scholarly journals Efficacy of Variable Tetraconazole Rates Against Cercospora beticola Isolates with Differing In Vitro Sensitivities to DMI Fungicides

Plant Disease ◽  
2012 ◽  
Vol 96 (12) ◽  
pp. 1749-1756 ◽  
Author(s):  
Melvin D. Bolton ◽  
Viviana Rivera-Varas ◽  
Luis E. del Río Mendoza ◽  
Mohamed F. R. Khan ◽  
Gary A. Secor
Keyword(s):  
Sugar Beet ◽  
Disease Severity ◽  
Cercospora Beticola ◽  
In Planta ◽  
Sensitivity Testing ◽  
In Vitro Sensitivity ◽  
Wide Range ◽  
Fungicide Efficacy ◽  
Dmi Fungicides

Cercospora leaf spot (CLS) of sugar beet is caused by the fungus Cercospora beticola. CLS management practices include the application of the sterol demethylation inhibitor (DMI) fungicides tetraconazole, difenoconazole, and prothioconazole. Evaluating resistance to DMIs is a major focus for CLS fungicide resistance management. Isolates were collected in 1997 and 1998 (baseline sensitivity to tetraconazole, prothioconazole, or difenoconazole) and 2007 through 2010 from the major sugar-beet-growing regions of Minnesota and North Dakota and assessed for in vitro sensitivity to two or three DMI fungicides. Most (47%) isolates collected in 1997–98 exhibited 50% effective concentration (EC50) values for tetraconazole of <0.01 μg ml–1, whereas no isolates could be found in this EC50 range in 2010. Since 2007, annual median and mean tetraconazole EC50 values have generally been increasing, and the frequency of isolates with EC50 values >0.11 μg ml–1 increased from 2008 to 2010. In contrast, the frequency of isolates with EC50 values for prothioconazole of >1.0 μg ml–1 has been decreasing since 2007. Annual median difenoconazole EC50 values appears to be stable, although annual mean EC50 values generally have been increasing for this fungicide. Although EC50 values are important for gauging fungicide sensitivity trends, a rigorous comparison of the relationship between in vitro EC50 values and loss of fungicide efficacy in planta has not been conducted for C. beticola. To explore this, 12 isolates exhibiting a wide range of tetraconazole EC50 values were inoculated to sugar beet but no tetraconazole was applied. No relationship was found between isolate EC50 value and disease severity. To assess whether EC50 values are related to fungicide efficacy in planta, sugar beet plants were sprayed with various dilutions of Eminent, the commercial formulation of tetraconazole, and subsequently inoculated with isolates that exhibited very low, medium, or high tetraconazole EC50 values. The high EC50 isolate caused significantly more disease than isolates with medium or very low EC50 values at the field application rate and most reduced rates. Because in vitro sensitivity testing is typically carried out with the active ingredient of the commercial fungicide, we investigated whether loss of disease control was the same for tetraconazole as for the commercial product Eminent. The high EC50 isolate caused more disease on plants treated with tetraconazole than Eminent but disease severity was not different between plants inoculated with the very low EC50 isolate.

scholarly journals Rapid Detection of Cercospora beticola in Sugar Beet and Mutations Associated with Fungicide Resistance Using LAMP or Probe-Based qPCR

Plant Disease ◽  
2020 ◽  
Vol 104 (6) ◽  
pp. 1654-1661 ◽  
Author(s):  
Subidhya Shrestha ◽  
Jonathan Neubauer ◽  
Rebecca Spanner ◽  
Mari Natwick ◽  
Joshua Rios ◽  
...  
Keyword(s):  
Sugar Beet ◽  
Fungicide Resistance ◽  
Rapid Detection ◽  
Lamp Assay ◽  
Qpcr Assay ◽  
Cercospora Beticola ◽  
Lamp Method ◽  
In Planta ◽  
Cercospora Leaf Spot

Cercospora leaf spot (CLS), caused by the fungal pathogen Cercospora beticola, is the most destructive disease of sugar beet worldwide. Although growing CLS-tolerant varieties is helpful, disease management currently requires timely application of fungicides. However, overreliance on fungicides has led to the emergence of fungicide resistance in many C. beticola populations, resulting in multiple epidemics in recent years. Therefore, this study focused on developing a fungicide resistance detection “toolbox” for early detection of C. beticola in sugar beet leaves and mutations associated with different fungicides in the pathogen population. A loop-mediated isothermal amplification (LAMP) method was developed for rapid detection of C. beticola in infected sugar beet leaves. The LAMP primers specific to C. beticola (Cb-LAMP) assay was able to detect C. beticola in inoculated sugar beet leaves as early as 1 day postinoculation. A quinone outside inhibitor (QoI)-LAMP assay was also developed to detect the G143A mutation in cytochrome b associated with QoI resistance in C. beticola. The assay detected the mutation in C. beticola both in vitro and in planta with 100% accuracy. We also developed a probe-based quantitative PCR (qPCR) assay for detecting an E198A mutation in β-tubulin associated with benzimidazole resistance and a probe-based qPCR assay for detection of mutations in cytochrome P450-dependent sterol 14α-demethylase (Cyp51) associated with resistance to sterol demethylation inhibitor fungicides. The primers and probes used in the assay were highly efficient and precise in differentiating the corresponding fungicide-resistant mutants from sensitive wild-type isolates.

scholarly journals Characterization of the Molecular Mechanisms of Resistance against DMI Fungicides in Cercospora beticola Populations from the Czech Republic

2021 ◽  
Vol 7 (12) ◽  
pp. 1062
Author(s):  
Ram Kumar ◽  
Jana Mazakova ◽  
Asad Ali ◽  
Vishma Pratap Sur ◽  
Madhab Kumar Sen ◽  
...  
Keyword(s):  
Gene Expression ◽  
Czech Republic ◽  
Sugar Beet ◽  
Molecular Basis ◽  
Cercospora Beticola ◽  
The Czech Republic ◽  
Fungicide Treatment ◽  
Dmi Fungicides ◽  
Dmi Resistance

Cercospora leaf spot (CLS), caused by the fungal pathogen Cercospora beticola, is the most important foliar pathogen of sugar beet worldwide. Extensive reliance on fungicides to manage CLS has resulted in the evolution of fungicide resistance in C. beticola worldwide, including populations in the Czech Republic. One important class of fungicides used to manage CLS is the sterol demethylation inhibitors (DMI). The aim of our study was to assess DMI resistance in C. beticola from the Czech Republic and elucidate the molecular basis of DMI resistance in this population. A total of 50 isolates were collected in 2018 and 2019 from the major sugar beet growing regions of the Czech Republic and assessed for in vitro sensitivity to the DMI fungicides propiconazole, prochloraz, and epoxiconazole. These analyses identified three strains that exhibited 50% effective concentration (EC50) values > 1.0 μg mL–1 against respective fungicides, which were therefore considered resistant. In contrast, strains that exhibited lowest EC50 values were considered sensitive. To explore the molecular basis of resistance in these three strains, the cytochrome P450-dependent sterol 14α-demethylase (Cyp51) gene was sequenced. Sequence analysis identified a Y464S mutation in all three resistant strains. To assess whether Cyp51 gene expression may play a role in DMI resistance, selected strains were grown in vitro with and without fungicide treatment. These analyses indicated that Cyp51 gene expression was significantly induced after fungicide treatment. Thus, we conclude that Y464S point mutation along with induced Cyp51 gene overexpression is likely responsible for resistance against DMI fungicides in C. beticola from the Czech Republic.

scholarly journals Zinc phosphate protects tomato plants against Pseudomonas syringae pv. tomato

2021 ◽  
Author(s):  
Mara Quaglia ◽  
Marika Bocchini ◽  
Benedetta Orfei ◽  
Roberto D’Amato ◽  
Franco Famiani ◽  
...  
Keyword(s):  
Disease Severity ◽  
Pseudomonas Syringae ◽  
Zinc Phosphate ◽  
Plant Defence ◽  
In Planta ◽  
Tomato Plants ◽  
Pathogenesis Related Protein ◽  
Defence Responses ◽  
Plant Defence Responses

AbstractThe purpose of this study was to determine whether zinc phosphate treatments of tomato plants (Solanum lycopersicum L.) can attenuate bacterial speck disease severity through reduction of Pseudomonas syringae pv. tomato (Pst) growth in planta and induce morphological and biochemical plant defence responses. Tomato plants were treated with 10 ppm (25.90 µM) zinc phosphate and then spray inoculated with strain DAPP-PG 215, race 0 of Pst. Disease symptoms were recorded as chlorosis and/or necrosis per leaf (%) and as numbers of necrotic spots. Soil treatments with zinc phosphate protected susceptible tomato plants against Pst, with reductions in both disease severity and pathogen growth in planta. The reduction of Pst growth in planta combined with significantly higher zinc levels in zinc-phosphate-treated plants indicated direct antimicrobial toxicity of this microelement, as also confirmed by in vitro assays. Morphological (i.e. callose apposition) and biochemical (i.e., expression of salicylic-acid-dependent pathogenesis-related protein PR1b1 gene) defence responses were induced by the zinc phosphate treatment, as demonstrated by histochemical and qPCR analyses, respectively. In conclusion, soil treatments with zinc phosphate can protect tomato plants against Pst attacks through direct antimicrobial activity and induction of morphological and biochemical plant defence responses.

Functional precision medicine in colorectal cancer based on patient-derived tumoroids and in-vitro sensitivity drug testing.

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. e15567-e15567
Author(s):  
Lars Henrik Jensen ◽  
Anders Kristian Moeller Jakobsen ◽  
Birgitte Mayland Havelund ◽  
Cecilie Abildgaard ◽  
Chris Vagn-Hansen ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Clinical Trial ◽  
Primary Endpoint ◽  
Drug Testing ◽  
Progression Free Survival ◽  
Patient Specific ◽  
Precision Oncology ◽  
Sensitivity Testing ◽  
In Vitro Sensitivity

e15567 Background: Precision oncology based on in-vitro, functional assays has potential advantages compared to the much more common molecular approach, but the clinical benefit is unknown. We here report the results from the largest prospective interventional clinical trial testing the clinical outcome in colorectal cancer patients treated with drugs showing cytotoxic effect in matched patient-derived tumoroids. Methods: This single-center, phase II trial included patients with metastatic colorectal cancer previously exposed to all standard therapies. Specimens from one to three 18-16 G core needle biopsies were manually dissected, enzymatically treated, cultivated, and incubated to form 3D spherical microtumors, i.e. tumoroids. In the assay for in-vitro sensitivity testing, the tumoroids were challenged with single drugs and combinations thereof to determine patient-specific responses. Using tumoroid screening technology (IndiTreat, 2cureX, Copenhagen, Denmark), results were generated by comparing the sensitivity of the individual patient’s tumoroids with a reference panel from other patients. The testing included standard cytostatics and drugs with proven effect in previous early-phase clinical trials, a total of 15 drugs. The primary endpoint was the fraction of patients with progression-free survival (PFS) at two months. Based on placebo arms in randomized last-line trials, a minimal relevant difference of 20% (20% to 40%) was stated. Using Simon's two-stage design, a sample size of 45 patients was calculated with at least 14 PFS at two months (significance 5%, power 90%). Results: Ninety patients were enrolled from 9/2017 to 9/2020. Biopsies from 82 patients were obtained and sent for tumoroid formation of which 44 (54%, 95% CI 42-65) were successful and at least one treatment was suggested. Thirty-four patients initiated treatment according to the response obtained in the drug assays within a median of 51 days from inclusion (IQR 39-63). The primary endpoint, PFS at two months, was met in 17 of 34 patients (50%, 95%CI 32-68). There were no radiological responses. Median PFS was 81 days (95% CI 51-112) and median OS was 189 days (95% CI 103-277). Conclusions: Precision oncology using a functional approach with patient-derived tumoroids and in-vitro drug sensitivity testing seems feasible. The approach is limited by the fraction of patients with successful tumoroid development. The primary endpoint was met, as half of the patients were without progression at two months. Further clinical studies are justified. Clinical trial information: NCT03251612.

scholarly journals Relationship between Acute Suppurative Otitis Media and Chronic Secretory Otitis Media: Role of Antibiotics

1984 ◽  
Vol 77 (9) ◽  
pp. 754-757 ◽  
Author(s):  
Robert Mills ◽  
Ann Uttley ◽  
Michelle McIntyre
Keyword(s):  
Otitis Media ◽  
Middle Ear ◽  
Acute Otitis Media ◽  
Secretory Otitis Media ◽  
Sensitivity Testing ◽  
Suppurative Otitis Media ◽  
In Vitro Sensitivity ◽  
Resistance To Penicillin

A total of 204 chronic middle ear effusions from 122 children have been studied. Bacteria were isolated from 30 effusions. The commonest species found were Strep. pneumoniae and H. influenzae. These are also the commonest organisms causing acute otitis media (AOM). A similar pattern of serotypes was also demonstrated. In vitro sensitivity testing showed that most of the organisms isolated were sensitive to most commonly-used antibiotics. The main exception was resistance to penicillin amongst strains of H. influenzae and Staph. aureus. It is suggested that some cases of chronic secretory otitis media (SOM) may arise as a result of incomplete resolution of AOM and that the use of penicillin to treat AOM may be one factor in this process.

scholarly journals Improvement of the technology of obtaining stable (di)haploid regenerants from embryonic culture of apomictic sugar beet (Beta vulgaris) breeding material without the use of colchicine

2019 ◽  
Vol 6 (2) ◽  
pp. 3-17
Author(s):  
N. Kovalchuk ◽  
M. Roik ◽  
Ya. Hadzalo ◽  
T. Nediak ◽  
O. Zinchenko
Keyword(s):  
Sugar Beet ◽  
Seed Production ◽  
Embryo Culture ◽  
Direct Regeneration ◽  
Genetic Determination ◽  
Alloplasmic Lines ◽  
Cultural Medium ◽  
Wide Range ◽  
Regenerant Plants

Aim. To evaluate the effi ciency of inducing generative, reduced parthenogenesis and to better use the differentiating potential of the embryo culture under apomictic seed production in selection materials of sugar beet with cytoplasmic male sterility (CMS), and B) to isolate homozygous lines (dihaploids) without the use of polyploidizing substances. Methods. Apomictic (agamosper- mous) seed production in apocarpous pollen sterile lines from B. vulgaris subsp. vulgaris var. altissima (sugar beet) using classi- cal so-called Owen sterile cytoplasm and sterile cytoplasm from Beta maritimа and Beta patula as sources, was conducted under pollen free conditions and spatial isolation in the greenhouse breeding complex of the Yaltushkivska experimental breeding station (Yaltushki, Ukraine). The specifi cities of embryonic development of apomictic embryos were studied with the purpose of effi cient regulation of the induction of explants in vitro as donors of the culture of immature embryos. Fluorescent fl ow cytophotometry in combination with the computer program of the Partec Ploidy Analyser PA-2 (Partec GmbH, Germany, now Sysmex), were used to determine the degree of ploidy, enabling the selection of haploid and dihaploid lines in vitro. A genetic method was developed using the expression of morphological marker indices of nuclear genes of anthocyanin coloring (R+ r–) of regenerant plants in vitro and ploidy determination for differentiation by generative (reduced) parthenogenesis. The sampling technique that took into account the hormonal composition of cultural media and the level of genome ploidy, sample frequency and statistical analysis of the results was determined using the appropriate statistics; the percentage of regenerants, induced by different types of morpho- genesis and ploidy in vitro, was determined along with the measurement error to control the accuracy of the selected sampling (number of seed embryos). Results. The selected cultural medium No. 3, based on the basal medium according to Gamberg et al., 1968 (21), contained 6 BAP – 2 mg/l, 2.4 D – 0.5 mg/l, gibberellic acid – 0.1 mg/l, which ensured a success rate of 4.4 to 23.3 % of direct regeneration of shoots from the embryo culture, depending on the genotype of donors, and 4–10 % for induction and proliferation of callus. In ten experimental numbers of alloplasmic lines of sugar beet, the incidence of haploids and mixoploids among the regenerants from the embryo culture fl uctuated within the wide range of 14.8 – 62.2 % and exceeded the indices, ob- tained by other known methods of haploid parthenogamy, which had the values of 3.79 – 6.25 %. Conclusions. The homozygous lines and dihaploids were determined and set apart/stabilized in the process of micropropagation, where the differentiation of clones was made on the basis of total DNA content in interphase nuclei, using information of histograms generated in fl uorescent fl ow cytometry with the Partec Ploidy Analyser PA-II instrumentation. The medium, based on macro- and microsalts according to Gamberg et al., 1968 (21) was found to be the most effi cient; it ensured at least partially successful direct regeneration in the culture of embryos within the range of 4.40 ± 1.29 to 23.3 ± 3.45 %. The success of direct regeneration of apomictic material depended on the composition of the cultural medium used fi rst and foremost, and to a lesser extent on the stages of embryogenesis from day 12 till day 32, differentiated by the fi xation period for seed embryos starting from the beginning of fl owering. Homozygous lines were created without polyploid-inducing substances due to spontaneous transfer of some cells of haploid regenerant plants to a higher level of ploidy, that can be used in the breeding of sugar beet. Genetic determination of apomictic seed reproduction in alloplasmic lines and pollen free lines of sugar beet and the technologies of inducing dihaploids allow reducing the period of inzucht-crossing considerably to obtain homozygous lines, creating unique material for chromosome engineering and marker-oriented selection with target combinations of genes in homozygous state.

Diagnosis, treatment, and temporary remission of disseminated paecilomycosis in a vizsla

1996 ◽  
Vol 32 (6) ◽  
pp. 509-514 ◽  
Author(s):  
PA March ◽  
K Knowles ◽  
CL Dillavou ◽  
R Jakowski ◽  
G Freden
Keyword(s):  
Central Nervous System ◽  
Bone Marrow ◽  
Marked Improvement ◽  
Clinical Signs ◽  
Central Nervous System Involvement ◽  
Disease Course ◽  
Sensitivity Testing ◽  
In Vitro Sensitivity ◽  
Multisystemic Disease

A case of disseminated paecilomycosis in a three-year-old vizsla is described. Clinical signs of lethargy, weight loss, lymphadenopathy, diarrhea, and vestibulocochlear deficits were exhibited. Dense colonization of bone marrow by the fungus was found early in the disease course. Serial culture of bone-marrow aspirates and in vitro sensitivity testing helped monitor disease progression and guide antifungal therapy. Clinical and laboratory parameters demonstrated marked improvement for a period of 12 weeks. Multisystemic disease with central nervous system involvement was found at necropsy.

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