Prevention and Detection of Fungicide Resistance Development in Rhizoctonia zeae from Soybean and Corn in Nebraska

2021 ◽  
Author(s):  
Nikita Gambhir ◽  
Srikanth Kodati ◽  
Matthew Huff ◽  
Flávio Silva ◽  
Olutoyosi Ajayi-Oyetunde ◽  
...  
Keyword(s):  
Fungicide Resistance ◽  
Resistance Management ◽  
Dry Weight ◽  
Geographic Region ◽  
Population Characteristics ◽  
Current Status ◽  
In Planta ◽  
Resistance Development ◽  
Rhizoctonia Zeae

The goal of this research was to advance the foundational knowledge required to quantify and mitigate fungicide resistance in Rhizoctonia zeae, the seedling disease pathogen of soybean and corn. In vitro sensitivity to azoxystrobin, fludioxonil, sedaxane, and/or prothioconazole was determined for 91 R. zeae isolates obtained mostly from soybean and corn fields in Nebraska. Isolates were sensitive to fludioxonil, sedaxane, and prothioconazole (EC50 < 3 µg/ml) and had a positively skewed EC50 distribution. Isolates were not sensitive to azoxystrobin in vitro (EC50 > 100 µg/ml) or in planta. Application of azoxystrobin did not significantly decrease disease severity or improve total dry weight of the soybean plants (P > 0.05). The risk of resistance development in R. zeae was estimated by characterizing its population structure. Eighty-one R. zeae isolates were genotyped using six microsatellite markers. Results showed that the population has a mixed mode of reproduction and is structured according to geographic region, suggesting limited dispersal. These population characteristics suggest that R. zeae has an intermediate risk of resistance development. Overall, this research established the current status of fungicide sensitivity in R. zeae in Nebraska and estimated its risk of resistance development, which can inform fungicide resistance management for R. zeae.

scholarly journals Succinate dehydrogenase inhibitor (SDHI) fungicide resistance prevention strategy

2011 ◽  
Vol 64 ◽  
pp. 119-124 ◽  
Author(s):  
A.H. McKay ◽  
G.C. Hagerty ◽  
G.B. Follas ◽  
M.S. Moore ◽  
M.S. Christie ◽  
...  
Keyword(s):  
New Zealand ◽  
High Risk ◽  
Succinate Dehydrogenase ◽  
Fungicide Resistance ◽  
Fungal Pathogens ◽  
Resistance Management ◽  
Resistance Development ◽  
Development Of Resistance ◽  
Action Committee ◽  
Succinate Dehydrogenase Inhibitor

Succinate dehydrogenase inhibitor (SDHI) fungicides are currently represented in New Zealand by eight active ingredients bixafen boscalid carboxin fluaxapyroxad fluopyram isopyrazam penthiopyrad and sedaxane They are either currently registered or undergoing development in New Zealand for use against a range of ascomycete and basiodiomycete pathogens in crops including cereals ryegrass seed apples pears grapes stonefruit cucurbits and kiwifruit These fungicides are considered to have medium to high risk of resistance development and resistance management is recommended by the Fungicide Resistance Action Committee (FRAC) in Europe Guidelines are presented for use of SDHI fungicides in New Zealand to help avoid or delay the development of resistance in the fungal pathogens that they target

scholarly journals CURRENT STATUS OF TRANSGENIC COTTON-UTILITY OF GENOTYPE INDEPENDENT IN PLANTA APPROACHES FOR THE GENERATION OF TRANSGENICS

2020 ◽  
Vol 11 (2) ◽  
Author(s):  
Kesiraju Karthik
Keyword(s):  
Tissue Culture ◽  
In Vitro Regeneration ◽  
Crop Improvement ◽  
Transgenic Cotton ◽  
Current Status ◽  
In Planta ◽  
Biotic And Abiotic Stresses ◽  
Independent Manner ◽  
Gossypium Spp

Cotton (Gossypium spp.), is a mercantile crop plant is grown for its fluffy fiber and cotton seed oil in around 70 countries worldwide. Cotton is an economically important crop, shows erratic productivity under rain feed conditions; it is bogged down with many biotic and abiotic stresses. Due to lack of resistant germplasm, crop improvement through conventional breeding practices has been lagging. Genetic engineering offers numerous protocols to engineer plants to overcome stress. Biotechnological intervention for cotton improvement has begun three decades ago. The recalcitrance of cotton to tissue culture has been the major constraint for in vitro regeneration. Alternate methods that evade tissue culture regeneration steps have thus been envisaged. Till date there are very few standardized protocols that can be employed to develop transgenics in a genotype independent manner. Thus, genotype independent in planta transformation strategies have gained momentum in the present days, but reproducibility of reported protocols remains an amigna in many cases. In planta transformations holds prominence due to viability and ease in generation of transgenic cotton plants with in less time. This review focuses on grouping efforts made by different research groups in this senior. Several reports and standardizations have been focused that reports development of transgenic cotton.

Fungicide resistance in Venturia effusa, cause of pecan scab: current status and practical implications

2020 ◽  
Author(s):  
Jeff Standish ◽  
Tim Brenneman ◽  
Clive Bock ◽  
Katherine Stevenson
Keyword(s):  
Fungicide Resistance ◽  
Operating Cost ◽  
Resistance Management ◽  
Research Priorities ◽  
Current Status ◽  
Future Research ◽  
Pecan Scab ◽  
Recent Developments ◽  
Benzimidazole Carbamates ◽  
Practical Implications

Pecan scab, caused by Venturia effusa, is the most economically damaging disease of pecan in the southeastern U.S. and annual epidemics are most effectively managed through multiple fungicide applications. The fungicide applications can be the single greatest operating cost for commercial growers and the return on that investment is impacted by fungicide resistance. Venturia effusa produces multiple generations of conidia per season, exhibits substantial genetic diversity, overwinters as stromata in the tree, and is under immense selection from the applied fungicides, all of which lead to a high risk for developing fungicide resistance. Since the mid-1970s, resistance or reduced sensitivity has been observed in isolates of V. effusa to the methyl benzimidazole carbamates, demethylation inhibitors, quinone outside inhibitors, organotin compounds and the guanidines. Over the last ten years, several studies have been conducted that have improved both scab management and fungicide resistance management in V. effusa. The aim of this review is to summarize recent developments in our understanding of fungicide resistance in V. effusa in the context of scab management in southeastern pecan orchards. The history, modes of action, general use of the labelled fungicides, and mechanisms and stability of fungicide resistance in V. effusa are discussed; conclusions and future research priorities are also presented.

scholarly journals Improving Fungicide-Based Management of Ray Blight Disease in Tasmanian Pyrethrum Fields

Plant Disease ◽  
2008 ◽  
Vol 92 (6) ◽  
pp. 887-895 ◽  
Author(s):  
Sarah J. Pethybridge ◽  
Frank S. Hay ◽  
Tim Groom ◽  
Calum R. Wilson
Keyword(s):  
Dry Weight ◽  
Field Trials ◽  
Early Spring ◽  
Primary Objective ◽  
Canopy Reflectance ◽  
Resistance Development ◽  
Ray Blight ◽  
The Difference ◽  
Blight Disease

Ray blight disease, caused by Phoma ligulicola var. inoxydablis, is a serious threat to the Tasmanian pyrethrum industry. The management of this disease relies upon the strategic application of fungicides in early spring. A range of fungicides were assessed for their efficacy in controlling ray blight disease in Tasmanian pyrethrum fields, and the primary objective of this study was to increase fungicide options available to growers in different resistance groups. Fungicides were assessed under in vitro conditions, within five replicated-plot field trials over three seasons (2004 to 2006) and in single-plot trials over eight fields in 2005. In each of the field trials, regular assessments of disease intensity (defoliation severity and the incidence of stems with ray blight), stem height, and the number of flowers produced on each stem were made using stems as the primary sampling unit. Canopy reflectance at 830 nm and the Difference Vegetative Index, measured using a handheld multispectral radiometer, also were used to compare fungicide effects on green leaf area. The effect of fungicides on the dry weight of flowers, pyrethrin content within the flowers, flower maturity, and pyrethrin yield were determined. Under in vitro conditions, boscalid reduced both conidial germination and mycelial growth at concentrations of at least 0.16 μg/ml. In field trials 1 and 2 (in 2004), the premixed formulation of pyraclostrobin + boscalid (Pristine) increased pyrethrin yield by an average of 79% compared with nontreated plots over the two locations. Furthermore, in single-plot trials, pyraclostrobin + boscalid increased pyrethrin yield by 134 and 60% compared with the industry-recommended protocol (single application of azoxystrobin at 150 g a.i./ha [Amistar WG] and two additional applications of a tank mixture of difenoconazole at 125 g a.i./ha [Score] and chlorothalonil at 1,008 liters a.i./ha [Bravo 720] at 14- to 21-day intervals) and nontreated plots, respectively. In field trials 3 (in 2005) and 4 and 5 (in 2006), similar yield benefits also were produced by applying pyraclostrobin (Cabrio SC) or boscalid (Filan) alone or in combination with chlorothalonil (Bravo 720) at 1.4 liters of product per hectare, regardless of the rates of pyraclostrobin (250 and 125 g a.i./ha) and boscalid (500 and 250 g a.i./ha) used. These data were used to recommend the incorporation of boscalid to improve the fungicide-based management of ray blight disease. This decreases the number of applications of both strobilurin and triazole fungicides which have been used extensively for the management of ray blight and other diseases in Tasmanian pyrethrum fields and are prone to fungicide resistance development.

scholarly journals Carboxylic acid amide (CAA) fungicide resistance prevention strategy

2008 ◽  
Vol 61 ◽  
pp. 134-136
Author(s):  
M.S. Moore ◽  
G.B. Follas ◽  
G.C. Hagerty ◽  
R.M. Beresford
Keyword(s):  
New Zealand ◽  
Fungicide Resistance ◽  
Acid Amide ◽  
Resistance Management ◽  
Carboxylic Acid Amide ◽  
Resistance Development ◽  
Development Of Resistance ◽  
Action Committee ◽  
Medium Risk ◽  
Caa Fungicides

CAA fungicides are currently represented in New Zealand by the three active ingredients dimethomorph iprovalicarb and mandipropamid They are currently registered in New Zealand for use against oomycete fungi in grapes onions potatoes and lettuce These fungicides are considered to have low to medium risk of resistance development and resistance management is recommended by the Fungicide Resistance Action Committee (FRAC) in Europe Guidelines are presented for fungicide use that will avoid or delay the development of resistance to CAA fungicides

Identification and Characterization of Fungicide Resistance in Botrytis Populations from Small Fruit Fields in the Mid-Atlantic United States

Plant Disease ◽  
2021 ◽  
Author(s):  
Scott David Cosseboom ◽  
Mengjun Hu
Keyword(s):  
Fungicide Resistance ◽  
Multiple Drug Resistance ◽  
Resistance Management ◽  
Multiple Drug ◽  
Black Raspberry ◽  
Red Raspberry ◽  
Vitro Assay ◽  
Thiophanate Methyl ◽  
Small Fruit

From 2014 to 2019, 249 isolates of Botrytis sp. were collected from blackberry, black raspberry, grape, red raspberry, and strawberry showing gray mold symptoms. All isolates were phylogenetically characterized as Botrytis cinerea. A mycelial growth assay determined the following overall frequencies of resistance to fungicides: 92% to pyraclostrobin, 86% to cyprodinil, 71% to thiophanate-methyl, 48% to fenhexamid, 47% to iprodione, 26% to boscalid, 11% to fludioxonil, 8% to penthiopyrad, 7% to benzovindiflupyr, 4% to pydiflumetofen , and 4% to isofetamid. Isolates collected from blackberry, red raspberry, and strawberry had a higher median chemical class resistance value compared to isolates from black raspberry and grape. Resistance conferring mutations were found in a selection of isolates characterized as resistant to thiophanate-methyl, iprodione, pyraclostrobin, fenhexamid, and boscalid including E198A in β-tubulin; I365N/S, Q369P, and N373S in bos1; G143A in cytb; P238S, N369D, and F412I/S in erg27; and P225F and H272R/Y in sdhB, respectively. Also, multiple drug resistance phenotypes MDR1 and MDR1h were identified by analyzing fludioxonil sensitivity and mrr1 sequences. MDR1 and MDR1h isolates had multiple amino acid variations and two insertions in mrr1 that resembled the group S genotype . A detached grape assay confirmed that the aforementioned mutations in isolates from different small fruit crops resulted in field-relevant resistance. An additional in-vitro assay found that EC50 values of B. cinerea isolates to pydiflumetofen and inpyrfluxam averaged 0.4 and 1.0, 0.8 and 0.7, 149.8 and 23.2, 0.9 and 0.9, and 38.8 and 48.8 µg/ml for the wild-type, H272R, H272Y, N230I, and P225F genotypes, respectively. These results revealed widespread fungicide resistance in B. cinerea from Mid-Atlantic small fruit fields, highlighting the need for resistance management alternatives.

Acquisition of desiccation tolerance in developing oil palm (Elaeis guineensis Jacq.) embryos in planta and in vitro in relation to sugar content

2003 ◽  
Vol 13 (2) ◽  
pp. 179-186 ◽  
Author(s):  
Frédérique Aberlenc-Bertossi ◽  
Nathalie Chabrillange ◽  
Françoise Corbineau ◽  
Yves Duval
Keyword(s):  
Moisture Content ◽  
Oil Palm ◽  
Desiccation Tolerance ◽  
Dry Matter ◽  
Elaeis Guineensis ◽  
Dry Weight ◽  
Immature Embryos ◽  
In Planta ◽  
High Sucrose

AbstractRelationships between desiccation tolerance and dry matter, water and sugar contents were studied throughout the development of oil palm (Elaeis guineensis Jacq.) zygotic embryos and in immature embryos cultured on a sucrose-enriched medium. Embryo dry weight during in planta development increased between 80 and 140 d after pollination (DAP) and was then stable until maturity. Embryos underwent dehydration until 120 DAP, but their moisture content remained high at maturity (c. 2 g H2O g-1 DW). Desiccation tolerance was acquired between 83 and 104 DAP, and was positively correlated with embryo age and dry weight, and negatively correlated with initial water content during this period. Sucrose, the main soluble sugar present throughout embryo development, accounted for an average of 24% of the dry weight. Glucose and fructose contents decreased to less than 1 mg g-1 DW in embryos at maturity. At 117 DAP, as embryos became tolerant to desiccation, the monosaccharides/sucrose ratio fell to 0.015 and raffinose was detected. Stachyose appeared later in 147-day-old embryos and accumulated until shedding. In vitro culture of immature embryos in the presence of high sucrose concentrations (350 and 700 mM) resulted in an increase in their dry weight and a decrease in their water content, and induced the acquisition of desiccation tolerance. Under these conditions, sucrose accumulated in embryos to 30–40% on a dry weight basis, but neither raffinose nor stachyose was detected. Acquisition of desiccation tolerance by oil palm immature embryos was associated both in planta and in vitro with an accumulation of dry matter, a reduction of moisture content, and a fall in the monosaccharides/sucrose ratio. In planta, survival to dehydration was also related with the deposition of oligosaccharides whereas in vitro, it was related with high sucrose accumulation. The role of sugars in the acquisition of desiccation tolerance in oil palm embryos is discussed.

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 Pharmacological Characteristics and Efficacy of Fluazinam Against Corynespora cassiicola, Causing Cucumber Target Spot in Greenhouses

Plant Disease ◽  
2020 ◽  
Vol 104 (9) ◽  
pp. 2449-2454
Author(s):  
Tao Li ◽  
Qian Xiu ◽  
Jie Zhang ◽  
Jian Xin Wang ◽  
Ya Bing Duan ◽  
...  
Keyword(s):  
Spore Germination ◽  
Mycelial Growth ◽  
Plant Pathogens ◽  
Resistance Management ◽  
Cell Membrane Permeability ◽  
Corynespora Cassiicola ◽  
In Planta ◽  
Action Mode ◽  
Target Spot

Cucumber target spot, caused by Corynespora cassiicola, is a devastating fungal disease in greenhouses in China. Lack of resistant cultivars and unscientific use of fungicides aggravated the difficulty to manage this disease. In recent years, resistance of C. cassiicola to benzimidazoles, quinone outside inhibitors, and succinate dehydrogenase inhibitors has occurred in China. Here, we tested the fluazinam sensitivity distribution of 79 C. cassiicola isolates from different provinces in China based on mycelial growth inhibition. The EC50 values of fluazinam ranged from 0.1002 to 0.3129 µg/ml with a mean of 0.2136 ± 0.0495 µg/ml, and the sensitivity frequency was normally distributed (P = 0.2083, Shapiro–Wilk test). Meanwhile, the EC50 values for spore germination inhibition ranged from 0.0992 to 0.2278 µg/ml with a mean of 0.1499 ± 0.0504 µg/ml. This indicated that fluazinam exhibited an excellent in vitro fungicidal activity on both mycelial growth and spore germination. In addition, fluazinam also exhibited a good in planta control efficacy on detached cucumber leaves in the protective and curative assays. Moreover, the biological and physiological characteristics of C. cassiicola as affected by fluazinam were determined. Fluazinam not only significantly inhibited respiration and adenosine triphosphate production but also caused the increase of cell membrane permeability and the dysfunctions of cellular homeostasis. Interestingly, we found that fluazinam especially damaged vacuole structures, causing the redistribution of vacuole substances. Taken together, our findings provide not only essential references for resistance management of C. cassiicola but also interesting insights for further revealing the action mode of fluazinam against plant pathogens.

scholarly journals Sterol Demethylation Inhibitor Fungicide Resistance in Leptosphaeria maculans is Caused by Modifications in the Regulatory Region of ERG11

Plant Disease ◽  
2020 ◽  
Vol 104 (5) ◽  
pp. 1280-1290
Author(s):  
Yongqing Yang ◽  
Stephen J. Marcoft ◽  
Leanne M. Forsyth ◽  
Ji Zhao ◽  
Ziqin Li ◽  
...  
Keyword(s):  
Long Terminal Repeat ◽  
Fungicide Resistance ◽  
Seed Quality ◽  
Regulatory Region ◽  
Leptosphaeria Maculans ◽  
Long Terminal Repeat Retrotransposons ◽  
Terminal Repeat ◽  
In Planta ◽  
Demethylation Inhibitor

Blackleg is a worldwide disease of canola (Brassica napus), caused by a complex of fungal species in the genus Leptosphaeria, that impacts canola production and seed quality. Demethylation inhibitor (DMI) fungicides that target sterol 14α-demethylase are an integral part of disease control. Here, we report six DMI-resistant isolates of Leptosphaeria maculans and two different types of genetic modification related to the resistance. Analysis of the regulatory region of the DMI target gene ERG11 (also known as CYP51) revealed a 275-bp insertion in two of the isolates and three long terminal repeat retrotransposons (5,263, 5,267, and 5,248 bp) inserted in the promoter region of three resistant isolates. Genetic approaches confirmed that these elements are responsible for DMI resistance in L. maculans and crosses show segregation consistent with a single locus. Reverse-transcription quantitative PCR assays demonstrated that the 275-bp insertion increases ERG11 gene expression, conferring DMI fungicide resistance both in vitro and in planta. Moreover, transformation of a susceptible isolate of L. maculans with ERG11 driven by a promoter containing the 275-bp insertion increased resistance to tebuconazole. A minimal shift of the values of concentration whereby 50% of the mycelial growth is inhibited in vitro was observed in resistant isolates containing long terminal repeat retrotransposons; nevertheless, these isolates were able to develop significant lesions on cotyledons from fungicide-treated seedlings. This is the first report of genetic modifications in L. maculans relating to DMI fungicide resistance.

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