Distribution of G143A mutations conferring fungicide resistance in Virginia populations of Parastagonospora nodorum infecting wheat

2021 ◽  
Author(s):  
Navjot Kaur ◽  
Hillary Mehl
Keyword(s):  
Fungicide Resistance ◽  
Cultural Control ◽  
Target Site ◽  
Leaf Spot Disease ◽  
Site Mutation ◽  
Quinone Outside Inhibitor ◽  
Management Approaches ◽  
Pathogen Populations ◽  
Parastagonospora Nodorum ◽  
Qoi Resistance

Stagonospora nodorum blotch (SNB) caused by Parastagonospora nodorum is an important leaf spot disease in the mid-Atlantic U.S. Disease management approaches include use of resistant varieties, cultural control, and foliar fungicides. Frequent use of foliar fungicides can select for fungicide resistance within pathogen populations. Recently, the first report of quinone outside inhibitor (QoI) fungicide resistance in the U.S. was made based on a relatively small collection of P. nodorum isolates from Virginia. The objective of this study was to conduct a state-wide, two-year survey of P. nodorum populations in Virginia wheat and quantify frequencies of the target-site mutation that confers QoI resistance. A total of 318 isolates of P. nodorum were obtained from wheat collected at seven locations distributed throughout the wheat-growing regions of Virginia in 2018 and 2019. A previously designed pyrosequencing assay that detects the G143A substitution in the cytochrome b gene of P. nodorum was used to screen isolates for the presence or absence of the target site mutation. The G143A substitution was detected in all sampled fields. Among locations and years, frequencies of the mutation in P. nodorum populations ranged from 5-32% (mean = 19%). Thus, the QoI-resistance conferring G143A mutation was widespread in P. nodorum populations in Virginia and it occurred at a relatively high frequency. Results suggest that fungicides containing QoI active ingredients may not be effective for controlling SNB in Virginia and the surrounding region, and application of stand-alone QoI fungicides for disease control in wheat is not recommended.

Occurrence of quinone outside inhibitor (QoI) resistance in Virginia populations of Parastagonospora nodorum infecting wheat

Plant Disease ◽  
2020 ◽  
Author(s):  
Navjot Kaur ◽  
Chase Mullins ◽  
Nathan Michael Kleczewski ◽  
Hillary Laureen Mehl
Keyword(s):  
Cytochrome B ◽  
Management Practices ◽  
Cultural Practices ◽  
Resistance Management ◽  
Cytochrome B Gene ◽  
Target Site ◽  
Quinone Outside Inhibitor ◽  
Parastagonospora Nodorum ◽  
The U.S ◽  
Qoi Resistance

Stagonospora nodorum blotch (SNB) of wheat, caused by Parastagonospora nodorum, is managed using cultural practices, resistant varieties, and foliar fungicides. Frequent fungicide use can select for fungicide resistance, making certain chemistries less effective; this may in part explain increasing severity of SNB in the mid-Atlantic U.S. Quinone outside inhibitor (QoI) resistance has been documented for a diversity of fungi, but it has not been reported for P. nodorum in the U.S. The objectives of this study were to 1) evaluate QoI sensitivity of P. nodorum from Virginia wheat fields, 2) screen P. nodorum for QoI target site mutations in the cytochrome b gene, and 3) develop a molecular assay to detect target site mutations associated with QoI resistance. Sensitivity of 16 isolates to pyraclostrobin and azoxystrobin was evaluated with radial growth assays, and the cytochrome b gene was sequenced. One isolate was insensitive to both fungicides, and it had the G143A mutation in the cytochrome b gene. For azoxystrobin, 10 isolates without target site mutations had reduced sensitivity. Additional isolates (N=74) were sequenced, and seven had the G143A mutation; all seven isolates with the mutation had reduced sensitivity to pyraclostrobin and azoxystrobin compared to a sensitive control isolate without the mutation. A pyrosequencing assay targeting G143A was developed as a rapid method to screen P. nodorum for the QoI resistance-conferring mutation. To our knowledge, this is the first report of QoI resistant P. nodorum in the U.S. Overall resistance frequency was low, but resistance management practices are needed to maintain the efficacy of fungicides for SNB control.

Cercospora nicotianae Isolates from Flue-Cured Tobacco in North Carolina Found with G143A and F129L Mutations in Cytochrome b Gene

2020 ◽  
Vol 21 (4) ◽  
pp. 288-290
Author(s):  
Andrew Ernst ◽  
Lindsey Thiessen
Keyword(s):  
North Carolina ◽  
Leaf Spot ◽  
Fungicide Resistance ◽  
Single Point ◽  
Leaf Spot Disease ◽  
Single Point Mutation ◽  
Resistance Mutations ◽  
Quinone Outside Inhibitor ◽  
Frogeye Leaf Spot ◽  
Qoi Resistance

Frogeye leaf spot of tobacco caused by Cercospora nicotianae (Ellis & Everhart) is a widespread disease of cultivated tobacco. Recently, flue-cured tobacco producers in North Carolina reported losses due to frogeye leaf spot disease despite the use of strobilurin fungicides. Isolates (n = 4) were obtained in 2018 from affected tobacco leaves from Cumberland, Lenoir, and Nash counties. In 2019, isolates (n = 28) were collected from a field in Wilson county. After sequencing the cytb region of 32 isolates, 30 contained a single point mutation conferring a G143A or F129L amino acid change that resulted in quinone outside inhibitor (QoI) fungicide resistance. Although these resistance mutations have been found in air-cured tobacco in Kentucky, to the best of our knowledge, the present study is the first to report QoI resistance mutations in C. nicotianae populations in flue-cured tobacco and a first report in North Carolina.

scholarly journals A Two-Phase Resistance Response of Venturia inaequalis Populations to the QoI Fungicides Kresoxim-Methyl and Trifloxystrobin

Plant Disease ◽  
2004 ◽  
Vol 88 (5) ◽  
pp. 537-544 ◽  
Author(s):  
Wolfram Köller ◽  
D. M. Parker ◽  
W. W. Turechek ◽  
Cruz Avila-Adame ◽  
Keith Cronshaw
Keyword(s):  
Cytochrome B ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Target Site ◽  
Site Mutation ◽  
Two Phase ◽  
Resistance Response ◽  
Population Responses ◽  
North Germany ◽  
Qoi Resistance

The class of fungicides acting as respiration inhibitors by binding to the Qo center of cyto-chrome b (QoIs) are in wide use for the management of apple scab caused by Venturia inaequalis. In order to assess responses of V. inaequalis populations to treatments with QoIs, sensitivities of isolates were determined for germinating conidia or for mycelial colonies developing from germinating conidia. Under both test conditions, inhibitory potencies of kresoxim-methyl and trifloxystrobin were largely equivalent. V. inaequalis populations treated with QoIs in a commercial and an experimental orchard both responded with significant shifts toward declining QoI sensitivities. However, the population responses were quantitative in nature, and highly resistant isolates indicative of a cytochrome b target site mutation were not detected. V. inaequalis populations from both orchards investigated also were fully resistant to sterol de-methylation-inhibiting fungicides (DMIs) such as fenarimol and myclobutanil, but isolate sensitivities to QoIs and DMIs were largely unrelated. Performance tests with kresoxim-methyl and trifloxystrobin at the experimental orchard diagnosed as DMI-resistant revealed that the quantitative shift toward declining QoI sensitivities did not constitute the status of practical QoI resistance. In contrast to these quantitative responses, emergence of qualitative QoI resistance was documented for V. inaequalis in an orchard in North Germany, which had been treated intensively with a total of 25 QoI applications over four consecutive seasons. Isolates retrieved from the orchard were highly resistant to both kresoxim-methyl and trifloxystrobin and were characterized as G143A cytochrome b mutants. The results indicated that the paths of QoI resistance can be both quantitative and qualitative in nature. A similar phenomenon has not been described before. Circumstantial evidence suggests that the quantitative phase of V. inaequalis population responses to QoIs might be succeeded by a quantitative selection of highly resistant G143A target-site mutants.

scholarly journals Distribution and Stability of Quinone Outside Inhibitor Fungicide Resistance in Populations of Potato Pathogenic Alternaria spp. in Wisconsin

Plant Disease ◽  
2019 ◽  
Vol 103 (8) ◽  
pp. 2033-2040 ◽  
Author(s):  
Shunping Ding ◽  
Dennis A. Halterman ◽  
Kiana Meinholz ◽  
Amanda J. Gevens
Keyword(s):  
Cytochrome B ◽  
Point Mutations ◽  
Alternaria Solani ◽  
Cytochrome B Gene ◽  
Brown Spot ◽  
Qoi Fungicides ◽  
Quinone Outside Inhibitor ◽  
Before And After ◽  
Pathogen Populations ◽  
Qoi Resistance

Quinone outside inhibitor (QoI) fungicides have been an important class in managing potato early blight caused by Alternaria solani and brown spot caused by A. alternata. Because of the single-site mode of action character of QoI fungicides, which are relied on for management of diseases in Wisconsin, and the abundant asexual conidia production of the Alternaria species, pathogen isolates with QoI resistance have been detected after just a few years of QoI fungicide usage in commercial production fields. Resistance to QoIs has been attributed to amino acid substitutions F129L and G143A in cytochrome b of A. solani and A. alternata, respectively, as a result of point mutations. The aim of this study was to assess Alternaria populations in Wisconsin for QoI resistance before and after fungicide applications in order to evaluate resistance stability. A TaqMan single nucleotide polymorphism genotyping assay was designed based on the sequences of the cytochrome b gene from Alternaria isolates collected in Wisconsin to profile QoI resistance in Alternaria populations as well as to explore factors that may influence frequency of QoI resistance in the pathogen populations. This assay successfully identified the mutations conferring QoI resistance in isolates collected from four locations each year from 2015 to 2017. During the course of this study, the frequency of A. solani isolates with the F129L mutation was consistently high and showed primarily the TTA mutation type. The frequency of A. alternata isolates with the G143A mutation started relatively low and increased at the end of the production season in each year (P = 0.0109, P = 0.2083, and P = 0.0159). A potato field managed without use of QoI fungicides showed a significantly lower (P < 0.05) frequency of A. alternata isolates carrying G143A than conventionally managed potato fields. The overall frequency of A. alternata isolates carrying G143A in the four locations was similar over the 3 years (P = 0.2971). The QoI resistance characteristics of the isolates were stable even when QoI selection pressure was removed for at least five subculture transfers, and the mutation types of codons 129 and 143 in the cytochrome b gene in A. solani and A. alternata, respectively, remained the same. This indicated that the application of QoIs in the field is not the sole factor responsible for the variation of the frequency of QoI resistance in the pathogen populations.

scholarly journals Characterization of Quinone Outside Inhibitor Fungicide Resistance in Cercospora sojina and Development of Diagnostic Tools for its Identification

Plant Disease ◽  
2015 ◽  
Vol 99 (4) ◽  
pp. 544-550 ◽  
Author(s):  
F. Zeng ◽  
E. Arnao ◽  
G. Zhang ◽  
G. Olaya ◽  
J. Wullschleger ◽  
...  
Keyword(s):  
Cytochrome B ◽  
Leaf Spot ◽  
Fungicide Resistance ◽  
Cytochrome B Gene ◽  
Diagnostic Tools ◽  
Polymerase Chain Reaction Primer ◽  
Cercospora Sojina ◽  
Qoi Fungicides ◽  
Quinone Outside Inhibitor ◽  
Frogeye Leaf Spot

Frogeye leaf spot of soybean, caused by the fungus Cercospora sojina, reduces soybean yields in most of the top-producing countries around the world. Control strategies for frogeye leaf spot can rely heavily on quinone outside inhibitor (QoI) fungicides. In 2010, QoI fungicide-resistant C. sojina isolates were identified in Tennessee for the first time. As the target of QoI fungicides, the cytochrome b gene present in fungal mitochondria has played a key role in the development of resistance to this fungicide class. The cytochrome b genes from three QoI-sensitive and three QoI-resistant C. sojina isolates were cloned and sequenced. The complete coding sequence of the cytochrome b gene was identified and found to encode 396 amino acids. The QoI-resistant C. sojina isolates contained the G143A mutation in the cytochrome b gene, a guanidine to cytosine transversion at the second position in codon 143 that causes an amino acid substitution of alanine for glycine. C. sojina-specific polymerase chain reaction primer sets and TaqMan probes were developed to efficiently discriminate QoI-resistant and -sensitive isolates. The molecular basis of QoI fungicide resistance in field isolates of C. sojina was identified as the G143A mutation, and specific molecular approaches were developed to discriminate and to track QoI-resistant and -sensitive isolates of C. sojina.

scholarly journals Transcriptomic analysis of insecticide resistance in the lymphatic filariasis vectorCulex quinquefasciatus

2019 ◽  
Author(s):  
Walter Fabricio Silva Martins ◽  
Craig Stephen Wilding ◽  
Alison Taylor Isaacs ◽  
Emily Joy Rippon ◽  
Karine Megy ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Lymphatic Filariasis ◽  
Fold Increase ◽  
Target Site ◽  
Detoxification Enzymes ◽  
Site Mutation ◽  
Public Health Importance ◽  
Metabolic Resistance ◽  
Vector Borne Diseases ◽  
Bendiocarb Resistance

ABSTRACTCulex quinquefasciatusplays an important role in transmission of vector-borne diseases of public health importance, including lymphatic filariasis (LF), as well as many arboviral diseases. Currently, efforts to tackleC. quinquefasciatusvectored diseases are based on either mass drug administration (MDA) for LF, or insecticide-based interventions. Widespread and intensive insecticide usage has resulted in increased resistance in mosquito vectors, includingC. quinquefasciatus. Herein, the transcriptome profile of Ugandan bendiocarb-resistantC. quinquefasciatuswas explored to identify candidate genes associated with insecticide resistance. Resistance to bendiocarb in exposed mosquitoes was marked, with 2.04% mortality following 1h exposure and 58.02% after 4h. Genotyping of the G119SAce-1target site mutation detected a highly significant association (p<0.0001; OR=25) between resistance andAce1-119S. However, synergist assays using the P450 inhibitor PBO or the esterase inhibitor TPP resulted in markedly increased mortality (to ≈80%), suggesting a role of metabolic resistance in the resistance phenotype. Using a novel, custom 60K whole-transcriptome microarray 16 genes significantly overexpressed in resistant mosquitoes were detected, with the P450Cyp6z18showing the highest differential gene expression (>8-fold increase vs unexposed controls). These results provide evidence that bendiocarb-resistance in UgandanC. quinquefasciatusis mediated by both target-site mechanisms and over-expression of detoxification enzymes.

Resistance to Quinone Outside Inhibitor Fungicides Conferred by the G143A Mutation in Cercospora sojina (Causal Agent of Frogeye Leaf Spot) Isolates from Michigan, Minnesota, and Nebraska Soybean Fields

2020 ◽  
Vol 21 (4) ◽  
pp. 230-231 ◽  
Author(s):  
Danilo L. Neves ◽  
Martin I. Chilvers ◽  
Tamra A. Jackson-Ziems ◽  
Dean K. Malvick ◽  
Carl A. Bradley
Keyword(s):  
United States ◽  
Leaf Spot ◽  
Fungicide Resistance ◽  
The United States ◽  
Pcr Assay ◽  
Cercospora Sojina ◽  
Qoi Fungicides ◽  
Quinone Outside Inhibitor ◽  
Frogeye Leaf Spot ◽  
Important Disease

Frogeye leaf spot, caused by Cercospora sojina, is an important disease of soybean (Glycine max) in the United States. An important tactic to manage frogeye leaf spot is to apply foliar fungicides. Isolates of C. sojina were collected from soybean fields in one county in Michigan, three counties in Minnesota, and 10 counties in Nebraska in 2019, and they were tested for resistance to quinone outside inhibitor (QoI) fungicides using a discriminatory dose assay, a PCR assay, and DNA sequencing. Results of the testing indicated that QoI fungicide-resistant isolates were detected in isolates from all counties. Testing results also indicated that the G143A mutation was responsible for the QoI fungicide resistance. This is the first report of QoI fungicide-resistant C. sojina isolates in Michigan, Minnesota, and Nebraska and expands the geographical distribution of QoI fungicide-resistant C. sojina isolates to 18 states in total.

scholarly journals Strobilurin (QoI) Resistance in Populations of Erysiphe necator on Grapes in Michigan

Plant Disease ◽  
2012 ◽  
Vol 96 (11) ◽  
pp. 1621-1628 ◽  
Author(s):  
L. A. Miles ◽  
T. D. Miles ◽  
W. W. Kirk ◽  
A. M. C. Schilder
Keyword(s):  
Powdery Mildew ◽  
Fungicide Resistance ◽  
Resistance Management ◽  
The United States ◽  
Suboptimal Control ◽  
Single Nucleotide ◽  
Erysiphe Necator ◽  
Nucleotide Mutation ◽  
Conidium Germination ◽  
Qoi Resistance

Powdery mildew, caused by Erysiphe necator, is the most common and destructive disease of grapes (Vitis spp.) worldwide. In Michigan, it is primarily controlled with fungicides, including strobilurins (quinone outside inhibitors [QoIs]). Within the United States, resistance to this class of fungicides has been reported in E. necator populations in some east coast states. Among 12 E. necator isolates collected from five Michigan vineyards in 2008, one carried the G143A single-nucleotide mutation responsible for QoI resistance. This isolate was confirmed to be resistant in a conidium germination assay on water agar amended with trifloxystrobin at 0.001, 0.01, 0.1, 1, 10, or 100 μg/ml and salicylhydroxamic acid (100 mg/liter). The mutant isolate was able to germinate on media amended with 100 μg/ml trifloxystrobin, whereas a representative wild-type isolate did not germinate at concentrations higher than 0.1 μg/ml. In 2009, 172 isolates were collected from a total of 21 vineyards (juice and wine grapes): three vineyards with no fungicide application history (baseline sites), six research vineyards, and 12 commercial vineyards. QoI resistance was defined as the effective concentration that inhibited 50% of conidial germination (EC50) > 1 μg/ml. Isolates from baseline sites had EC50 values mostly below 0.01 μg/ml, while isolates that were highly resistant to trifloxystrobin (EC50 > 100 μg/ml) occurred in five research and three commercial wine grape vineyards at frequencies of 40 to 100% and 25 to 75% of the isolates, respectively. The G143A mutation was detected in every isolate with an EC50 > 1 μg/ml. These results suggest that fungicide resistance may play a role in suboptimal control of powdery mildew observed in some Michigan vineyards and emphasizes the need for continued fungicide resistance management.

Sign in / Sign up

Export Citation Format

Share Document