Studying the Ability of Thymol to Improve Fungicidal Effects of Tebuconazole and Difenoconazole Against Some Plant Pathogenic Fungi in Seed or Foliar Treatments

Thymol, a secondary plant metabolite possessing antifungal and chemosensitizing activities, disrupts cell wall or membrane integrity and interferes with ergosterol biosynthesis. Thymol also functions as a redox-active compound inducing generation of reactive oxygen species and lipid peroxidation in fungal cells. Previously, we showed thymol significantly enhanced the in vitro growth inhibitory effect of difenoconazole against Bipolaris sorokiniana and Parastagonospora nodorum. More recently, we demonstrated a possibility to use thymol to overcome the resistance of a P. nodorum strain able to grow on difenoconazole-containing media. However, potential for thymol to serve as a chemosensitizing agent in seed or plant treatments, to provide an effective suppression of the above-mentioned plant pathogens by triazole fungicides applied in lowered dosages, had yet to be tested. In the work presented here, we showed combined treatments of naturally infected barley seeds with thymol and difenoconazole (Dividend® 030 FS) synergistically exacerbated the protective effect against common root rot agent, B. sorokiniana, and other fungi (Fusarium spp. and Alternaria spp.). Similarly, co-applied treatment of wheat seeds, artificially inoculated with Fusarium culmorum, resulted in equivalent reduction of disease incidence on barley seedlings as application of Dividend®, alone, at a ten-fold higher dosage. In foliar treatments of wheat seedlings, thymol combined with Folicur® 250 EC (a.i. tebuconazole) enhanced sensitivity of P. nodorum, a glume/leaf blotch pathogen, to the fungicide and provided a significant mitigation of disease severity on treated seedlings, compared to controls, without increasing Folicur® dosages. Folicur® co-applied with thymol was also significantly more effective against a strain of P. nodorum tolerant to Folicur® alone. No additional deoxynivalenol or zearalenone production was found when a toxigenic F. culmorum was cultured in a nutrient medium containing thymol at a concentration used for chemosensitization of root rot agents. Accordingly, F. culmorum exposure to thymol at the sensitizing concentration did not up-regulate key genes associated with the biosynthesis of trichothecene or polyketide mycotoxins in this pathogen. Further studies using field trials are necessary to determine if thymol-triazole co-applications result in sensitization of seed- and foliar-associated plant pathogenic fungi, and if thymol affects production of fusarial toxins under field conditions.

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Using Commercial Compost as Control Measures against Cucumber Root-Rot Disease

Journal of Mycology ◽

10.1155/2013/324570 ◽

2013 ◽

Vol 2013 ◽

pp. 1-13 ◽

Cited By ~ 7

Author(s):

Kamel Kamal Sabet ◽

Magdy Mohamed Saber ◽

Mohamed Adel-Aziz El-Naggar ◽

Nehal Samy El-Mougy ◽

Hatem Mohamed El-Deeb ◽

...

Keyword(s):

Root Rot ◽

Control Measure ◽

Disease Incidence ◽

Pathogenic Fungi ◽

Pythium Ultimum ◽

Control Measures ◽

Infested Soil ◽

Fungal Isolates ◽

Cucumber Root

Five commercial composts were evaluated to suppress the root-rot pathogens (Fusarium solani (Mart.) App. and Wr, Pythium ultimum Trow, Rhizoctonia solani Kuhn, and Sclerotium rolfsii Sacc.) of cucumber plants under in vitro and greenhouse conditions. In vitro tests showed that all tested unautoclaved and unfiltrated composts water extracts (CWEs) had inhibitor effect against pathogenic fungi, compared to autoclaved and filtrated ones. Also, the inhibitor effects of 40 bacteria and 15 fungi isolated from composts were tested against the mycelial growth of cucumber root-rot pathogens. Twenty two bacteria and twelve fungal isolates had antagonistic effect against root-rot pathogens. The antagonistic fungal isolates were identified as 6 isolates belong to the genus Aspergillus spp., 5 isolates belong to the genus Penicillium spp. and one isolate belong to the genus Chaetomium spp. Under greenhouse conditions, the obtained results in pot experiment using artificial infested soil with cucumber root-rot pathogens showed that the compost amended soil reduced the percentage of disease incidence, pathogenic fungi population, and improved the cucumber vegetative parameters as shoot length, root length, fresh weight, and dry weight. These results suggested that composts are consequently considered as control measure against cucumber root-rot pathogens.

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Two Polyketides Produced by Endophytic Penicillium citrinum DBR-9 From Medicinal Plant Stephania kwangsiensis and Their Antifungal Activity Against Plant Pathogenic Fungi

Natural Product Communications ◽

10.1177/1934578x19846795 ◽

2019 ◽

Vol 14 (5) ◽

pp. 1934578X1984679 ◽

Cited By ~ 2

Author(s):

Haiyu Luo ◽

Zhen Qing ◽

Yecheng Deng ◽

Zhiyong Deng ◽

Xia’an Tang ◽

...

Keyword(s):

Medicinal Plant ◽

Membrane Integrity ◽

Pathogenic Fungi ◽

Significant Inhibition ◽

Penicillium Citrinum ◽

Plant Pathogenic Fungi ◽

Fungal Cell ◽

Cell Membrane Integrity ◽

Chinese Medicinal Plant

Endophytic fungi, especially those found in medicinal plants, are widely studied as producers of secondary metabolites of biotechnological interest. In this study, on the basis of an activity-directed isolation method and spectroscopic analysis, two active polyketides, citrinin (1) and emodin (2), were isolated and identified from the fermentation of the endophytic fungus Penicillium citrinum DBR-9. This fungus was isolated from the root tubers of the traditional Chinese medicinal plant Stephania kwangsiensis. In vitro antifungal assay showed that the two polyketides displayed significant inhibition on hypha growth of tested plant pathogenic fungi with IC50 values ranging from 3.1 to 123.1 μg/mL and 3.0 to 141.0 μg/mL, respectively. In addition, the mechanism of the effects of emodin (2) on the pathogen revealed it could affect the colony morphology, destroy cell membrane integrity, and influence the protein synthesis of the tested fungal cell. This work is the first report of two polyketides-producing endophytic P. citrinum DBR-9 from the medicinal plant S. kwangsiensis. Our results present new opportunities to deeply understand the potential of these two polyketides as natural antifungal agents to control phytopathogens in agriculture.

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Synthesis and Evaluation of Isatin Schiff Bases Against Plant Pathogens Validated Through Aspartyl Protease and Acetylcholine Binding Proteins Docked Studies

Letters in Organic Chemistry ◽

10.2174/1570178618666210610160546 ◽

2021 ◽

Vol 18 ◽

Author(s):

Shivani Loomba ◽

Divya Utreja ◽

Komalpreet Kaur ◽

Jaspal Kaur ◽

Shivali Sharma ◽

...

Keyword(s):

Schiff Bases ◽

Plant Pathogens ◽

Binding Proteins ◽

Docking Simulation ◽

In Vitro Study ◽

Pathogenic Fungi ◽

Bipolaris Sorokiniana ◽

Aspartyl Protease ◽

Acetylcholine Binding Proteins

: Schiff bases of isatin were synthesized by reacting isatin with substituted aromatic amines and were characterized by UV-Visible, 1HNMR, 13CNMR, IR, and microanalytical data. All the synthesized isatin Schiff bases were screened in vitro against wheat pathogenic fungi Bipolaris sorokiniana, Alternaria triticina using spore inhibition technique and brinjal parasite- Meloidogyne incognita by egg hatch inhibition and J2 mortality. The in vitro study and docking simulation studies revealed that the 3-(2,4,5-trichlorophenylimino)indolin-2-one 6f and 3-(2,4-dinitrophenylimino)indolin-2-one 6c substituted with tri-halogen and dinitro electron-withdrawing groups were found to be promising antipathogenic candidates. The possible binding interactions of tested compounds with Aspartyl protease and Acetylcholine binding proteins were analyzed through molecular docking.

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Colloidal Silver Hydrogen Peroxide: New Generation Molecule for Management of Phytopathogens

Horticulturae ◽

10.3390/horticulturae7120573 ◽

2021 ◽

Vol 7 (12) ◽

pp. 573

Author(s):

Hosapura Shekhararaju Mahesha ◽

Jayasuvarnapura Umapathi Vinay ◽

Medikeripura Rekhyanaik Ravikumar ◽

Suryanarayana Visweswarashastry ◽

Manikyanahalli Chandrashekhara Keerthi ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Crop Production ◽

Plant Pathogens ◽

Pathogenic Fungi ◽

Field Studies ◽

Plant Pathogenic Fungi ◽

Mycelium Growth ◽

Average Size ◽

New Generation

Plant pathogenic fungi and bacteria are a significant threat to global commercial crop production resulting in increased cost of production, reduced crop establishment and productivity. An effort was made to study the antimicrobial activity of silver hydrogen peroxide (SHP) against selected plant pathogenic fungi and bacteria under in vitro conditions. Higher antibacterial activity of SHP was observed against Xanthomonas axonopodis pv. citri (Xac; 39.67 mm), Xanthomonas citri pv. punicae (Xap; 39.00 mm), and Ralstonia solanacearum (Rs; 36.67 mm) at 500 ppm concentration. SHP was superior to streptocycline (500 ppm) against Xac (25.33 mm) and Xcp (22.67 mm) at 100 ppm. The soil-borne fungi viz., Pythium aphanidermatum and Fusarium solani failed to initiate mycelium growth on PDA at the concentration of 5000 ppm and above. The average size of SHP particles was 462 nm in diameter, and 73.40% of particles had the size of 378 nm, which reflects the particles present in SHP solution in the form of colloids. The effective doses (100–5000 ppm) did not show any phytotoxicity symptoms in plants, while leaf necrosis was noticed at 10,000 ppm after four days of application. SHP (≤5000 ppm) can be used to effectively manage both fungal and bacterial plant pathogens by a single application. Further field studies need to be conducted for validation and commercial use of SHP.

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Tulbaghia violacea L. II: In vivo antifungal properties towards plant pathogens

Australian Journal of Agricultural Research ◽

10.1071/ar05320 ◽

2006 ◽

Vol 57 (5) ◽

pp. 517 ◽

Cited By ~ 9

Author(s):

Leeto Nteso ◽

Johan C. Pretorius

Keyword(s):

Crude Extract ◽

Seed Treatment ◽

Plant Pathogens ◽

Disease Incidence ◽

Ascochyta Blight ◽

Pathogenic Fungi ◽

Positive Control ◽

Mycosphaerella Pinodes

In vitro antifungal activity of crude extracts from Tulbaghia violacea against 6 economically important plant pathogenic fungi was previously reported. The in vivo control of Mycosphaerella pinodes, causative of Ascochyta blight, by different concentrations of a crude aerial part extract of T. violacea was subsequently followed qualitatively and quantitatively in terms of lesions that developed over a 6-day period at 20°C on detached pea (Pisum sativum) leaves. Infection by M. pinodes spores was prevented when the extract was applied both before and after inoculation, confirming complete inhibition of spore germination, whereas no phytotoxic effect was observed on the leaves. Additionally, the control of sorghum covered (Sporisorium sorghi) and loose (S. cruentum) kernel smuts by seed treatment with the crude extract was tested under field conditions. Before planting, different sorghum seed lots were inoculated separately with spores from the 2 pathogens at a rate of 0.5% per kg (w/w), followed by treatment with the crude extract, at a concentration of 2.0 mg/mL, 24 h later. A standard fungicide, Thiram (65 W), was applied as a positive control at a rate of 0.25% per kg (v/w). Disease incidence was quantified during harvest and expressed as percentage infected plants. Seed treatment with the extract significantly (P < 0.05) reduced the incidence of both sorghum loose and covered smut diseases, compared favourably with the standard fungicide, and resulted in significant yield increases compared to the untreated control.

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Soil Chitinolytic Bacteria from Jambi Province to Produce Antifungal of Plant Pathogens

Mangifera Edu ◽

10.31943/mangiferaedu.v5i1.95 ◽

2020 ◽

Vol 5 (1) ◽

pp. 26-37

Author(s):

Risky Hadi Wibowo ◽

Sipriyadi Sipriyadi ◽

Nisa Rachmania Mubarik ◽

Iman Rusmana

Keyword(s):

Plant Pathogens ◽

Biological Control Agent ◽

Sclerotium Rolfsii ◽

Morphological Characteristics ◽

Pathogenic Fungi ◽

Plant Pathogenic Fungi ◽

Fungal Cell ◽

Chitinolytic Bacteria ◽

Agar Media

Chitinolytic bacteria are bacteria that have chitinolytic activity, which is able to hydrolysis the composition of chitin which composes many fungal cell walls. Chitinolytic bacteria are currently more widely used because of their ability as a biological control agent to the pathogenic fungi especially in horticultural and plantation crops. This research was conducted with the aim of obtaining isolates of chitinolytic bacteria that were able to inhibit the growth of plant pathogenic fungi in Vitro on chitin agar media. Fusarium oxysporum, Sclerotium rolfsii, and Rhizoctonia solanii are used in the inhibition test of chitinolytic bacteria. Bacteria were isolated and screened from the soil of Bukit Dua Belas National Park and Oil Palm Plantations in Jambi using 0.3% chitin agar media. The results showed that two of 10 bacterial isolates were able to produce inhibition zones to the growth of hyphae of pathogenic fungi on potato dextrose agar (PDA) media. TB04-13 isolate was able to produce the largest inhibition in F. oxysporum and R. solanii about 42% and 42.05% respectively, while TB04-15 isolate produced the biggest inhibition in S. Rolfsii ranged to 25.50%. Based on the chitinolytic index (CI) values, isolates TB04-13 and TB04-15 produced CI values of 1.60 and 0.63, respectively. The morphological characteristics and Gram staining of both TB04-13 and TB04-15 chitinolytic isolates are included in rod-shaped and Gram-positive bacteria. Both of these isolates can be used as antifungal-producing candidates for plant pathogenic fungi in Indonesia.

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Antagonistic Strain Bacillus amyloliquefaciens XZ34-1 for Controlling Bipolaris sorokiniana and Promoting Growth in Wheat

Pathogens ◽

10.3390/pathogens10111526 ◽

2021 ◽

Vol 10 (11) ◽

pp. 1526

Author(s):

Yanjie Yi ◽

Youtian Shan ◽

Shifei Liu ◽

Yanhui Yang ◽

Yang Liu ◽

...

Keyword(s):

Biological Control ◽

Root Rot ◽

Bacillus Amyloliquefaciens ◽

Biological Control Agent ◽

Wheat Yield ◽

Bipolaris Sorokiniana ◽

Common Root ◽

Bioactive Substances ◽

Wheat Seedlings ◽

Common Root Rot

Common root rot, caused by Bipolaris sorokiniana, is one of the most prevalent diseases of wheat and has led to major declines in wheat yield and quality worldwide. Here, strain XZ34-1 was isolated from soil and identified as Bacillus amyloliquefaciens based on the morphological, physiological, biochemical characteristics and 16S rDNA sequence. Culture filtrate (CF) of strain XZ34-1 showed a high inhibition rate against B.sorokiniana and had a broad antifungal spectrum. It also remarkably inhibited the mycelial growth and spore germination of B. sorokiniana. In pot control experiments, the incidence and disease index of common root rot in wheat seedlings were decreased after treatment with CF, and the biological control efficacy was significant, up to 78.24%. Further studies showed XZ34-1 could produce antifungal bioactive substances and had the potential of promoting plant growth. Lipopeptide genes detection with PCR indicated that strain XZ34-1 may produce lipopeptides. Furthermore, activities of defense-related enzymes were enhanced in wheat seedlings after inoculation with B.sorokiniana and treatment with CF, which showed induced resistance could be produced in wheat to resist pathogens. These results reveal that strain XZ34-1 is a promising candidate for application as a biological control agent against B.sorokiniana.

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Black Root Rot Caused by Thielaviopsis basicola on Lettuce in California

Plant Disease ◽

10.1094/pdis-92-9-1368a ◽

2008 ◽

Vol 92 (9) ◽

pp. 1368-1368 ◽

Cited By ~ 1

Author(s):

S. T. Koike

Keyword(s):

Root Rot ◽

Disease Incidence ◽

Control Plant ◽

Pathogenic Fungi ◽

Plant Roots ◽

Peat Moss ◽

Thielaviopsis Basicola ◽

Black Root Rot ◽

Iceberg Lettuce ◽

Salinas Valley

In 2005 and 2006, field-grown iceberg lettuce (Lactuca sativa) in California's coastal Salinas Valley (Monterey County) was affected by a previously unreported disease. Symptoms were observed on iceberg lettuce at the post-thin rosette stage (8 to 12 leaves). Plants were stunted and slightly chlorotic. Fine feeder roots had numerous, small (4 to 8 mm long), elongated, dark brown-to-black lesions. Larger secondary roots and taproots lacked lesions. No vascular discoloration was present. Isolations from root lesions consistently resulted in gray fungal colonies that formed catenulate, cylindrical, thin-walled, hyaline endoconidia and catenulate, subrectangular, thick-walled, dark aleuriospores. The fungus was identified as Thielaviopsis basicola (2). Conidial suspensions (5.0 × 105) of eight isolates from iceberg lettuce were used for pathogenicity tests. Iceberg cv. Ponderosa and romaine cv. Winchester were grown for 3 weeks in soilless peat moss rooting mix. Roots of 20 plants per cultivar were washed free of the rooting mix and soaked in conidial suspensions for 5 min. Plants were repotted and grown in a greenhouse. Control plant roots were soaked in sterile distilled water (SDW). After 3 weeks, inoculated iceberg exhibited slight chlorosis in comparison with control plants. Feeder roots of all iceberg plants inoculated with the eight isolates exhibited numerous black lesions and T. basicola was reisolated from these roots. Romaine lettuce, however, did not show any foliar symptoms. Small segments of roots had tan-to-light brown discoloration and T. basicola was occasionally reisolated (approximately 40% recovery). Roots of control iceberg and romaine showed no symptoms. Results were similar when this experiment was repeated. To explore the host range of T. basicola recovered from lettuce, two isolates were prepared and inoculated as described above onto 12 plants each of the following: iceberg lettuce (cv. Ponderosa), bean (cv. Blue Lake), broccoli (cv. Patriot), carrot (cv. Long Imperator #58), celery (cv. Conquistador), cotton (cv. Phy-72 Acala), cucumber (cv. Marketmore 76), green bunching onion (cv. Evergreen Bunching), parsley (cv. Moss Curled), pepper (cv. California Wonder 300 TMR), radish (cv. Champion), spinach (cvs. Bolero and Bossanova), and tomato (cv. Beefsteak). Control plant roots of all cultivars were soaked in SDW. After 4 weeks, only lettuce and bean roots had extensive brown-to-black lesions, from which the pathogen was consistently resiolated. Roots of cotton, pepper, spinach, and tomato had sections of light brown-to-orange discoloration; the pathogen was not consistently recovered from these sections. All other species and the control plants were symptomless. This experiment was repeated with similar results except that inoculated peppers were distinctly stunted compared with control plants. To my knowledge, this is the first report of black root rot caused by T. basicola on lettuce in California. Disease was limited to patches along edges of iceberg lettuce fields; disease incidence in these discrete patches reached as high as 35%. Affected plants continued to grow but remained stunted in relation to unaffected plants and were not harvested. Black root rot of lettuce has been reported in Australia (1); that report also showed that lettuce cultivars vary in susceptibility to T. basicola and isolates from lettuce were highly aggressive on bean but not on many other reported hosts of this pathogen. References: (1) R. G. O'Brien and R. D. Davis. Australas. Plant Pathol. 23:106, 1994. (2) C. V. Subramanian. No. 170 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1968.

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Synergistic Antifungal Activity of Graphene Oxide and Fungicides against Fusarium Head Blight In Vitro and In Vivo

Nanomaterials ◽

10.3390/nano11092393 ◽

2021 ◽

Vol 11 (9) ◽

pp. 2393

Author(s):

Xiuping Wang ◽

Fei Peng ◽

Caihong Cheng ◽

Lina Chen ◽

Xuejuan Shi ◽

...

Keyword(s):

Graphene Oxide ◽

Plant Pathogens ◽

Antimicrobial Agents ◽

Plant Protection ◽

Disease Incidence ◽

Agricultural Science ◽

Plant Diseases ◽

Synergistic Activity

Plant pathogens constantly develop resistance to antimicrobial agents, and this poses great challenges to plant protection. Therefore, there is a pressing need to search for new antimicrobials. The combined use of antimicrobial agents with different antifungal mechanisms has been recognized as a promising approach to manage plant diseases. Graphene oxide (GO) is a newly emerging and highly promising antimicrobial agent against various plant pathogens in agricultural science. In this study, the inhibitory activity of GO combined with fungicides (Mancozeb, Cyproconazol and Difenoconazole) against Fusarium graminearum was investigated in vivo and in vitro. The results revealed that the combination of GO and fungicides has significant synergistic inhibitory effects on the mycelial growth, mycelial biomass and spore germination of F. graminearum relative to single fungicides. The magnitude of synergy was found to depend on the ratio of GO and fungicide in the composite. In field tests, GO–fungicides could significantly reduce the disease incidence and disease severity, exhibiting a significantly improved control efficacy on F. graminearum. The strong synergistic activity of GO with existing fungicides demonstrates the great application potential of GO in pest management.

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Hevein-Like Antimicrobial Peptides Wamps: Structure–Function Relationship in Antifungal Activity and Sensitization of Plant Pathogenic Fungi to Tebuconazole by WAMP-2-Derived Peptides

International Journal of Molecular Sciences ◽

10.3390/ijms21217912 ◽

2020 ◽

Vol 21 (21) ◽

pp. 7912 ◽

Cited By ~ 3

Author(s):

Tatyana Odintsova ◽

Larisa Shcherbakova ◽

Marina Slezina ◽

Tatyana Pasechnik ◽

Bakhyt Kartabaeva ◽

...

Keyword(s):

Antifungal Activity ◽

Antimicrobial Peptides ◽

Structure Function ◽

Spore Germination ◽

Pathogenic Fungi ◽

Plant Pathogenic Fungi ◽

Fungal Cell ◽

Structure Function Relationship ◽

Function Relationship

Hevein-like antimicrobial peptides (AMPs) comprise a family of plant AMPs with antifungal activity, which harbor a chitin-binding site involved in interactions with chitin of fungal cell walls. However, the mode of action of hevein-like AMPs remains poorly understood. This work reports the structure–function relationship in WAMPs—hevein-like AMPs found in wheat (Triticum kiharae Dorof. et Migush.) and later in other Poaceae species. The effect of WAMP homologues differing at position 34 and the antifungal activity of peptide fragments derived from the central, N- and C-terminal regions of one of the WAMPs, namely WAMP-2, on spore germination of different plant pathogenic fungi were studied. Additionally, the ability of WAMP-2-derived peptides to potentiate the fungicidal effect of tebuconazole, one of the triazole fungicides, towards five cereal-damaging fungi was explored in vitro by co-application of WAMP-2 fragments with Folicur® EC 250 (25% tebuconazole). The antifungal activity of WAMP homologues and WAMP-2-derived peptides varied depending on the fungus, suggesting multiple modes of action for WAMPs against diverse pathogens. Folicur® combined with the WAMP-2 fragments inhibited the spore germination at a much greater level than the fungicide alone, and the type of interactions was either synergistic or additive, depending on the target fungus and concentration combinations of the compounds. The combinations, which resulted in synergism and drastically enhanced the sensitivity to tebuconazole, were revealed for all five fungi by a checkerboard assay. The ability to synergistically interact with a fungicide and exacerbate the sensitivity of plant pathogenic fungi to a commercial antifungal agent is a novel and previously uninvestigated property of hevein-like AMPs.

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