Stringent response mutants of Pseudomonas chlororaphis PA23 exhibit enhanced antifungal activity against Sclerotinia sclerotiorum in vitro

Sclerotinia sclerotiorum is a devastating necrotrophic pathogen that infects multiple crops, and its control is an unremitting challenge. In this work, we attempted to gain insights into the pivotal role of lipopeptides (LPs) in the antifungal activity of Bacillus amyloliquefaciens EZ1509. In a comparative study involving five Bacillus strains, B. amyloliquefaciens EZ1509 harboring four LPs biosynthetic genes (viz. surfactin, iturin, fengycin, and bacilysin) exhibited promising antifungal activity against S. sclerotiorum in a dual-culture assay. Our data demonstrated a remarkable upsurge in LPs biosynthetic gene expression through quantitative reverse transcription PCR during in vitro interaction assay with S. sclerotiorum. Maximum upregulation in LPs biosynthetic genes was observed on the second and third days of in vitro interaction, with iturin and fengycin being the highly expressed genes. Subsequently, Matrix-assisted laser desorption/ionization-time of flight-mass spectrometry analysis confirmed the presence of LPs in the inhibition zone. Scanning electron microscope analysis showed disintegration, shrinkage, plasmolysis, and breakdown of fungal hyphae. During in planta evaluation, S. sclerotiorum previously challenged with EZ1509 showed significant suppression in pathogenicity on detached leaves of tobacco and rapeseed. The oxalic acid synthesis was also significantly reduced in S. sclerotiorum previously confronted with antagonistic bacterium. The expression of major virulence genes of S. sclerotiorum, including endopolygalacturonase-3, oxalic acid hydrolase, and endopolygalacturonase-6, was significantly downregulated during in vitro confrontation with EZ1509.

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In vitro and in vivo antifungal activity of synthetic pure isothiocyanates against Sclerotinia sclerotiorum

Pest Management Science ◽

10.1002/ps.2126 ◽

2011 ◽

Vol 67 (7) ◽

pp. 869-875 ◽

Cited By ~ 29

Author(s):

Şener Kurt ◽

Ufuk Güneş ◽

Emine M Soylu

Keyword(s):

Antifungal Activity ◽

Sclerotinia Sclerotiorum ◽

In Vivo Antifungal Activity

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Antifungal activity of Pseudomonas chlororaphis Q16 against Sclerotinia sclerotiorum isolated from different medicinal plants

Zastita bilja ◽

10.5937/zasbilj1402056l ◽

2014 ◽

Vol 65 (2) ◽

pp. 56-63

Author(s):

Zorica Lepšanović ◽

Mira Starović ◽

Snežana Pavlović ◽

Dragana Jošić

Keyword(s):

Antifungal Activity ◽

Medicinal Plants ◽

Sclerotinia Sclerotiorum ◽

Pseudomonas Chlororaphis

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Comparison of the composition and fungicidal activity of essential oils from fennel fruits cultivated in Poland and Egypt

Polish Journal of Chemical Technology ◽

10.2478/pjct-2019-0018 ◽

2019 ◽

Vol 21 (2) ◽

pp. 38-42

Author(s):

Alicja Wodnicka ◽

Elżbieta Huzar ◽

Małgorzata Dzięcioł ◽

Maria Krawczyk

Keyword(s):

Antifungal Activity ◽

Essential Oil ◽

Essential Oils ◽

Sclerotinia Sclerotiorum ◽

Plant Material ◽

Fungicidal Activity ◽

Pathogenic Fungi ◽

Main Component ◽

Essential Oil Yield

Abstract The yield, composition and fungicidal activity of essential oils obtained from fennel fruits cultivated in Poland (FEOPOL) and Egypt (FEO-EG) were compared. The influence of the duration of hydrodistillation using a Clevenger apparatus on the essential oil yield was studied. The composition of the fennel essential oils was determined by GC-MS method. Studies have shown that FEO-POL and FEO-EG are two distinct chemotypes, which differ in yield and composition. The fennel fruits cultivated in Poland contained 4.14% of essential oil with trans-anethole as a main component. The plant material from Egypt was characterised by low content of essential oil (1.32%) with a predominant share of estragole. The fungicidal activity was tested in vitro against ten species of pathogenic fungi. The best result for FEO-POL was achieved against Sclerotinia sclerotiorum, Rhizoctonia solani and Botrytis cinerea. Antifungal activity of FEO-EG against tested fungi was weak or none.

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Antifungal activity and biological characteristics of the novel fungicide quinofumelin against Sclerotinia sclerotiorum

Plant Disease ◽

10.1094/pdis-08-20-1821-re ◽

2021 ◽

Author(s):

Xian Tao ◽

Huahua Zhao ◽

Haorong Xu ◽

Zhongke Li ◽

Jian-Xin Wang ◽

...

Keyword(s):

Antifungal Activity ◽

Sclerotinia Sclerotiorum ◽

Plant Pathogens ◽

Cross Resistance ◽

Broad Host Range ◽

In Planta ◽

Control Efficacy ◽

Worldwide Distribution ◽

Chemical Fungicides

Sclerotinia sclerotiorum is a devastating plant pathogen with a broad host range and worldwide distribution. The application of chemical fungicides is a primary strategy for controlling this pathogen. However, under the high selective pressure of chemical fungicides, fungicide resistance has emerged and gradually increased, resulting in the failure to control S. sclerotiorum in the field. Quinofumelin is a novel quinoline fungicide, but its antifungal activities against plant pathogens have been rarely reported. Here, we determined the antifungal activity of quinofumelin against S. sclerotiorum in vitro and in planta. The EC50 values ranged from 0.0004 to 0.0059 μg mL-1 with a mean EC50 of 0.0017 ± 0.0009 μg mL-1 and were normally distributed (P=0.402). In addition, no cross-resistance was observed between quinofumelin and other fungicides, dimethachlone, boscalid, or carbendazim, which are commonly used to manage S. sclerotiorum. Quinofumelin did not affect glycerol and oxalic acid production of either carbendazim-sensitive or -resistant isolates. Moreover, quinofumelin exhibited excellent protective, curative, and translaminar activity against S. sclerotiorum on oilseed rape leaves. Protective activity was higher than curative activity. Interestingly, quinofumelin inhibited the formation of the infection cushion in S. sclerotiorum, which may contribute to the control efficacy of quinofumelin against S. sclerotiorum in the field. Our findings indicate that quinofumelin has excellent control efficacy against S. sclerotiorum in vitro and in planta as compared with the currently extensively used fungicides and could be used to manage carbendazim- and dimethachlone-resistance in S. sclerotiorum in the field.

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Biocontrol by Phenazine-1-carboxamide-Producing Pseudomonas chlororaphis PCL1391 of Tomato Root Rot Caused by Fusarium oxysporum f. sp. radicis-lycopersici

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.1998.11.11.1069 ◽

1998 ◽

Vol 11 (11) ◽

pp. 1069-1077 ◽

Cited By ~ 235

Author(s):

Thomas F. C. Chin-A-Woeng ◽

Guido V. Bloemberg ◽

Arjan J. van der Bij ◽

Koen M. G. M. van der Drift ◽

Jan Schripsema ◽

...

Keyword(s):

Antifungal Activity ◽

Fusarium Oxysporum ◽

Root Rot ◽

Test System ◽

Pseudomonas Chlororaphis ◽

Tomato Root ◽

Hydrophobic Compound ◽

Biocontrol Activity ◽

In Vitro Antifungal Activity

Seventy bacterial isolates from the rhizosphere of tomato were screened for antagonistic activity against the tomato foot and root rot-causing fungal pathogen Fusarium oxysporum f. sp. radicis-lycopersici. One isolate, strain PCL1391, appeared to be an efficient colonizer of tomato roots and an excellent biocontrol strain in an F. oxysporum/tomato test system. Strain PCL1391 was identified as Pseudomonas chlororaphis and further characterization showed that it produces a broad spectrum of antifungal factors (AFFs), including a hydrophobic compound, hydrogen cyanide, chitinase(s), and protease(s). Through mass spectrometry and nuclear magnetic resonance, the hydrophobic compound was identified as phenazine-1-carboxamide (PCN). We have studied the production and action of this AFF both in vitro and in vivo. Using a PCL1391 transposon mutant, with a lux reporter gene inserted in the phenazine biosynthetic operon (phz), we showed that this phenazine biosynthetic mutant was substantially decreased in both in vitro antifungal activity and biocontrol activity. Moreover, with the same mutant it was shown that the phz biosynthetic operon is expressed in the tomato rhizosphere. Comparison of the biocontrol activity of the PCN-producing strain PCL1391 with those of phenazine-1-carboxylic acid (PCA)-producing strains P. fluorescens 2-79 and P. aureofaciens 30-84 showed that the PCN-producing strain is able to suppress disease in the tomato/F. oxysporum system, whereas the PCA-producing strains are not. Comparison of in vitro antifungal activity of PCN and PCA showed that the antifungal activity of PCN was at least 10 times higher at neutral pH, suggesting that this may contribute to the superior biocontrol performance of strain PCL1391 in the tomato/F. oxysporum system.

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Antifungal activity of plant essential oils and Pseudomonas chlororaphis strains against Cercospora beticola Sacc.

Zbornik Matice srpske za prirodne nauke ◽

10.2298/zmspn2140009s ◽

2021 ◽

pp. 9-19

Author(s):

Mira Starovic ◽

Danijela Ristic ◽

Snezana Pavlovic ◽

Mehmet Mozkan ◽

Dragana Josic

Keyword(s):

Antifungal Activity ◽

Essential Oils ◽

Leaf Spot ◽

Ocimum Basilicum ◽

Cercospora Beticola ◽

Pseudomonas Chlororaphis ◽

Myrtus Communis ◽

Origanum Vulgare ◽

Cell Free Supernatant

Leaf spot disease caused by Cercospora beticola Sacc. is the most destructive foliar disease of beet. Cercospora leaf spot is controlled primarily by fungicides because the non-chemical alternatives do not provide commercially viable control. One of the ways of reducing chemical application is the use of different essential oils (EOs) or antagonistic plant growth-promoting rhizobacteria (PGPB). This study evaluates several EOs and PGPB belonging to Pseudomonas chlororaphis as possible control agents of this pathogen. Antifungal properties were determined by in vitro microdilution method against five C. beticola monosporial isolates originated from the locality Brus, Serbia (53?53? N, 21?04?E and 429 m above sea level) using EOs from medicinal plants: Turkish pickling herb (Echinophora tenuifolia), oregano (Origanum vulgare), basil (Ocimum basilicum), and myrtle (Myrtus communis) obtained by a hydro-distillation method. All tested oils displayed some antifungal activity against the fungal isolates. Origanum vulgare EO demonstrated the strongest antifungal activity (MIC - 0.0055?0.0051mg/mL), Ocimum basilicum slightly lower (MIC - 0.075?0.045mg/mL), followed by Myrtus communis (MIC - 0.775?0.045 mg/ mL) and Echinophora tenuifolia (MIC - 7.75?4.5 mg/mL). Five tested P. chlororaphis strains exhibited some antagonistic effect against C. beticola. Overnight culture (ONC) of P. chlororaphis strain E65 induced the highest percentage of inhibition (75.8%), followed by N3 (72.0%). A cell-free supernatant (CFS) and the CFS treated with EDTA (CFS-EDTA) of these strains showed similar inhibition of 60.2 and 56.0%, and both strains suppressed C. beticola growth. P. chlororaphis strains M1 and K113 also reduced the fungal growth by 67-70% using ONC and between 48-57% using different CFS fractions. The strains L1 and B25 caused inhibition of 60% using ONC and 50% by CFS. The lowest inhibition (~40%) by CFS-EDTA and heat-treated cell-free supernatant (HT-CFS) was recorded for B25, which was used as a reference strain. The tested isolates of C. beticola were susceptible to all selected essential oils and P. chlororaphis strains E25, N3, M1, and K113 in vitro, making them a promising non-chemical control agent. It is recommended that these findings should be tested in field conditions.

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Inhibition of the Growth and Development of Sclerotinia sclerotiorum (Lib.) De Bary by Combining Azoxystrobin, Penicillium chrysogenum VKM F-4876d, and Bacillus Strains

Agronomy ◽

10.3390/agronomy11122520 ◽

2021 ◽

Vol 11 (12) ◽

pp. 2520

Author(s):

Vera V. Yaderets ◽

Nataliya V. Karpova ◽

Elena V. Glagoleva ◽

Alexander I. Ovchinnikov ◽

Kseniya S. Petrova ◽

...

Keyword(s):

Antifungal Activity ◽

Sclerotinia Sclerotiorum ◽

Plant Pathogen ◽

Penicillium Chrysogenum ◽

Growth And Development ◽

Crop Protection ◽

Pathogenic Fungi ◽

Fungal Cell ◽

Bacillus Strains

Sclerotinia sclerotiorum (Lib.) de Bary is a plant pathogen with a wide host range, which causes significant yield and storage losses of edible roots and other plant products. Due to its ability to sclerotia formation, the efficient control of this pathogen is complicated. The study of five Bacillus strains (B. subtilis VKM B-3154D, VKM B-3155D, VKM B-3505D, VKM B-2998D, and B. amyloliquefaciens VKM B-3153D) showed their ability to produce polyene antibiotics suppressing the growth and development of plant pathogenic fungi. The maximum concentration of polyene compounds was revealed for B. subtilis VKM B-2998D. A high in vitro antifungal activity of a dry mycelium biomass (DMP) of Penicillium chrysogenum VKM F-4876D, B. subtilis VKM B-2998D, and their combination has been demonstrated in relation to S. sclerotiorum. A combined application of DMP (0.3 g/L) and azoxystrobin at low dosage (2.5 mg/L) showed a high suppressing activity towards S. sclerotiorum (100% growth inhibition) including inhibition of a sclerotia formation that may be useful for the development of efficient methods of crop protection against this plant pathogen. A high performance liquid chromatography (HPLC) analysis of DMP revealed the presence of mevastatin suggesting the mechanism of the DMP antifungal activity is based on the blocking of the ergosterol (the main component of fungal cell walls) biosynthesis. The results of the study provide a prerequisite to the development of biopreparations to control S. sclerotiorum, whose use may provide a reduction of concentrations of fungicides used in agriculture and the corresponding reduction of their negative xenobiotic impact on the environment and recovery of the ecological balance in the soil.

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