scholarly journals Formation of sclerotia inSclerotinia ginsengand composition of the sclerotial exudate

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e6009 ◽  
Author(s):  
Dan Wang ◽  
Junfan Fu ◽  
Rujun Zhou ◽  
Zibo Li ◽  
Yujiao Xie ◽  
...  

BackgroundSclerotinia ginsengis a major devastating soil-borne pathogen of ginseng that can cause irreparable damage and large economic losses. This pathogen produces sclerotia, which are among the most persistent resting structures produced by filamentous fungi. The production of an exudate is a common feature of sclerotial development.MethodsS. ginsengwas cultured on 10 different media and the following parameters were measured: mycelial growth rate (mm/day), initial formation time of exudate droplets, total quantity of exudate, number of sclerotia per dish, and sclerotial fresh/dry weight. The composition of the sclerotial exudate was analyzed using four methods (high performance liquid chromatography, gas chromatography-mass spectrometry, flame atomic absorption spectrometry, and Nessler’s reagent spectrophotometry).ResultsWe found that PDA was the optimal medium for exudate production, while SDA medium resulted in the highest mycelial growth rate. The earliest emergence of exudate droplets from sclerotia was on OA-YE and V8 media. The largest amount of sclerotia and the smallest sclerotia were produced on V8 medium. The maximum and minimum dry/fresh weight were obtained on MEA medium and V8 medium, respectively. The exudate contained organic acids (oxalic acid, gallic acid, ferulic acid, vanillic acid, caffeic acid, and tannic acid), carbohydrates (inositol, glucose, and trehalose), various ions (potassium, sodium, and magnesium), and ammonia.DiscussionThe functions of the identified compounds are discussed within the context of pathogenicity, sclerotial development, and antimicrobial activity. Our findings provide information about the production of sclerotia and the composition of sclerotial exudate that may be useful to develop strategies to control this disease.

2011 ◽  
Vol 51 (4) ◽  
pp. 329-336 ◽  
Author(s):  
Hossein Irani ◽  
Asghar Heydari ◽  
Mohammad Javan-Nikkhah ◽  
Ağav∂li İbrahimov

Pathogenicity Variation and Mycelial Compatibility Groups inSclerotinia SclerotiorumPopulation variability ofS. sclerotiorum, the causal agent of Sclerotinia stalk rot of sunflower, was determined by mycelial compatibility grouping (MCG) and pathogenicity variation comparison. To study mycelial compatibility grouping and pathogenicity variability, isolates ofS. sclerotiorumwere collected from sunflower fields in East, West Azerbaijan and Ardebil provinces of Iran. Among 186 isolates tested, 26 MCGs were identified and 46% were represented by single isolates. There were differences among MCGs comparing mycelial growth rate, sclerotial production on PDA and aggressiveness cause disease. Significant differences were detected in number of sclerotia, dry weight of sclerotia, mycelial growth rate and aggressiveness among MCGs (p < 0.001) regardless of their geographic origins. There was generally a poor correlation (r = 0.21, p ≤ 0.05) between sclerotia weight and number of sclerotia produced on PDA and also to the mycelial growth rate at 24 (r = 0.35, p ≤ 0.05) and 48h (r = 0.39, p ≤ 0.05). Our studies in comparison of the detached leaf and cut-stem methods showed that the highest rank correlations (r = 0.78 p ≤ 0.01), while aggressiveness of two inoculation methods (stem and leaf detached) were not correlated to colony diameter growth or the other two factors. Variation in isolates aggressiveness may be important considerations in disease management systems.


2014 ◽  
Vol 45 (3) ◽  
pp. 861-872 ◽  
Author(s):  
P.C. Guadarrama-Mendoza ◽  
G. Valencia del Toro ◽  
R. Ramírez-Carrillo ◽  
F. Robles-Martínez ◽  
J. Yáñez-Fernández ◽  
...  

2018 ◽  
Vol 7 (3) ◽  
pp. 123-129 ◽  
Author(s):  
Fakher Ayed ◽  
Hayfa Jabnoun-Khiareddine ◽  
Rania Aydi-Ben-Abdallah ◽  
Mejda Daami-Remadi

Sclerotium rolfsii is one of the devastating soilborne fungus responsible for significant plant losses. The effects of pH and aeration on pathogen mycelial growth, sclerotial production and germination were investigated for three Tunisian isolates. Optimal mycelial growth occurred at pH 6 for Sr2 and Sr3 isolates and at pH 6-7 for Sr1. Dry mycelial growth was optimum at pH values ranging between 4 and 7. Sclerotial initiation started on the 3rd day of incubation at all pH values tested and mature sclerotia were formed after 6 to 12 days. Optimal sclerotial production was noted at pH 5. The dry weight of 100 sclerotia varied depending on isolates and pH and occurred at pH range 4-7. At pH 9, mycelial growth, sclerotial production and dry weight of 100 sclerotia were restricted. The optimum sclerotial germination, noted after 24 h of incubation, varied depending on isolates and pH and occurred at pH 4-9. Mycelial growth was optimum in aerated plates with a significant isolates x aeration treatments interaction. Sclerotial initiation occurred at the 3rd day of incubation and mature sclerotia were observed after 6-9 days. Sclerotial development was very slow in completely sealed plates and dark sclerotia were produced only after 15 days of incubation. The highest sclerotial yields were noted in aerated plates. The highest dry weight of 100 sclerotia for Sr1 isolate was recorded in ½ sealed, no sealed and completely sealed plates, while for Sr2, it was noted in ½ and ⅔ sealed plates. For Sr3, the maximum dry weight of 100 sclerotia was recorded in ½, ⅔ and completely sealed plates. Germination of S. rolfsii sclerotia, after 24 h of incubation, did not vary significantly depending on aeration treatments and ranged from 90 to 100% for all isolates.


2019 ◽  
Vol 70 (8) ◽  
pp. 2803-2804
Author(s):  
George A. Draghici ◽  
Cristina A. Dehelean ◽  
Iulia Pinzaru ◽  
Despina M. Bordean ◽  
Georgeta Pop ◽  
...  

Cadmium is very hazardous pollutant with massive impact on aspects of everyday life. Little knowledge exists on kinetics of dietary cadmium retention in Cantareus aspersus for durations above three months although this species of land snails serves as excellent ecotoxicological model for studying cadmium hazard. Here was used a continuous 112-day exposure study design, in which test snails were exposed to a wide range of dietary cadmium levels, including human- and environmentally-relevant levels. Using Flame Atomic Absorption Spectrometry, cadmium levels in the hepatopancreas were found to increase significantly, and in dose-dependent manner starting from a dietary cadmium dose of 0.2 mg/kg dry weight. The results of the present study render the hepatopancreas of mature snails, C. aspersus, as excellent endpoints for assessing Cd toxicity over a broad range of concentrations. Hence, this species of land snails can be reliably used for both active and passive biomonitoring of environmental cadmium pollution.


2020 ◽  
Vol 56 (No. 2) ◽  
pp. 74-82 ◽  
Author(s):  
Antonios Zambounis ◽  
Oksana Sytar ◽  
Dimitris Valasiadis ◽  
Zoe Hilioti

The phytopathogenic oomycetes of the genus Phytophthora cause devastating economic losses worldwide.<br />Naphthodianthrone compounds, present in plant extracts of buckwheat and Saint John’s wort act as photosensitiser<br />agents and exhibit antimicrobial activity against a number of pathogens. In this study, we investigated the potential<br />inhibitory effects of fagopyrin and hypericin on Phytophthora citrophthora (R.E. Sm. &amp; E.H. Sm.) Leonian 1906, the<br />main causal agent of rot diseases in deciduous trees. Fagopyrin had the highest inhibitory effect in the colony growth<br />at a concentration of 2% of a stock solution (3 mg/mL), inducing clubbed hyphae with round tips. Notably, hypericin<br />also inhibited the radial colony growth and increased the hyphal branching at the subapical region, while also promoting<br />the formation of enlarged cells with irregular shapes growing collectively as biofilm-like structures. In terms of the<br />mycelial dry weight, although both photosensitisers had considerable inhibitory effects, the fagopyrin treatment was<br />most effective. Leaf bioassays showed that under dark conditions the photosensitiser pre-treated zoospores formed a<br />dense, but aberrant, mycelial growth with penetration defects. In contrast, when the zoospore production was performed<br />under light conditions, the zoospores failed to cause necrotic lesions and penetration events implying that their<br />virulence was impaired. These findings shed light on the biological effects of fagopyrin and hypericin in the regulation<br />of the mycelial growth, morphology and pathogenicity of P. citrophthora.


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