Qi Cui ◽  
Jingze Zhang ◽  
...  
Keyword(s):  
Sclerotinia Sclerotiorum ◽  
Stem Rot

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.

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