Fungicide Impact on in vitro Germination of Basidiospores of Puccinia horiana, the Causal Agent of Chrysanthemum White Rust

2015 ◽  
Vol 16 (2) ◽  
pp. 73-76 ◽  
Author(s):  
C. L. Palmer ◽  
M. R. Bonde ◽  
S. E. Nester ◽  
J. M. Revell ◽  
D. G. Luster
Keyword(s):  
Mode Of Action ◽  
Causal Agent ◽  
In Vitro Germination ◽  
Resistance Development ◽  
Fungicide Sensitivity ◽  
White Rust ◽  
Petri Plate ◽  
Puccinia Horiana ◽  
Over Time

Puccinia horiana is an actionable pathogen that, upon diagnosis, triggers an eradication protocol combining destruction of symptomatic chrysanthemums and a strict fungicide regime for asymptomatic plants. Symptoms typically appear during the fall as growers prepare to ship their crops. To expand the list of effective fungicides and develop fungicide sensitivity baselines, we screened in vitro germination of P. horiana basidiospores in 0.05% water agar solution amended with varying concentrations of 14 fungicides: azoxystrobin, boscalid + pyraclostrobin, fluoxastrobin, mancozeb, mandestrobin, metconazole, myclobutanil, propiconazole, tebuconazole, triadimefon, trifloxystrobin, trifloxystrobin + triadimefon, and triticonazole. Leaves with pustules ready to sporulate were affixed to petri plate lids over bases containing fungicide-amended agar. After 2 days in the dark, percent basidiospore germination was assessed. Concentrations required for 50% germination (EC50) grouped according to fungicide mode of action. Benzimidazoles exhibited EC50 values ranging from 9 to 244 ppm, while strobilurins ranged from 2 to 27 ppb. Mancozeb exhibited an EC50 of 7 ppm, and chlorothalonil was 205 ppb. Combinations of strobilurins with other modes of action exhibited EC50 values in the same range as the strobilurins. These data provide a baseline for monitoring resistance development to P. horiana over time. Accepted for publication 15 January 2015. Published 7 April 2015.

scholarly journals Cladosporium cladosporioides and Cladosporium pseudocladosporioides as potential new fungal antagonists of Puccinia horiana Henn., the causal agent of chrysanthemum white rust

PLoS ONE ◽  
2017 ◽  
Vol 12 (1) ◽  
pp. e0170782 ◽  
Author(s):  
David Eduardo Torres ◽  
Reyna Isabel Rojas-Martínez ◽  
Emma Zavaleta-Mejía ◽  
Patricia Guevara-Fefer ◽  
G. Judith Márquez-Guzmán ◽  
...  
Keyword(s):  
Cladosporium Cladosporioides ◽  
Causal Agent ◽  
White Rust ◽  
Puccinia Horiana

scholarly journals Germination of Mansonia altissima (A. Chev.) A. Chev. var. altissima: an endangered valuable timber species in Africa

2020 ◽  
Vol 42 ◽  
pp. e47448
Author(s):  
Ojo Michael Oseni ◽  
Tapan Kumar Nailwal ◽  
Veena Pande
Keyword(s):  
Statistical Analysis ◽  
Seed Germination ◽  
Timber Species ◽  
Ms Medium ◽  
In Vitro Germination ◽  
Petri Plate ◽  
Disease Free ◽  
Seeds Germination

The in vitro seed germination which results in the production of disease-free seedlings and greenhouse germination of the seeds of Mansonia altissima was investigated in order to establish a better way of germination of the timber species. Five levels of GA3 treatment were used in in vitro germination with three replicate and two seeds were inoculated in each of the jam bottle. Whereas, in greenhouse germination, five levels of different treatments were used, replicated three times and each Petri plate contained 15 seeds. The experiment was repeated twice and the data from each experiment was put together and used for the statistical analysis. The results showed that seeds germination occurred eight days after inoculation in in vitro but in the case of greenhouse germination, it took only five days. For in vitro rapid germination of Mansonia altissima, the MS medium should be supplemented with 1.0 μm of GA3. Equally, in greenhouse germination, the seeds need to be soaked in 1.0 mM of GA3 for 24 hours. Alternatively, in the absence of GA3, the seeds can be soaked in water for 24 hours before broadcasting the seeds on the seedbed for germination, as this will help to identify nonviable seeds.

Comparing the Fungicide Sensitivity of Sclerotinia sclerotiorum Using Mycelial Growth and Ascospore Germination Assays

Plant Disease ◽  
2021 ◽  
Author(s):  
Miller da Silva Lehner ◽  
Kaique Alves ◽  
Emerson Medeiros Del Ponte ◽  
Sarah Jane Pethybridge
Keyword(s):  
Sclerotinia Sclerotiorum ◽  
Mode Of Action ◽  
Mycelial Growth ◽  
White Mold ◽  
Fungicide Sensitivity ◽  
Snap Bean ◽  
Thiophanate Methyl ◽  
Ascospore Germination ◽  
Sensitivity Tests

The infection of the floral tissues of snap bean and other crops by Sclerotinia sclerotiorum, the causative agent of white mold, is by ascospores. Irrespective of the fungicide mode of action being evaluated, in vitro fungicide sensitivity tests are conducted almost exclusively using mycelial growth assays. This is likely due to difficulties and time involved in sclerotial conditioning required to produce apothecia and ascospores. The objective of this research was to compare estimates of fungicide sensitivity between mycelial growth and ascospore germination assays for S. sclerotiorum. Sensitivity assays were conducted using serial doses of three fungicides commonly used to control white mold: boscalid, fluazinam, and thiophanate-methyl. A total of 27 isolates were evaluated in replicated trials conducted for each fungicide and assay type. The effective concentration to reduce mycelial growth or ascospore germination by 50% (EC50) was estimated for each isolate, fungicide, assay type, and trial. The median EC50 values obtained from ascospore germination assays were 52.7, 10.0, and 2.7 times higher than those estimated from the mycelial growth for boscalid, fluazinam, and thiophanate-methyl, respectively. No significant correlation was found between EC50 values estimated by the two methods. These findings highlight differences that may be important in evaluating the sensitivity of S. sclerotiorum given the fungicide mode of action and how they will be used in the field.

scholarly journals Mode of Action,In VitroActivity, andIn VivoEfficacy of AFN-1252, a Selective Antistaphylococcal FabI Inhibitor

2012 ◽  
Vol 56 (11) ◽  
pp. 5865-5874 ◽  
Author(s):  
Nachum Kaplan ◽  
Monique Albert ◽  
Donald Awrey ◽  
Elias Bardouniotis ◽  
Judd Berman ◽  
...  
Keyword(s):  
Mode Of Action ◽  
Fatty Acid Biosynthesis ◽  
Acyl Carrier Protein ◽  
Pharmacokinetic Studies ◽  
Coagulase Negative Staphylococci ◽  
Resistance Development ◽  
Content Type ◽  
Peritoneal Infection

ABSTRACTThe mechanism of action of AFN-1252, a selective inhibitor ofStaphylococcus aureusenoyl-acyl carrier protein reductase (FabI), which is involved in fatty acid biosynthesis, was confirmed by using biochemistry, macromolecular synthesis, genetics, and cocrystallization of an AFN-1252–FabI complex. AFN-1252 demonstrated a low propensity for spontaneous resistance development and a time-dependent reduction of the viability of both methicillin-susceptible and methicillin-resistantS. aureus, achieving a ≥2-log10reduction inS. aureuscounts over 24 h, and was extremely potent against clinical isolates ofS. aureus(MIC90, 0.015 μg/ml) and coagulase-negative staphylococci (MIC90, 0.12 μg/ml), regardless of their drug resistance, hospital- or community-associated origin, or other clinical subgroup. AFN-1252 was orally available in mouse pharmacokinetic studies, and a single oral dose of 1 mg/kg AFN-1252 was efficacious in a mouse model of septicemia, providing 100% protection from an otherwise lethal peritoneal infection ofS. aureusSmith. A median effective dose of 0.15 mg/kg indicated that AFN-1252 was 12 to 24 times more potent than linezolid in the model. These studies, demonstrating a selective mode of action, potentin vitroactivity, andin vivoefficacy, support the continued investigation of AFN-1252 as a targeted therapeutic for staphylococcal infections.

SC5005 dissipates the membrane potential to kill Staphylococcus aureus persisters without detectable resistance

2021 ◽  
Author(s):  
Chieh-Hsien Lu ◽  
Chung-Wai Shiau ◽  
Yung-Chi Chang ◽  
Hsiu-Ni Kung ◽  
Jui-Ching Wu ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Mode Of Action ◽  
Cytoplasmic Membrane ◽  
Resistance Development ◽  
Antibiotic Resistant ◽  
Atp Production ◽  
The Past ◽  
Ht 29

Abstract Objectives In the past few decades, multiple-antibiotic-resistant Staphylococcus aureus has emerged and quickly spread in hospitals and communities worldwide. Additionally, the formation of antibiotic-tolerant persisters and biofilms further reduces treatment efficacy. Previously, we identified a sorafenib derivative, SC5005, with bactericidal activity against MRSA in vitro and in vivo. Here, we sought to elucidate the resistance status, mode of action and anti-persister activity of this compound. Methods The propensity of S. aureus to develop SC5005 resistance was evaluated by assessment of spontaneous resistance and by multi-passage selection. The mode of action of SC5005 was investigated using macromolecular synthesis, LIVE/DEAD and ATPlite assays and DiOC2(3) staining. The effect of SC5005 on the mammalian cytoplasmic membrane was measured using haemolytic and lactate dehydrogenase (LDH) assays and flow cytometry. Results SC5005 depolarized and permeabilized the bacterial cytoplasmic membrane, leading to reduced ATP production. Because of this mode of action, no resistance of S. aureus to SC5005 was observed after constant exposure to sub-lethal concentrations for 200 passages. The membrane-perturbing activity of SC5005 was specific to bacteria, as no significant haemolysis or release of LDH from human HT-29 cells was detected. Additionally, compared with other bactericidal antibiotics, SC5005 exhibited superior activity in eradicating both planktonic and biofilm-embedded S. aureus persisters. Conclusions Because of its low propensity for resistance development and potent persister-eradicating activity, SC5005 is a promising lead compound for developing new therapies for biofilm-related infections caused by S. aureus.

scholarly journals Morphology of Puccinia horiana, Causal Agent of Chrysanthemum White Rust, Sampled From Naturally Infected Plants

Plant Disease ◽  
2015 ◽  
Vol 99 (12) ◽  
pp. 1738-1743 ◽  
Author(s):  
G. O’Keefe ◽  
D. D. Davis
Keyword(s):  
Chrysanthemum Morifolium ◽  
Linear Pattern ◽  
White Rust ◽  
Internal Cell ◽  
High Infection ◽  
Commercially Important ◽  
Close Relatives ◽  
Puccinia Horiana ◽  
Germ Tubes

Chrysanthemum white rust (CWR), caused by Puccinia horiana, is pathogenic on many Chrysanthemum spp. and close relatives, and infects commercially important florist chrysanthemum cultivars (Chrysanthemum × morifolium) throughout the world. Due to regulations, most research and observations with CWR are done in vitro with symptomatic plants. In contrast, research presented herein is based on microscopic examination of symptomatic and asymptomatic plants collected from natural outbreaks in the field. We observed scattered (not in a linear pattern) telial sori on infected chrysanthemum leaves, stems, and flowers that coalesced at high infection levels. Teliospores were mainly two-celled but occasionally one- or three-celled. Promycelia arose from the apical teliospore cell, the basal cell, or both. The number of basidiospores on promycelia varied from one to four. Germ tubes, arising from P. horiana basidiospores, penetrated the host epidermis directly without appressoria. A mucilaginous exudate formed at the site of attachment and penetration of leaf and stem tissue, as well as on internal cell walls. P. horiana colonization was systemic, with intercellular mycelium and intracellular M-haustoria in both symptomatic and asymptomatic infected host tissue. Hyphal anastomosis was observed within infected plants, suggesting that asexual fusion between different P. horiana pathotypes or genotypes might occur.

scholarly journals First Confirmed Report that Puccinia horiana, Causal Agent of Chrysanthemum White Rust, Can Overwinter in Pennsylvania

Plant Disease ◽  
2012 ◽  
Vol 96 (9) ◽  
pp. 1381-1381 ◽  
Author(s):  
G. O'Keefe ◽  
D. D. Davis
Keyword(s):  
United States ◽  
Molecular Analysis ◽  
Tap Water ◽  
Signs And Symptoms ◽  
The United States ◽  
Causal Agent ◽  
Controlled Environment ◽  
White Rust ◽  
Environment Chamber ◽  
Puccinia Horiana

Chrysanthemum white rust (CWR) is a quarantine-significant pest in the United States (Title 7, Code of Federal Regulations, Part 319.37-2). The causal agent of CWR, Puccinia horiana Henn., is an autoecious, microcyclic rust that is pathogenic on chrysanthemum species (Chrysanthemum spp.) and close relatives within the family Asteraceae. CWR is indigenous to Japan, where it was first reported in 1895 (4). By the 1960s, CWR was found throughout Europe and later spread to Africa, Oceana, South America, and other parts of Asia. In North America, CWR was reported in Mexico and in the United States (New Jersey and Pennsylvania [1977], Oregon and Washington [1990], and California [1991]). Additional detections of CWR were later reported in 22 Pennsylvania counties (2004, 2006 to 2010) (3). These later Pennsylvania reports stated that eradication was attempted at some sites, but unconfirmed observations suggested that the rust pathogen might overwinter in volunteer plants (3). Since “CWR is known to overwinter in Europe where chrysanthemums overwinter (average minimum temperatures ranging from –10°F to 10°F)” (2), the unconfirmed Pennsylvania observations prompted us to determine if P. horiana can overwinter in Pennsylvania. During October 2010, we identified CWR on perennial mums planted at six outdoor garden locations in University Park, PA. Symptomatic plants were quarantined and eradication attempted. Eradicated sites were routinely surveyed and CWR confirmed in July 2011 on volunteer plants at two of the originally infested sites. An additional outdoor garden site with CWR was observed in State College, PA, during October 2011 and eradication attempted. The three infested sites were surveyed throughout the fall and winter of 2011 to 2012. During February 2012, two asymptomatic volunteer plants arising from root pieces were collected from each of the three sites. Each sample was washed with tap water to remove excess soil, examined morphologically, surface sterilized with 10% bleach, and divided into two subsamples. One subsample from each site was divided into crown and root portions and DNA extracted using a Qiagen DNeasy Plant Mini Kit. Molecular analysis was performed using modifications of published primers ITS 5 and Rust1 (1,4). Puccinia horiana was detected in plant roots from one site and in plant crowns from two sites. The remaining two subsamples from each site were transplanted into sterilized potting soil and placed in a clean controlled environment chamber at 18°C and 85% relative humidity (RH). After 6 weeks, six actively growing plants were transferred to a second clean controlled environment chamber at 17°C and 90 to 100% RH. On 6 April 2012, CWR symptoms and signs were confirmed morphologically on two plants that had been removed from one site. On 19 April 2012, CWR signs and symptoms were confirmed morphologically and by molecular analysis on leaves of volunteer plants at one University Park site. DNA extractions were sequenced and shared a 100% maximum identity to a known P. horiana accession (EU816920.1) in GenBank. To our knowledge, this is the first confirmed report of P. horiana overwintering in Pennsylvania. References: (1) H. Alaei et al. Mycol. Res. 113:668, 2009. (2) Anon. Chrysanthemum White Rust Bulletin, Syngenta Flowers Inc., Gilroy, CA, 2010. (3) S. Kim et al. Phytopathology 101:S91, 2011. (4) K. Pedley. Plant Dis. 93:1252, 2009.

scholarly journals Evidence for Systemic Infection by Puccinia horiana, Causal Agent of Chrysanthemum White Rust, in Chrysanthemum

2015 ◽  
Vol 105 (1) ◽  
pp. 91-98 ◽  
Author(s):  
M. R. Bonde ◽  
C. A. Murphy ◽  
G. R. Bauchan ◽  
D. G. Luster ◽  
C. L. Palmer ◽  
...  
Keyword(s):  
United States ◽  
Cell Walls ◽  
Vascular Tissue ◽  
Mesophyll Cell ◽  
The United States ◽  
Causal Agent ◽  
Control Measures ◽  
Mesophyll Cells ◽  
White Rust ◽  
Puccinia Horiana

Puccinia horiana, causal agent of the disease commonly known as chrysanthemum white rust (CWR), is a quarantine-significant fungal pathogen of chrysanthemum in the United States and indigenous to Asia. The pathogen was believed to have been eradicated in the United States but recently reappeared on several occasions in northeastern United States. The objective of the study presented here was to determine whether P. horiana could systemically infect chrysanthemum plants, thus providing a means of survival through winters. Scanning and transmission electron microscopy revealed the development of P. horiana on the surface and within leaves, stems, or crowns of inoculated chrysanthemum plants artificially exposed to northeastern U.S. winter temperatures. P. horiana penetrated leaves directly through the cuticle and then colonized the mesophyll tissue both inter- and intracellularly. An electron-dense material formed at the interface between fungal and host mesophyll cells, suggesting that the pathogen adhered to the plant cells. P. horiana appeared to penetrate mesophyll cell walls by enzymatic digestion, as indicated by the absence of deformation lines in host cell walls at penetration sites. The fungus was common in vascular tissue within the infected crown, often nearly replacing the entire contents of tracheid cell walls. P. horiana frequently passed from one tracheid cell to an adjacent tracheid cell by penetration either through pit pairs or nonpitted areas of the cell walls. Individual, presumed, fungal cells in mature tracheid cells of the crown and stems arising from infected crowns suggested that the pathogen might have been moving at least partially by means of the transpiration stream. The demonstration that chrysanthemum plants can be systemically infected by P. horiana suggests that additional disease control measures are required to effectively control CWR.

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