scholarly journals Spatial and Temporal Sensitivity of Alternaria Species Associated With Potato Foliar Diseases to Demethylation Inhibiting and Anilino-Pyrimidine Fungicides

Plant Disease ◽  
2016 ◽  
Vol 100 (9) ◽  
pp. 1848-1857 ◽  
Author(s):  
D. L. Fonseka ◽  
N. C. Gudmestad
Keyword(s):  
Fungal Growth ◽  
Alternaria Solani ◽  
Potato Production ◽  
Brown Spot ◽  
Intrinsic Activity ◽  
In Vitro Assays ◽  
Baseline Sensitivity ◽  
Foliar Diseases

Early blight and brown spot, caused by Alternaria solani and Alternaria alternata, respectively, are important foliar diseases of potato, affecting both tuber yield and quality. Most of the commercial cultivars lack resistance; therefore, the application of foliar fungicides remains a primary disease management strategy. Baseline sensitivities of A. solani to difenoconazole and metconazole (demethylation inhibitors) using mycelial growth assay exhibited similar intrinsic activity against the pathogen with mean EC50 (the effective concentration at which the fungal growth is inhibited by 50%) values of 0.09 μg/ml. However, the sensitivity of individual baseline A. solani isolates to each fungicide varied substantially, resulting in very low and nonsignificant correlation coefficients among fungicides. Mean EC50 values for baseline A. alternata isolates in response to difenoconazole and metconazole were 0.14 and 0.26 μg/ml, respectively. The sensitivity of the majority of A. solani and A. alternata isolates collected from 2010 to 2014 from various potato production states was consistent with baseline isolates, therefore, these potato pathogens remain sensitive to the two demethylation inhibitor chemistries used to manage it. Baseline sensitivity assays of pyrimethanil (anilino-pyrimidine) also indicated great intrinsic activity against both foliar pathogens with mean EC50 values of 0.44 and 0.35 μg/ml for A. solani and A. alternata, respectively. Although A. alternata remains largely sensitive to pyrimethanil, 6 out of 245 A. solani isolates collected from 2010 to 2014 exhibited reduced-sensitivity to the fungicide in in vitro assays. Reduced-sensitive isolates were not controlled at most pyrimethanil doses except at 100 μg/ml in greenhouse in vivo efficacy tests. These chemistries remain valuable options for fungicide rotation programs in areas of high disease pressure.

Impact of SDH Mutations in Alternaria solani on Recently Developed SDHI Fungicides Adepidyn and Solatenol

Plant Disease ◽  
2021 ◽  
Author(s):  
Sarah Rodriguez ◽  
Rhodesia Celoy ◽  
Ipsita Mallik ◽  
Julie Sherman Pasche ◽  
Neil C Gudmestad
Keyword(s):  
Early Blight ◽  
Field Experiments ◽  
Alternaria Solani ◽  
Potato Production ◽  
Field Trials ◽  
Intrinsic Activity ◽  
In Vitro Assays ◽  
Commercial Application ◽  
Quinone Outside Inhibitor

Early blight, caused by Alternaria solani, is observed annually in all midwestern potato production areas. The use of foliar fungicides remains a primary management strategy. However, A. solani has developed reduced-sensitivity or resistance to many single-site fungicides such as quinone outside inhibitor (QoI, FRAC group 11), succinate dehydrogenase inhibitor (SDHI, FRAC group 7), demethylation inhibitors (DMI, FRAC group 3), and anilinopyrimidine (AP, FRAC group 9) fungicides. Boscalid, fluopyram, solatenol, and adepidyn are EPA-registered SDHI fungicides used commercially on a variety of crops, including potato. Five SDH mutations have been characterized previously in A. solani that affect the efficacy of boscalid while only one of these mutations has been demonstrated to negatively affect fluopyram efficacy. Conidial germination assays were used to determine if a shift in sensitivity has occurred in these SDHI fungicides. Alternaria solani isolates collected prior to the commercial application of SDHI fungicides (baseline) and were compared to recently collected isolates (non-baseline). Greenhouse evaluations were conducted also to evaluate the efficacy of boscalid, fluopyram, solatenol, and adepidyn on A. solani isolates possessing individual SDH mutations. Additionally, field trials were conducted to determine the effects application of these SDHI fungicides on the frequency of SDH mutations. Fluopyram, solatenol, and adepidyn had high intrinsic activity against A. solani when compared to boscalid, based on in vitro assays. The application of adepidyn and solatenol resulted in greater early blight control than the application of boscalid and fluopyram in greenhouse experiments. Molecular characterization of A. solani isolates collected from the field trials determined that the frequency of the H134R-mutation can increase in response to more recently developed SDHI fungicides. In contrast, the H278R/Y- and H133R-mutations decreased to the point of being nearly absent in these field experiments.

scholarly journals Waktu Inkubasi pada Derajat Distilasi Kitosan Enzim dan Efektifitas Penghambatannya terhadap Penyakit Antraknosa

2017 ◽  
Vol 12 (6) ◽  
pp. 209
Author(s):  
Yadi Suryadi ◽  
Tri Puji Priyatno ◽  
I Made Samudra ◽  
Dwi Ningsih Susilowati ◽  
Hermawati Nurzulaika ◽  
...  
Keyword(s):  
Spore Germination ◽  
Burkholderia Cepacia ◽  
Fungal Growth ◽  
The Other ◽  
In Vitro Assays ◽  
Incubation Condition ◽  
Coating Agent ◽  
Optimal Incubation

The use of chitosan as a coating agent of harvested fruits is an alternative method in controlling anthracnose disease (Colletotrichum sp.). This study aimed to obtain an optimal enzymatic chitosan (EC) that hydrolyzed using chitinase from Burkholderia cepacia isolate E76. The optimal incubation condition to produce EC was 2 h with the yield of 3.52 ± 0.38 g. The degree of deacetylation (DD) chitosan and  EC was 66.91% and 80.91%, respectively. Based on in vitro assays, EC 2% was the most effective in inhibiting the growth of Colletotrichum sp. (94.22%)  than chitosan, while the highest inhibition for chitosan 3% was 55.26%. Moreover, the EC 2% showed the highest inhibition of spore germination (74.12%). The in vivo assay revealed that EC 2% showed the highest inhibition on the fungal growth (88.88%), compared to the other concentrations. On the other hand, the EC 2% and 3% gave similar results on inhibition of Colletotrichum sp.of chili (55.55%). 

scholarly journals Potential Application of Propolis Extracts to Control the Growth of Stemphylium vesicarium in “Rocha” Pear

2020 ◽  
Vol 10 (6) ◽  
pp. 1990 ◽  
Author(s):  
Marcella Loebler ◽  
Claudia Sánchez ◽  
Elisabete Muchagato Maurício ◽  
Eugénio Diogo ◽  
Mário Santos ◽  
...  
Keyword(s):  
Disease Incidence ◽  
Brown Spot ◽  
In Vitro Assays ◽  
Economic Losses ◽  
Yield Reduction ◽  
Stemphylium Vesicarium ◽  
Spot Disease ◽  
Brown Spot Disease

Stemphylium vesicarium (Wallr.) E. G. Simmons is the pathogen responsible of brown spot disease in pear and has become one of the main concerns for European pear producers. In Portugal, S. vesicarium is responsible for significant yield reduction and economic losses in “Rocha” pear (Pyrus communis L. cv Rocha) production. Considering the antimicrobial potential of propolis, the high incidence of brown spot in pears and the emergence of fungicides resistance in S. vesicarium, this study aimed to evaluate the potential of Portuguese propolis as an alternative strategy to control brown spot disease in “Rocha” pear. In vitro assays showed that propolis extracts were able to inhibit up to 90% the S. vesicarium mycelial growth. In vivo assays in artificially wounded and inoculated “Rocha” pears showed that, compared to the control, the disease incidence decreased up to 25% and the lesions diameter up to 57%, in fruits treated with propolis. Moreover, propolis seems to be more efficient in reducing the disease incidence when applied after pathogen inoculation (curative assay) than when applied before pathogen inoculation (prophylactic assay). Thus, the results suggest that propolis extracts have potential to be applied as part of an integrated approach for the control of brown spot of pear.

scholarly journals Potential Impact of Fluopyram on the Frequency of the D123E Mutation in Alternaria solani

Plant Disease ◽  
2018 ◽  
Vol 102 (3) ◽  
pp. 656-665 ◽  
Author(s):  
Mitchell J. Bauske ◽  
S. K. R. Yellareddygari ◽  
Neil C. Gudmestad
Keyword(s):  
Disease Control ◽  
Solanum Tuberosum L ◽  
Management Strategies ◽  
Point Mutations ◽  
Fungal Growth ◽  
Alternaria Solani ◽  
Selective Advantage ◽  
Field Trials

Succinate dehydrogenase-inhibiting (SDHI) fungicides have been widely applied in commercial potato (Solanum tuberosum L.) fields for the control of early blight, caused by Alternaria solani Sorauer. Five-point mutations on three AsSdh genes in A. solani have been identified as conferring resistance to SDHI fungicides. Recent work in our laboratory determined that A. solani isolates possessing the D123E mutation, or the substitution of aspartic acid for glutamic acid at position 123 in the AsSdhD gene, were collected at successively higher frequencies throughout a 3-year survey. In total, 118 A. solani isolates previously characterized as possessing the D123E mutation were evaluated in vitro for boscalid and fluopyram sensitivity. Over 80% of A. solani isolates with the D123E mutation evaluated were determined to be highly resistant to boscalid in vitro. However, effective concentration at which the fungal growth is inhibited by 50% values of isolates with the D123E mutation to fluopyram, ranging from 0.2 to 3 µg/ml, were sensitive and only slightly higher than those of baseline isolates to fluopyram, which ranged from 0.1 to 0.6 µg/ml. Five A. solani isolates with the D123E mutation were further evaluated in vivo for percent disease control obtained from boscalid and fluopyram compared with two wild-type isolates, three isolates possessing the F129L mutation, two isolates possessing the H134R mutation, two isolates possessing the H133R mutation, and one isolate with the H278R mutation. Relative area under the dose response curve values for boscalid and fluopyram were significantly lower for all five D123E-mutant isolates, demonstrating reduced disease control in vivo. In field trials, the frequency of A. solani isolates with the D123E mutation recovered from treatments receiving an in-furrow application of fluopyram ranged from 5 to 37%, which was significantly higher compared with treatments receiving foliar applications of standard protectants, in which the frequency of the D123E mutation in isolates ranged from 0 to 2.5%. Results suggest that A. solani isolates possessing the D123E mutation have a selective advantage under the application of fluopyram compared with SDHI-sensitive isolates, as well as isolates possessing other mutations conferring SDHI resistance. These data illustrate the importance of implementing fungicide resistance management strategies and cautions the use of fluopyram for in-furrow applications that target other pathogens of potato.

scholarly journals Prevalence and Impact of SDHI Fungicide Resistance in Alternaria solani

Plant Disease ◽  
2013 ◽  
Vol 97 (7) ◽  
pp. 952-960 ◽  
Author(s):  
N. C. Gudmestad ◽  
S. Arabiat ◽  
J. S. Miller ◽  
J. S. Pasche
Keyword(s):  
Fungicide Resistance ◽  
Early Blight ◽  
Alternaria Solani ◽  
Significant Loss ◽  
Intrinsic Activity ◽  
Wild Type ◽  
Baseline Sensitivity ◽  
Disease Pressure ◽  
Moderately Resistant

Early blight, caused by Alternaria solani, is an important chronic foliar disease of potato (Solanum tuberosum) present every growing season in the Midwestern United States. Most currently grown potato cultivars lack resistance to early blight; therefore, foliar fungicides are relied upon for disease management. Foliar fungicides with high efficacy against the pathogen, such as boscalid, frequently are used under high disease pressure situations, such as potatoes grown under overhead irrigation. Boscalid is a member of the succinate dehydrogenase inhibiting (SDHI) fungicide group and was registered for use on potato in 2005. Baseline sensitivity of A. solani to the SDHI fungicides boscalid, penthiopyrad, and fluopyram using a spore germination assay demonstrated similar intrinsic activity against A. solani with mean EC50 values of 0.33, 0.38, and 0.31 μg/ml, respectively. However, isolates varied in their sensitivity to each of these fungicides, resulting in very low correlations (r) among isolate sensitivity to each fungicide. Resistance to boscalid in A. solani was detected in the states of North Dakota, Minnesota, Nebraska, Texas, Idaho, Wisconsin, and Florida from early blight samples collected in 2010 and 2011. Two phenotypes of boscalid resistance were detected. Approximately 80% of all A. solani assayed were found to have some level of resistance to boscalid with about 5 and 75% of the population moderately resistant (5 to 20 μg/ml) and highly resistant (>20 μg/ml), respectively, to the fungicide. Nearly 99% of all boscalid resistant isolates possessed the F129L mutation in the cytrochrome b gene, indicating that an A. solani population with dual fungicide resistance predominates in the states surveyed. However, A. solani isolates resistant to boscalid remained sensitive to fluopyram, and a large proportion of moderately resistant and resistant isolates were sensitive to penthiopyrad. Disease control data from in vivo trials demonstrated a significant loss of fungicide efficacy when boscalid and fluxapyroxad were used to control moderately and highly resistant isolates of A. solani relative to the control these fungicides provided wild-type isolates. Fluopyram, however, controlled boscalid resistant isolates as well as it controlled wild-type isolates of A. solani. These data will assist potato growers in regions where boscalid resistance is prevalent by assisting them in avoiding fungicides that do not effectively control early blight and in selecting SDHI fungicide molecules that remain efficacious.

scholarly journals Shift in Sensitivity of Alternaria solani in Response to QoI Fungicides

Plant Disease ◽  
2004 ◽  
Vol 88 (2) ◽  
pp. 181-187 ◽  
Author(s):  
J. S. Pasche ◽  
C. M. Wharam ◽  
N. C. Gudmestad
Keyword(s):  
Disease Severity ◽  
Spore Germination ◽  
Early Blight ◽  
Alternaria Solani ◽  
Baseline Sensitivity ◽  
Qoi Fungicides ◽  
Cross Sensitivity ◽  
Significant Difference

Isolates of Alternaria solani, cause of potato early blight, collected in 1998 through 2001 from various potato growing areas across the midwestern United States, were tested for sensitivity to azoxystrobin. Isolates collected in 1998, prior to the introduction of azoxystrobin, were tested to establish the baseline sensitivity of the fungus to this fungicide. Isolates collected in subsequent years, not necessarily from the same sites as baseline isolates, were tested to determine if populations of A. solani had become less sensitive to azoxystrobin. Azoxystrobin sensitivity was determined utilizing an in vitro spore germination assay. The effective fungicide concentration that inhibited spore germination by 50% (EC50) was determined for each isolate. There was no significant difference in mean EC50 values between baseline isolates and all other isolates collected through 1999. Mean azoxystrobin EC50 values of A. solani isolates collected in 2000 and 2001 were significantly higher compared with means from previous years, and mean azoxystrobin EC50 values from 2001 were significantly higher than means from isolates collected in 2000. A subset of 54 A. solani isolates was evaluated in vitro for cross-sensitivity to pyraclostrobin and trifloxystrobin. A highly significant and strong correlation among the isolates tested for fungicide cross-sensitivity was detected between azoxystrobin and pyraclostrobin; however, the correlation between azoxystrobin and trifloxystrobin, and between trifloxystrobin and pyraclostrobin, was significant but weak. A second subset of five isolates was chosen for in vivo assessment of azoxystrobin, pyraclostrobin, and trifloxystrobin sensitivity. Disease severity on plants treated with azoxystrobin and pyraclostrobin was significantly greater with reduced-sensitive A. solani isolates compared with sensitive isolates. Disease severity was not statistically different between azoxystrobin reduced-sensitive and sensitive A. solani isolates on plants treated with trifloxystrobin. This is the first report of a shift in sensitivity to QoI fungicides in a fungus possessing only an anamorphic stage.

A in Vivo Assay for Standardizing Heparin Preparations

1979 ◽  
Vol 41 (03) ◽  
pp. 576-582
Author(s):  
A R Pomeroy
Keyword(s):  
In Vitro Assays ◽  
British Pharmacopoeia ◽  
In Vitro Method ◽  
Standard Preparation ◽  
Reliable Estimation ◽  
Assay Procedure ◽  
Accuracy And Precision ◽  
Heparin Preparation

SummaryThe limitations of currently used in vitro assays of heparin have demonstrated the need for an in vivo method suitable for routine use.The in vivo method which is described in this paper uses, for each heparin preparation, four groups of five mice which are injected intravenously with heparin according to a “2 and 2 dose assay” procedure. The method is relatively rapid, requiring 3 to 4 hours to test five heparin preparations against a standard preparation of heparin. Levels of accuracy and precision acceptable for the requirements of the British Pharmacopoeia are obtained by combining the results of 3 to 4 assays of a heparin preparation.The similarity of results obtained the in vivo method and the in vitro method of the British Pharmacopoeia for heparin preparations of lung and mucosal origin validates this in vivo method and, conversely, demonstrates that the in vitro method of the British Pharmacopoeia gives a reliable estimation of the in vivo activity of heparin.

Potentially Thrombogenic Materials in Factor IX Concentrates

1975 ◽  
Vol 33 (03) ◽  
pp. 617-631 ◽  
Author(s):  
H. S Kingdon ◽  
R. L Lundblad ◽  
J. J Veltkamp ◽  
D. L Aronson
Keyword(s):  
Human Plasma ◽  
Antithrombin Iii ◽  
Factor Ix ◽  
In Vitro Assays ◽  
Substantial Agreement ◽  
Coefficient Of Correlation

SummaryFactor IX concentrates manufactured from human plasma and intended for therapeutic infusion in man have been suspected for some time of being potentially thrombogenic. In the current studies, assays were carried out in vitro and in vivo for potentially thrombogenic materials. It was possible to rank the various materials tested according to the amount of thrombogenic material detected. For concentrates not containing heparin, there was substantial agreement between the in vivo and in vitro assays, with a coefficient of correlation of 0.77. There was no correlation between the assays for thrombogenicity and the antithrombin III content. We conclude that many presently available concentrates of Factor IX contain substantial amounts of potentially thrombogenic enzymes, and that this fact must be considered in arriving at the decision whether or not to use them therapeutically.

In-silico Studies of Isolated Phytoalkaloid Against Lipoxygenase: Study Based on Possible Correlation

2018 ◽  
Vol 21 (3) ◽  
pp. 215-221
Author(s):  
Haroon Khan ◽  
Muhammad Zafar ◽  
Helena Den-Haan ◽  
Horacio Perez-Sanchez ◽  
Mohammad Amjad Kamal
Keyword(s):  
In Silico ◽  
Docking Studies ◽  
In Vivo Studies ◽  
In Vitro Assays ◽  
Chronic Obstructive ◽  
Lipoxygenase Inhibitors ◽  
Lipoxygenase Inhibition ◽  
In Silico Studies

Aim and Objective: Lipoxygenase (LOX) enzymes play an important role in the pathophysiology of several inflammatory and allergic diseases including bronchial asthma, allergic rhinitis, atopic dermatitis, allergic conjunctivitis, rheumatoid arthritis and chronic obstructive pulmonary disease. Inhibitors of the LOX are believed to be an ideal approach in the treatment of diseases caused by its over-expression. In this regard, several synthetic and natural agents are under investigation worldwide. Alkaloids are the most thoroughly investigated class of natural compounds with outstanding past in clinically useful drugs. In this article, we have discussed various alkaloids of plant origin that have already shown lipoxygenase inhibition in-vitro with possible correlation in in silico studies. Materials and Methods: Molecular docking studies were performed using MOE (Molecular Operating Environment) software. Among the ten reported LOX alkaloids inhibitors, derived from plant, compounds 4, 2, 3 and 1 showed excellent docking scores and receptor sensitivity. Result and Conclusion: These compounds already exhibited in vitro lipoxygenase inhibition and the MOE results strongly correlated with the experimental results. On the basis of these in vitro assays and computer aided results, we suggest that these compounds need further detail in vivo studies and clinical trial for the discovery of new more effective and safe lipoxygenase inhibitors. In conclusion, these results might be useful in the design of new and potential lipoxygenase (LOX) inhibitors.

Discovery of 3-Cinnamamido-N-Substituted Benzamides as Potential Antimalarial Agents

2020 ◽  
Vol 16 ◽  
Author(s):  
Haicheng Liu ◽  
Yushi Futamura ◽  
Honghai Wu ◽  
Aki Ishiyama ◽  
Taotao Zhang ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Antimalarial Activity ◽  
In Vitro Assays ◽  
Compound Library ◽  
Antimalarial Agents ◽  
Phenotypic Screen ◽  
Ic50 Values ◽  
Substituted Benzamides

Background: Malaria is one of the most devastating parasitic diseases, yet the discovery of antimalarial agents remains profoundly challenging. Very few new antimalarials have been developed in the past 50 years, while the emergence of drug-resistance continues to appear. Objective: This study focuses on the discovery, design, synthesis, and antimalarial evaluation of 3-cinnamamido-N-substituted benzamides. Method: In this study, a screening of our compound library was carried out against the multidrug-sensitive Plasmodium falciparum 3D7 strain. Derivatives of the hit were designed, synthesized and tested against P. falciparum 3D7 and the in vivo antimalarial activity of the most active compounds was evaluated using the method of Peters’ 4-day suppressive test. Results: The retrieved hit compound 1 containing a 3-cinnamamido-N-substituted benzamide skeleton showed moderate antimalarial activity (IC50 = 1.20 µM) for the first time. A series of derivatives were then synthesized through a simple four-step workflow, and half of them exhibited slightly better antimalarial effect than the precursor 1 during the subsequent in vitro assays. Additionally, compounds 11, 23, 30 and 31 displayed potent activity with IC50 values of approximately 0.1 µM, and weak cytotoxicity against mammalian cells. However, in vivo antimalarial activity is not effective which might be ascribed to the poor solubility of these compounds. Conclusion: In this study, phenotypic screen of our compound library resulted in the first report of 3-cinnamamide framework with antimalarial activity and 40 derivatives were then designed and synthesized. Subsequent structure-activity studies showed that compounds 11, 23, 30 and 31 exhibited the most potent and selective activity against P. falciparum 3D7 strain with IC50 values around 0.1 µM. Our work herein sets another example of phenotypic screen-based drug discovery, leading to potentially promising candidates of novel antimalarial agents once given further optimization.

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