scholarly journals Redox Climate in Quiescence and Pathogenicity of Postharvest Fungal Pathogens

2003 ◽  
Author(s):  
Richard M. Bostock ◽  
Dov Prusky ◽  
Martin Dickman
Keyword(s):  
Redox Potential ◽  
Fungal Pathogens ◽  
High Efficiency ◽  
Fluorescent Protein ◽  
Brown Rot ◽  
Hyphal Growth ◽  
Fruit Rot ◽  
Putative Virulence Factor ◽  
Immature Fruit ◽  
Related Compounds

Monilinia fructicola causes brown rot blossom blight and fruit rot in stone fruits. Immature fruit are highly resistant to brown rot but can become infected. These infections typically remain superficial and quiescent until they become active upon maturation of the fruit. High levels of chlorogenic acid (CGA) and related compounds occur in the peel of immature fruit but these levels decline during ripening. CGA inhibits cutinase expression, a putative virulence factor, with little or no effect on spore germination or hyphal growth. To better understand the regulation of cutinase expression by fruit phenolics, we examined the effect of CGA, caffeic acid (CA) and related compounds on the redox potential of the growth medium and intracellular glutathione (GSH) levels. The presence of CA in the medium initially lowered the electrochemical redox potential of the medium, increased GSH levels and inhibited cutinase expression. Conidia germinated in the presence of CA, CGA, or GSH produced fewer appressoria and had elongated germ tubes compared to the controls. These results suggest that host redox compounds can regulate fungal infectivity.   In order to genetically manipulate this fungus, a transformation system using Agrobacterium was developed. The binary transformation vector, pPTGFPH, was constructed from the plasmid pCT74, carrying green fluorescent protein (GFP) driven by the ToxA promoter of Pyrenophora tritici-repentis and hygromycin B phosphotransferase (hph) under control of the trpC promoter of from Aspergillus nidulans, and the binary vector pCB403.2, carrying neomycin phosphotransferase (nptII) between the T-DNA borders. Macroconidia of M. fructicola were coincubated with A. tumefaciens strain LBA 4404(pPTGFPH) on media containing acetosyringone for two days. Hygromycin- and G418-resistant M. fructicola transformants were selected while inhibiting A. tumefaciens with cefotaxime. Transformants expressing GFP fluoresced brightly, and were formed with high efficiency and frequency of T-DNA integration frequency. The use of these transformants for in situ studies on stone fruit tissues is discussed.

scholarly journals N-acetylcysteine inhibits germination of conidia and growth of Aspergillus spp. and Fusarium spp.

1996 ◽  
Vol 40 (5) ◽  
pp. 1274-1276 ◽  
Author(s):  
A J De Lucca ◽  
T J Walsh ◽  
D J Daigle
Keyword(s):  
Fungal Pathogens ◽  
Therapeutic Strategy ◽  
Hyphal Growth ◽  
Conidial Germination ◽  
Fusarium Spp ◽  
Related Compounds ◽  
Better Than

N-Acetylcysteine inhibited hyphal growth and germination of conidia of Aspergillus spp. and Fusarium spp. N-Acetylcysteine inhibited conidial germination as well as or better than L-cysteine. Cysteine-related compounds may provide a potential therapeutic strategy against agriculturally and medically important fungal pathogens.

scholarly journals First Report of Brown Rot of Stone Fruit Caused by Monilinia fructicola in Italy

Plant Disease ◽  
2009 ◽  
Vol 93 (6) ◽  
pp. 668-668 ◽  
Author(s):  
C. Pellegrino ◽  
M. L. Gullino ◽  
A. Garibaldi ◽  
D. Spadaro
Keyword(s):  
Fungal Pathogens ◽  
Brown Rot ◽  
Stone Fruit ◽  
Fruit Rot ◽  
Brown Spot ◽  
Morphological Identification ◽  
Monilinia Fructicola ◽  
Stone Fruits ◽  
First Report ◽  
Sequence Characterized Amplified Region

Monilinia fructicola, causal agent of brown rot, is one of the most important fungal pathogens of stone fruit. M. fructicola is a quarantined pathogen in Europe. During the summer of 2008 in 15 orchards located in Piedmont (northern Italy), 12,500 stone fruits (cherries, apricots, peaches, nectarines, and plums) were stored in cold chambers at 4 and 6°C and monitored for 8 weeks for the presence of Monilinia spp. M. fructicola was detected on 0.5% of nectarines (cvs. Sweet Red and Orion) that originated from two orchards in Lagnasco. Symptoms appeared on the fruit during storage, starting 3 weeks after harvest. Fruit rot lesions were brown, sunken, and covered with grayish tufts. The majority of infected fruit became dry and mummified. Brown rot symptoms were similar to those caused by endemic M. fructigena and M. laxa. Symptoms began with a small, circular, brown spot, and the rot spread rapidly. At the same time, numerous, small, grayish stromata developed. Finally, the whole surface of the fruit was covered by conidial tufts. Tissues were excised from diseased stone fruits and cultured on potato dextrose agar (PDA) amended with 25 μg of streptomycin per liter. The isolates produced abundant mycelium on PDA at 20 ± 2°C. Colonies were initially gray, but after sporulation, they became hazel, showing concentric rings (sporulation is sparse in M. laxa or M. fructigena). Conidia were one-celled, ellipsoid, hyaline, 15.2 × 10.1 μm, and produced in branched monilioid chains (2). Preliminary morphological identification of fungi resembling M. fructicola was confirmed by PCR using genomic DNA extracted from the mycelia of pure cultures. The DNA was amplified with a common reverse primer and three species-specific forward primers (3) obtained from a sequence characterized amplified region and a product of 535 bp, diagnostic for the species M. fructicola, was obtained. BLAST analysis of the amplified sequence (GenBank Accession No. FI569728) showed 96% similarity to the sequence of a M. fructicola isolated from Canada (GenBank Accession No. AF506700), 15% similarity to M. laxa ATCC11790 (GenBank Accession No. AF506702), and 35% similarity to a M. fructigena sequence isolated in Italy (GenBank Accession No. AF506701). Moreover, two sequences obtained through the amplification of ribosomal region ITS1-5.8S-ITS2, showing 100% similarity to the same ribosomal sequence of M. fructicola, were deposited in GenBank (Accession Nos. FJ411109 and FJ411110). The pathogen was detected on some mummified fruit from the same orchards in November of 2008. Pathogenicity was tested by spraying 103 conidia/ml on 10 surface-sterilized artificially wounded nectarines per strain of M. fructicola. After 5 days of incubation at 20 ± 2°C, typical, brown, rot symptoms developed on inoculated fruit. M. fructicola was reisolated from the inoculated fruit on PDA. Symptoms did not appear on control fruit. To our knowledge, this is the first report of M. fructicola in Italy. Its occurrence in Europe has been reported sporadically in Austria and France, and in 2006, it was detected in Hungary and Switzerland on peaches and nectarines imported from Italy and Spain (1,4). References: (1) E. Bosshard et al. Plant Dis. 90:1554, 2006. (2) R. J. W. Byrde and H. J. Willetts. The Brown Rot Fungi of Fruit: Their Biology and Control. Pergamon Press, Oxford, 1977. (3) M. J. Coté et al. Plant Dis. 88:1219, 2004. (4) M. Petròczy and L. Palkovics. Plant Dis. 90:375, 2006.

scholarly journals Incidence of Latent Infection of Immature Peach Fruit by Monilinia fructicola and Relationship to Brown Rot in Georgia

Plant Disease ◽  
2000 ◽  
Vol 84 (8) ◽  
pp. 853-857 ◽  
Author(s):  
K. M. Emery ◽  
T. J. Michailides ◽  
H. Scherm
Keyword(s):  
Latent Infection ◽  
Disease Risk ◽  
Brown Rot ◽  
Biological Indicator ◽  
Fruit Rot ◽  
Monilinia Fructicola ◽  
Latent Infections ◽  
Ripening Stage ◽  
Peach Fruit ◽  
Immature Fruit

Peach fruit are most susceptible to infection by Monilinia fructicola during the preharvest ripening stage. Although various sources of inoculum for preharvest infection have been characterized, the role of latent infection of immature fruit in the carryover of M. fructicola from the spring (blossom blight phase) to the preharvest period (fruit rot phase) is unknown for the southeastern United States. From 1997 to 1999, immature peach fruit were collected at 14-day intervals from orchards in middle and northern Georgia. Fruit were surface disinfested and treated with paraquat (1997) or frozen overnight (1998 and 1999) to induce tissue senescence and activate latent infections. Across sites and years, the incidence of latent infection remained low until the final sampling date 7 to 12 days before harvest. The incidence of latent infection on the final sampling date ranged from 0 to 22.0% and correlated significantly with both the incidence of blossom blight earlier in the season (r = 0.9077, P = 0.0332) and the incidence of fruit rot at harvest (r = 0.9966, P = 0.0034). There also was a significant association between the incidence of latent infection at the onset of pit hardening (between 7 and 10 weeks before harvest) and subsequent fruit rot incidence (r = 0.9763, P = 0.0237). Weather variables (cumulative rainfall or rainfall frequency) alone did not correlate with fruit rot incidence (P > 0.05), whereas combined latent infection-rainfall variables did. The results suggest that latent infections can serve as a source of inoculum for subsequent fruit rot in peach orchards in Georgia. Despite its significant association with fruit rot incidence, the potential for using latent infection incidence as a biological indicator of disease risk at harvest may be limited; the assessment of latent infection during the fruit ripening stage (similar to the timing of the final sampling date in this study) would not provide sufficient lead time for preharvest disease management decisions, whereas an earlier assessment (e.g., at the onset of pit hardening) would require large sample sizes due to the low incidence of latent infection present during that period.

scholarly journals First Report of Fruit Rot on Plum Caused by Monilinia fructicola at Alcalá del Río (Seville), Southwestern Spain

Plant Disease ◽  
2012 ◽  
Vol 96 (4) ◽  
pp. 590-590 ◽  
Author(s):  
F. T. Arroyo ◽  
M. Camacho ◽  
A. Daza
Keyword(s):  
Fungal Pathogens ◽  
Brown Rot ◽  
Fruit Rot ◽  
Morphological Data ◽  
Monilinia Fructicola ◽  
First Report ◽  
Sequence Characterized Amplified Region ◽  
Agar Plug ◽  
Pure Cultures ◽  
Del Rio

Monilinia fructicola, causal agent of brown rot, is one of the most important fungal pathogens of stone fruit. In the summer of 2011, Japanese plum fruit of ‘Larry Ann’ (Prunus salicina Lindl) showing symptoms of fruit rot disease were detected and collected from trees in an experimental field at Alcalá del Río (Seville), southwestern Spain. Fruit rot lesions were brown, sunken, and covered with grayish brown tufts or pustules. The majority of infected fruit became dry and mummified on the trees after 30 days. Symptoms were similar to those caused by three Monilinia species, M. laxa, M. fructigena, and M. fructicola (2). Pieces of infected tissue, previously disinfested in 0.6% NaOCl, were placed on potato dextrose agar (PDA) amended with 50 μg of streptomycin per liter and incubated at 22°C with a 12-h photoperiod for 15 days. The isolates produced abundant, grayish white mycelium, which after sporulation became hazel in color, and colonies displayed concentric rings. Colonies produced scarce conidia, which were arranged in branched, monilioid chains. Conidia were one celled, hyaline, ellipsoid to lemon shaped, and measured 15.42 ± 1.91 × 8.02 ± 0.9 μm. The morphological data and growth rates match the description of M. fructicola (Winter) Honey (2–4). Fungal identification was confirmed by PCR using genomic DNA extracted from the mycelia of pure cultures. The DNA was amplified with a common reverse primer and three specific forward primers obtained from a sequence-characterized, amplified region that distinguishes between M. fructicola, M. fructigena, and M. laxa. The size of the amplified fragment (a product of 535 bp) fit with the one described for M. fructicola (2). To confirm the pathogenicity of the isolate, mature ‘Larry Ann’ and ‘Sungold’ plum fruits (six fruits per cultivar) were inoculated by placing an agar plug from the edge of an actively growing colony on PDA directly on the fruit surface. After 5 days of incubation, typical brown rot symptoms developed on inoculated fruit and the fungus was successfully reisolated, thus fulfilling Koch's postulates. No symptoms appeared on control fruit. To our knowledge, this is the first report of M. fructicola on plums in southwestern Spain. M. fructicola is a quarantined pathogen in Europe and has been reported on imported apricot and nectarine (1) and peach in several European countries (3,4). References: (1) E. Bosshard et al. Plant Dis. 90:1554, 2006. (2) M. J. Côté. Plant Dis. 88:1219, 2004. (3) A. De Cal and I. Gell. Plant Dis. 93:763, 2009. (4). C. Pellegrino et al. Plant Dis. 93:668, 2009.

scholarly journals A Ras-like GTPase Is Involved in Hyphal Growth Guidance in the Filamentous Fungus Ashbya gossypii

2004 ◽  
Vol 15 (10) ◽  
pp. 4622-4632 ◽  
Author(s):  
Yasmina Bauer ◽  
Philipp Knechtle ◽  
Jürgen Wendland ◽  
Hanspeter Helfer ◽  
Peter Philippsen
Keyword(s):  
Fluorescent Protein ◽  
Hyphal Growth ◽  
Time Lapse ◽  
Growth Direction ◽  
Ashbya Gossypii ◽  
Growth Guidance ◽  
Characteristic Features ◽  
Green Fluorescent ◽  
Hyphal Tip

Characteristic features of morphogenesis in filamentous fungi are sustained polar growth at tips of hyphae and frequent initiation of novel growth sites (branches) along the extending hyphae. We have begun to study regulation of this process on the molecular level by using the model fungus Ashbya gossypii. We found that the A. gossypii Ras-like GTPase Rsr1p/Bud1p localizes to the tip region and that it is involved in apical polarization of the actin cytoskeleton, a determinant of growth direction. In the absence of RSR1/BUD1, hyphal growth was severely slowed down due to frequent phases of pausing of growth at the hyphal tip. During pausing events a hyphal tip marker, encoded by the polarisome component AgSPA2, disappeared from the tip as was shown by in vivo time-lapse fluorescence microscopy of green fluorescent protein-labeled AgSpa2p. Reoccurrence of AgSpa2p was required for the resumption of hyphal growth. In the Agrsr1/bud1Δ deletion mutant, resumption of growth occurred at the hyphal tip in a frequently uncoordinated manner to the previous axis of polarity. Additionally, hyphal filaments in the mutant developed aberrant branching sites by mislocalizing AgSpa2p thus distorting hyphal morphology. These results define AgRsr1p/Bud1p as a key regulator of hyphal growth guidance.

scholarly journals Novel Chemical Class of pUL97 Protein Kinase-Specific Inhibitors with Strong Anticytomegaloviral Activity

2004 ◽  
Vol 48 (11) ◽  
pp. 4154-4162 ◽  
Author(s):  
Thomas Herget ◽  
Martina Freitag ◽  
Monika Morbitzer ◽  
Regina Kupfer ◽  
Thomas Stamminger ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Kinase Activity ◽  
Kinase Inhibitors ◽  
High Efficiency ◽  
Fluorescent Protein ◽  
Human Fibroblasts ◽  
Growth Factor Receptor ◽  
Protein Kinase Activity ◽  
Hcmv Replication

ABSTRACT Human cytomegalovirus (HCMV) is a major human pathogen frequently associated with life-threatening disease in immunosuppressed patients and newborns. The HCMV UL97-encoded protein kinase (pUL97) represents an important determinant of viral replication. Recent studies demonstrated that pUL97-specific kinase inhibitors are powerful tools for the control of HCMV replication. We present evidence that three related quinazoline compounds are potent inhibitors of the pUL97 kinase activity and block in vitro substrate phosphorylation, with 50% inhibitory concentrations (IC50s) between 30 and 170 nM. Replication of HCMV in primary human fibroblasts was suppressed with a high efficiency. The IC50s of these three quinazoline compounds (2.4 ± 0.4, 3.4 ± 0.6, and 3.9 ± 1.1 μM, respectively) were in the range of the IC50 of ganciclovir (1.2 ± 0.2 μM), as determined by the HCMV green fluorescent protein-based antiviral assay. Importantly, the quinazolines were demonstrated to have strong inhibitory effects against clinical HCMV isolates, including ganciclovir- and cidofovir-resistant virus variants. Moreover, in contrast to ganciclovir, the formation of resistance to the quinazolines was not observed. The mechanisms of action of these compounds were confirmed by kinetic analyses with infected cells. Quinazolines specifically inhibited viral early-late protein synthesis but had no effects at other stages of the replication cycle, such as viral entry, consistent with a blockage of the pUL97 function. In contrast to epithelial growth factor receptor inhibitors, quinazolines affected HCMV replication even when they were added hours after virus adsorption. Thus, our findings indicate that quinazolines are highly efficient inhibitors of HCMV replication in vitro by targeting pUL97 protein kinase activity.

scholarly journals Peach Brown Rot: Still in Search of an Ideal Management Option

Agriculture ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 125 ◽  
Author(s):  
Vitus Ikechukwu Obi ◽  
Juan José Barriuso ◽  
Yolanda Gogorcena
Keyword(s):  
Fungal Pathogens ◽  
Crop Production ◽  
Control Strategies ◽  
Brown Rot ◽  
Management Option ◽  
Management Options ◽  
Pests And Diseases ◽  
Resistant Varieties ◽  
Rot Disease ◽  
Post Harvest Loss

The peach is one of the most important global tree crops within the economically important Rosaceae family. The crop is threatened by numerous pests and diseases, especially fungal pathogens, in the field, in transit, and in the store. More than 50% of the global post-harvest loss has been ascribed to brown rot disease, especially in peach late-ripening varieties. In recent years, the disease has been so manifest in the orchards that some stone fruits were abandoned before harvest. In Spain, particularly, the disease has been associated with well over 60% of fruit loss after harvest. The most common management options available for the control of this disease involve agronomical, chemical, biological, and physical approaches. However, the effects of biochemical fungicides (biological and conventional fungicides), on the environment, human health, and strain fungicide resistance, tend to revise these control strategies. This review aims to comprehensively compile the information currently available on the species of the fungus Monilinia, which causes brown rot in peach, and the available options to control the disease. The breeding for brown rot-resistant varieties remains an ideal management option for brown rot disease control, considering the uniqueness of its sustainability in the chain of crop production.

scholarly journals Investigation of Fungi Causing Twig Blight Diseases on Peach Trees in South Carolina

Plant Disease ◽  
2019 ◽  
Vol 103 (4) ◽  
pp. 705-710 ◽  
Author(s):  
Martha H. Froelich ◽  
Guido Schnabel
Keyword(s):  
South Carolina ◽  
Fungal Pathogens ◽  
Management Strategies ◽  
Brown Rot ◽  
Cambium Layer ◽  
Twig Blight ◽  
Botryosphaeria Obtusa ◽  
Peach Trees ◽  
Moderately Resistant ◽  
Prevalent Species

A survey of fungal pathogens causing twig blight on commercial peach trees was conducted in South Carolina in the fall of 2016. Shoots with cankers, pycnidia, and dieback were collected from six locations around the state. Isolates obtained from these samples were identified as Botryosphaeria obtusa, Phomopsis amygdali, Leucostoma persoonii, and Cytospora sp., based on colony morphology, conidia size and shape, and ribosomal DNA sequence analysis. L. persoonii was the most prevalent species and was isolated in five of the six locations, followed by P. amygdali and B. obtusa. The sensitivity of representative isolates of B. obtusa, P. amygdali, and L. persoonii to fungicides of different FRAC codes was evaluated. All species tested were sensitive to thiophanate-methyl (FRAC 1) and pyraclostrobin and azoxystrobin (both FRAC 11), whereas all species were resistant to boscalid and fluopyram (both FRAC 7). P. amygdali and B. obtusa were sensitive to difenoconazole and propiconazole (both FRAC 3), whereas L. persoonii was moderately resistant. L. persoonii was the most virulent species based on expansion of mycelium in the cambium layer of 2-year-old, detached twig pieces. Bacterial spot (BS)-sensitive cultivar ‘O’Henry’ was most susceptible to B. obtusa compared with BS-sensitive ‘Summerprince’, brown rot (BR)-resistant ‘Contender’, and BR-sensitive ‘Coronet’ but was least susceptible to L. persoonii. Coronet was most susceptible to L. persoonii. There were no significant differences between susceptibility of the cultivars to P. amygdali. This study established that L. persoonii is currently the most frequent twig blight pathogen in South Carolina, perhaps owing to its superior fitness. Some fungicides were effective in controlling all twig blight pathogens and may therefore be useful for chemical management strategies. Our study also provides the first evidence that the genetic basis of resistance to BS and BR in peach trees is not necessarily linked to tolerance to wood pathogens.

scholarly journals Droplet-based microfluidics platform for antifungal analysis against filamentous fungi

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sehrish Iftikhar ◽  
Aurélie Vigne ◽  
Julia Elisa Sepulveda-Diaz
Keyword(s):  
Fungal Pathogens ◽  
Antimicrobial Agents ◽  
Pearson Correlation ◽  
Hyphal Growth ◽  
Bulk Analysis ◽  
Single Spore ◽  
Microfluidic Platform ◽  
Viability Assay ◽  
Wide Range ◽  
Potential Applications

AbstractFungicides are extensively used in agriculture to control fungal pathogens which are responsible for significant economic impact on plant yield and quality. The conventional antifungal screening techniques, such as water agar and 96-well plates, are based on laborious protocols and bulk analysis, restricting the analysis at the single spore level and are time consuming. In this study, we present a droplet-based microfluidic platform that enables antifungal analysis of single spores of filamentous fungus Alternaria alternata. A droplet-based viability assay was developed, allowing the germination and hyphal growth of single A. alternata spores within droplets. The viability was demonstrated over a period of 24 h and the antifungal screening was achieved using Kunshi/Tezuma as antifungal agent. The efficacy results of the droplet-based antifungal analysis were compared and validated with the results obtained from conventional protocols. The percentage inhibitions assessed by the droplet-based platform were equivalent with those obtained by the other two methods, and the Pearson correlation analysis showed high correlation between the three assays. Taken together, this droplet-based microfluidic platform provides a wide range of potential applications for the analysis of fungicide resistance development as well as combinatorial screening of other antimicrobial agents and even antagonistic fungi.

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