scholarly journals Characterization of Monilinia fructicola Strains Resistant to Both Propiconazole and Boscalid

Plant Disease ◽  
2013 ◽  
Vol 97 (5) ◽  
pp. 645-651 ◽  
Author(s):  
F. Chen ◽  
X. Liu ◽  
S. Chen ◽  
E. Schnabel ◽  
G. Schnabel
Keyword(s):  
Succinate Dehydrogenase ◽  
Disease Incidence ◽  
Mobile Element ◽  
Brown Rot ◽  
Monilinia Fructicola ◽  
Quinone Outside Inhibitor ◽  
Dehydrogenase Enzyme ◽  
Rot Disease ◽  
Succinate Dehydrogenase Inhibitor ◽  
Spartanburg County

In 2011 and 2012, significant brown rot disease caused by Monilinia fructicola was observed in a peach orchard in Spartanburg County, SC, despite preharvest fungicide applications of demethylation inhibitor (DMI), quinone outside inhibitor (QoI), and succinate dehydrogenase inhibitor (SDHI) fungicides. All 22 isolates obtained in 2011 from this orchard were sensitive to the QoI fungicide, azoxystrobin, and the methyl benzimidazole carbamate (MBC) fungicide, thiophanate-methyl. Five were resistant to the DMI fungicide, propiconazole, and were selected, together with five propiconazole-sensitive isolates, for further investigations. One of the 10 isolates was resistant to propiconazole but sensitive to the SDHI fungicide, boscalid (EC50 = 0.42 μg/ml), 3 were resistant to propiconazole with intermediate sensitivity to boscalid (EC50 0.72 to 2.1 μg/ml); 2 were sensitive to propiconazole with intermediate sensitivity to boscalid; 3 were sensitive to propiconazole but resistant to boscalid (EC50 ≥ 2.1 μg/ml); and 1 (isolate MD22) was resistant to both propiconazole and boscalid. Disease incidence on detached fruit treated with formulated propiconazole or boscalid was significantly higher for MD22 compared to a sensitive control isolate. Continued monitoring of fungicide resistance in the same orchard in 2012 revealed an increase of isolates resistant to propiconazole from 22.7% in 2011 to 34.7%, and an increase of isolates resistant to both propiconazole and boscalid from 4.5% in 2011 to 18.4%. Propiconazole resistance was always associated with the presence of the ‘Mona’ mobile element located upstream of the sterol 14α-demethylase (MfCYP51) gene. To investigate whether mutations in the subunits of the succinate dehydrogenase enzyme were involved in boscalid resistance, significant portions of the M. fructicola SdhA, SdhB, SdhC, and SdhD genes were cloned and analyzed for 2 sensitive, 2 boscalid-resistant, and 6 dual-resistant isolates. Although sequence variation was found among the isolates, no single change correlated with resistance. Interestingly, analysis of isolates collected from orchards in 2001 and 2002, prior to the registration of boscalid, revealed a range of sensitivities to boscalid (EC50 0.03 to 3.46 μg/ml) including boscalid-resistant isolates. The presence of boscalid-resistant isolates in the baseline population was unexpected and requires further investigation.

scholarly journals Reduced Sensitivity in Monilinia fructicola to Propiconazole in Georgia and Implications for Disease Management

Plant Disease ◽  
2004 ◽  
Vol 88 (9) ◽  
pp. 1000-1004 ◽  
Author(s):  
Guido Schnabel ◽  
P. Karen Bryson ◽  
William C. Bridges ◽  
Phillip M. Brannen
Keyword(s):  
South Carolina ◽  
Disease Incidence ◽  
Brown Rot ◽  
Field Testing ◽  
Monilinia Fructicola ◽  
Single Spore ◽  
Peach Fruit ◽  
Dmi Fungicides ◽  
Agar Media ◽  
Population Sensitivity

Single-spore isolates of Monilinia fructicola were collected from commercial orchards in South Carolina and Georgia with prolonged past exposure to demethylation inhibitor (DMI) fungicides and from an orchard with no DMI history (baseline population). Sensitivity to propiconazole was determined using the concentration in agar media required to suppress radial growth of mycelium by 50% (EC50. Mean EC50 values from six South Carolina populations were not different from the baseline population (P < 0.05). Two of five populations from Georgia revealed (significantly higher mean EC50 values compared with the baseline population (P < 0.05). Isolates with high (AP5 and AP6) and low (DL71 and DL72) EC50 values were selected to determine disease incidence on peach fruit after protective or curative applications of propiconazole at 0.15 or 0.3 liter/ha (half and full label rate, respectively). Disease incidence was significantly greater on peaches inoculated with AP5 and AP6 after curative treatment with propiconazole at 0.15 liter/ha (P < 0.05). Following protective or curative treatments at 0.3 liter/ha, disease incidence was significantly greater for AP6 but not for AP5. These results suggest that a shift toward reduced sensitivity has developed in some M. fructicola populations from Georgia, and that isolates with reduced sensitivity to propiconazole are more difficult to control in the field. Field testing of DMI fungicides, captan, QoI fungicides, and fenhexamid in experimental orchards) indicated that the DMI fungicides are still among the most efficacious products for brown rot (control, and that new products containing QoI fungicides may be viable disease control alternatives or rotation partners.

Cloning and differential expression of a plum single repeat-MYB, PdMYB3, in compatible and incompatible interactions during fungal infection

2013 ◽  
Vol 93 (4) ◽  
pp. 599-605 ◽  
Author(s):  
Ashraf El-kereamy ◽  
Subramanian Jayasankar
Keyword(s):  
Fungal Infection ◽  
Differential Expression ◽  
Potential Role ◽  
Brown Rot ◽  
Myb Transcription Factor ◽  
Economic Damage ◽  
Monilinia Fructicola ◽  
Resistant Varieties ◽  
Rot Disease ◽  
Incompatible Interactions

El-kereamy, A. and Jayasankar, S. 2013. Cloning and differential expression of a plum single repeat-MYB, PdMYB3, in compatible and incompatible interactions during fungal infection. Can. J. Plant Sci. 93: 599–605. Enhancing resistance to pathogen attack through conventional breeding is a major challenge, especially in perennial species. Monilinia fructicola fungal infection causes brown rot disease, resulting in economic damage of stone fruits at flowering, pre- and post-harvest stages. The molecular mechanism of resistance to this disease is still not known. In the present study, we cloned and analyzed the expression of a novel MYB transcription factor from European plums (PdMYB3) induced in response to M. fructicola fungal infection. The identified PdMYB3 is a single repeat-MYB protein that contains a conserved SHAQKYF motif. Monilinia fructicola infection induces the expression of PdMYB3 in fruits of four cultivars within 24 h; however, it is differentially expressed in the susceptible and resistant varieties. By comparing four different cultivars we found that PdMYB3 is induced in much higher levels in the susceptible cultivars than the resistant ones. In addition the PdMYB3 expression is higher in the early stages of fruit development prior to pit hardening, suggesting a potential role for PdMYB3 during this stage. Promoter analysis revealed the presence of some hormone cis-elements suggesting a possible role for PdMYB3 gene in transmitting a signal from the hormonal pathways to downstream components during host-pathogen interactions.

scholarly journals Comparative analysis of Monilinia fructicola and M. laxa isolates from Brazil: monocyclic components of peach brown rot

2017 ◽  
Vol 47 (6) ◽  
Author(s):  
Sthela Siqueira Angeli ◽  
Louise Larissa May De Mio ◽  
Lilian Amorim
Keyword(s):  
Disease Incidence ◽  
Beta Function ◽  
Brown Rot ◽  
Maximum Temperature ◽  
Monilinia Fructicola ◽  
Peach Fruit ◽  
Conidia Germination ◽  
Production Area ◽  
Important Disease

ABSTRACT: Brown rot is the most important disease of peaches in Brazil. The objective of this study was to compare the brown rot monocyclic components from Monilinia fructicola and M. laxa isolates from Brazil on peaches, due to the detection of M. laxa in the São Paulo production area. Conidia germination and pathogen sporulation were assessed in vitro under a temperature range of 5-35oC and wetness duration of 6-48h. Incubation and latent periods, disease incidence, disease severity and pathogen reproduction on peach fruit were evaluated under 10, 15, 20, 25 and 30oC and wetness duration of 6, 12 and 24h. Six of seven parameters of a generalised beta function fitted to conidia germination of M. fructicola and M. laxa were similar. Only the shape parameter was higher for M. fructicola indicating that the range of temperatures and wetness periods favourable for germination is wider for M. laxa than for M. fructicola. The optimum temperature for brown rot development caused by M. fructicola was 24.5oC and for. Monilinia laxa was 19.8oC. At 10oC M. laxa lesions produced more conidia than M. fructicola, and the opposite occurred at 30oC. The estimated maximum temperature for lesion development was also higher for M. fructicola than for M. laxa. M. fructicola is favored by warmer weather than M. laxa and the presence and impact of this specie in Brazil must be investigated especially in the South states.

scholarly journals Reduced Sensitivity to Azoxystrobin of Monilinia fructicola Isolates From Brazilian Stone Fruits is Not Associated With Previously Described Mutations in the Cytochrome b Gene

Plant Disease ◽  
2017 ◽  
Vol 101 (5) ◽  
pp. 766-773 ◽  
Author(s):  
Wagner V. Pereira ◽  
Isabela V. Primiano ◽  
Rafael G. F. Morales ◽  
Natalia A. Peres ◽  
Lilian Amorim ◽  
...  
Keyword(s):  
Cytochrome B ◽  
Ex Vivo ◽  
Brown Rot ◽  
Monilinia Fructicola ◽  
Cyt B ◽  
Qoi Fungicides ◽  
Quinone Outside Inhibitor ◽  
Low Sensitivity ◽  
Cyt B Gene

Quinone-outside inhibitor (QoI) fungicides are effective tools for preharvest control of brown rot of stone fruit. These fungicides have a very specific site of action so the risk of resistance selection is high. The sensitivity of Monilinia fructicola (G. Winter) Honey isolates to azoxystrobin (QoI) was investigated in 143 isolates collected between 2002 and 2011 from four Brazilian states in orchards with different frequencies of fungicide use (0 to 6 fungicides sprays/season). Sensitivity of the isolates to azoxystrobin was determined in vitro, by inhibition of mycelial growth and spore germination on fungicide-amended media or ex vivo by pathogen inoculation in untreated or treated fruit with azoxystrobin. Potential mutations in codons 143, 137, and 129 of the cytochrome b (Cyt b) gene and the occurrence of an intron immediately after codon 143 were analyzed in a subpopulation of the isolates. The M. fructicola population of São Paulo State was less sensitive to the fungicide than the population from the states of Paraná, Santa Catarina, and Rio Grande do Sul. The low sensitivity of the isolates was confirmed also by comparing to the sensitivity of the baseline isolates. Mutations in G143A, F129L, and G137R in Cyt b gene were not found. In addition, 58 isolates tested showed an intron after codon 143 in Cyt b gene. Our results indicate that other mechanisms of selection for low sensitivity to QoI fungicides should be investigated.

scholarly journals Mating System in the Brown Rot Pathogens Monilinia fructicola, M. laxa, and M. fructigena

2018 ◽  
Vol 108 (11) ◽  
pp. 1315-1325 ◽  
Author(s):  
Domenico Abate ◽  
Rita M. De Miccolis Angelini ◽  
Caterina Rotolo ◽  
Stefania Pollastro ◽  
Francesco Faretra
Keyword(s):  
Mating System ◽  
Population Biology ◽  
Constitutive Expression ◽  
Brown Rot ◽  
Antisense Transcription ◽  
Inter Simple Sequence Repeat ◽  
Monilinia Fructicola ◽  
Specific Pcr ◽  
Rot Disease ◽  
Flanking Regions

Monilinia fructicola, M. laxa, and M. fructigena are the most important pathogens responsible for brown rot disease of stone and pome fruits. Information on their mating system and sexual behavior is scant. A mating-type-specific PCR-based assay was developed and applied to 155 Monilinia isolates from 10 countries and 10 different host plants. We showed that single isolates carry only one of two opposite idiomorphs at the MAT1 locus consistent with a heterothallic mating system for all three species. MAT1-1 and MAT1-2 mating types were detected in similar proportions in samples of isolates of each species and hence there do not appear to be genetic obstacles to the occurrence of sexual reproduction in their populations. Inter simple sequence repeat markers suggested that asexual reproduction is prevalent, but that sexual recombination occurs in M. fructicola populations in Italy. The genetic architectures of the MAT1 loci of the three pathogens were analyzed. MAT1-1 and MAT1-2 idiomorphs are flanked upstream and downstream by the APN2 and SLA2 genes and resemble those of Botrytis cinerea and other heterothallic fungi in the family Sclerotiniaceae. Each idiomorph contains a specific couple of genes, MAT1-1-1 (with alpha-box domain) and MAT1-1-5 in MAT1-1, and MAT1-2-1 (with HMG-box domain) and MAT1-2-10 in MAT1-2. Small gene fragments (dMAT1-1-1 and dMAT1-2-1) from the opposite idiomorph were detected close to their flanking regions. Constitutive expression of the four MAT1 genes during vegetative growth was ascertained by transcriptomic analysis (RNA-Seq). Antisense transcription of the MAT1-1-1 and MAT1-2-1 genes and intergenic transcribed regions of the MAT1 locus were detected. These results represent new insights into the mating systems of these three economically-important pathogens which could contribute to improve the knowledge on their population biology.

scholarly journals Draft Genome Resources for the Phytopathogenic Fungi Monilinia fructicola, M. fructigena, M. polystroma, and M. laxa, the Causal Agents of Brown Rot

2018 ◽  
Vol 108 (10) ◽  
pp. 1141-1142 ◽  
Author(s):  
Yazmín Rivera ◽  
Kurt Zeller ◽  
Subodh Srivastava ◽  
Jeremy Sutherland ◽  
Marco Galvez ◽  
...  
Keyword(s):  
Draft Genome ◽  
Brown Rot ◽  
Phytopathogenic Fungi ◽  
Monilinia Fructicola ◽  
Pome Fruits ◽  
Rot Disease ◽  
Genome Assemblies

Fungi in the genus Monilinia cause brown rot disease of stone and pome fruits. Here, we report the draft genome assemblies of four important phytopathogenic species: M. fructicola, M. fructigena, M. polystroma, and M. laxa. The draft genome assemblies were 39 Mb (M. fructigena), 42 Mb (M. laxa), 43 Mb (M. fructicola), and 45 Mb (M. polystroma) with as few as 550 contigs (M. laxa). These are the first draft genome resources publicly available for M. laxa, M. fructigena, and M. polystroma.

scholarly journals Reduced Sensitivity in Monilinia fructicola Field Isolates from South Carolina and Georgia to Respiration Inhibitor Fungicides

Plant Disease ◽  
2010 ◽  
Vol 94 (6) ◽  
pp. 737-743 ◽  
Author(s):  
A. Amiri ◽  
P. M. Brannen ◽  
G. Schnabel
Keyword(s):  
South Carolina ◽  
Mycelial Growth ◽  
Disease Incidence ◽  
Brown Rot ◽  
Conidial Germination ◽  
Cross Resistance ◽  
Monilinia Fructicola ◽  
Significant Difference

Quinone outside inhibitor (QoI) and succinate dehydrogenase inhibitor (SdhI) fungicides are respiration inhibitors (RIs) used for preharvest control of brown rot of stone fruit. Both chemical classes are site-specific and, thus, prone to resistance development. Between 2006 and 2008, 157 isolates of Monilinia fructicola collected from multiple peach and nectarine orchards with or without RI spray history in South Carolina and Georgia were characterized based upon conidial germination and mycelial growth inhibition for their sensitivity to QoI fungicides azoxystrobin and pyraclostrobin, SdhI fungicide boscalid, and a mixture of pyraclostrobin + boscalid. There was no significant difference (P = 0.05) between EC50 values for inhibition of conidial germination versus mycelial growth. The mean EC50 values based upon mycelial growth tests for 25 isolates from an orchard without RI-spray history were 0.15, 0.06, 2.23, and 0.09 μg/ml for azoxystrobin, pyraclostrobin, boscalid, and pyraclostrobin + boscalid, respectively. The respective mean EC50 values for 76 isolates from RI-sprayed orchards in South Carolina were 0.9, 0.1, 10.7, and 0.13 μg/ml and for 56 isolates from RI-sprayed orchards in Georgia were 1.2, 0.1, 8.91, and 0.17 μg/ml. Overall, mean EC50 values of populations from RI-sprayed orchards increased three-, two-, five-, and twofold between 2006 and 2008 for azoxystrobin, pyraclostrobin, boscalid, and pyraclostrobin + boscalid, respectively. A subset of 10 M. fructicola isolates representing low and high EC50 values for azoxystrobin, boscalid, and boscalid + pyraclostrobin was selected for a detached fruit assay to determine disease incidence and severity following protective treatments of formulated RI fungicides at label rates. Brown rot incidence was greater than 50% when fruit were inoculated with isolates having EC50 values of 2, 4, and 0.6 μg/ml for azoxystrobin, boscalid, and pyraclostrobin + boscalid, respectively. Pyraclostrobin failed to control any of the isolates tested in detached fruit assays. Based on minimum inhibitory concentration and brown rot incidence data, we recommend using 3 and 0.75 μg/ml as discriminatory doses to distinguish between sensitive isolates and those with reduced sensitivity to azoxystrobin and pyraclostrobin + boscalid, respectively. Results from our in vitro and in vivo assays indicate a shift toward reduced sensitivity in M. fructicola from the southeastern United States. No cross-resistance was observed between the QoI and the SdhI fungicides, which implies that rotation or tank mixtures of these two chemical classes can be used as a resistance management strategy.

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