scholarly journals In vitro evaluation of fungal antagonists of Phytophthora nicotianae

2017 ◽  
Vol 38 (SI 2 - 6th Conf EFPP 2002) ◽  
pp. 634-637
Author(s):  
R. Nicoletti ◽  
F. Raimo ◽  
E. Cozzolino
Keyword(s):  
Mycelial Growth ◽  
Central Italy ◽  
Phytophthora Nicotianae ◽  
Aspergillus Sydowii ◽  
Black Shank ◽  
Culture Filtrates ◽  
Dual Cultures ◽  
Penicillium Brevicompactum ◽  
Fusarium Chlamydosporum

As tobacco black shank epidemics caused by Phytophthora nicotianae occurred in central Italy in the late 1990s, fungal antagonists of the pathogen were searched in the rhizosphere of tobacco plants. Isolates of Aspergillus sydowii, Fusarium chlamydosporum, Gliocladium roseum, Penicillium brevicompactum, P. chrysogenum, Scopulariopsis candida and Trichoderma harzianum were recovered. Antagonism of these isolates toward P. nicotianae was evaluated in vitro: even if no hyphal interactions were observed in dual cultures, aberration in mycelial growth and morphology of sporangia occurred in most cases. Unlike those of T. harzianum, concentrated culture filtrates of A. sydowii, F. chlamydosporum, G. roseum, P. brevicompactum, P. chrysogenum, inhibited growth of all P. nicotianae isolates tested, while culture filtrates of S. candida caused aberrant mycelial growth.

scholarly journals Sensitivity of Phytophthora nicotianae From Tobacco to Fluopicolide, Mandipropamid, and Oxathiapiprolin

Plant Disease ◽  
2016 ◽  
Vol 100 (10) ◽  
pp. 2119-2125 ◽  
Author(s):  
Tianli Qu ◽  
Yuanyuan Shao ◽  
Alexander S. Csinos ◽  
Pingsheng Ji
Keyword(s):  
Mycelial Growth ◽  
Agar Medium ◽  
Phytophthora Nicotianae ◽  
Limited Information ◽  
Growth Reduction ◽  
Pathogen Population ◽  
Baseline Sensitivity ◽  
Resistance Development ◽  
Black Shank

Black shank incited by Phytophthora nicotianae is a devastating disease in the production of tobacco. Fungicides have been commonly used for managing the disease; however, there is only a narrow pool of effective fungicides. A few new fungicides became available in recent years, including fluopicolide, mandipropamid, and oxathiapiprolin, which reduced diseases incited by oomycetes under field conditions. Limited information is available regarding sensitivity of P. nicotianae isolates to these new fungicides. Research was conducted to determine effects of the three new fungicides on P. nicotianae isolates from tobacco in Georgia. Studies with 106 isolates indicated that they did not grow when agar medium was amended with the fungicides at the rate of 1 μg/ml. Twenty isolates were used for in vitro studies to determine sensitivity to the fungicides. Fluopicolide, mandipropamid, and oxathiapiprolin inhibited mycelial growth of the isolates with mean EC50 values (effective concentrations that provide 50% growth reduction) of 0.09, 0.04, and 0.001 μg/ml, respectively. EC50 values of fluopicolide, mandipropamid, and oxathiapiprolin for inhibiting sporangial formation were 0.15, 0.03, and 0.0002 μg/ml, respectively. EC50 values for suppressing zoospore germination averaged 0.16, 0.04, and 0.002 μg/ml for fluopicolide, mandipropamid, and oxathiapiprolin, respectively. Results from the study indicated that P. nicotianae isolates from tobacco in Georgia were sensitive to the fungicides, with lower EC50 for oxathiapiprolin than for fluopicolide and mandipropamid. The information on effectiveness and baseline sensitivity of fungicides on P. nicotianae will facilitate monitoring of resistance development in the pathogen population.

scholarly journals Diffusible Compounds Produced by Hanseniaspora osmophila and Gluconobacter cerinus Help to Control the Causal Agents of Gray Rot and Summer Bunch Rot of Table Grapes

Antibiotics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 664
Author(s):  
Matías Olivera ◽  
Ninoska Delgado ◽  
Fabiola Cádiz ◽  
Natalia Riquelme ◽  
Iván Montenegro ◽  
...  
Keyword(s):  
Mycelial Growth ◽  
Inhibitory Effect ◽  
Biocontrol Agents ◽  
Environmental Cost ◽  
Antifungal Compounds ◽  
Table Grapes ◽  
Dual Cultures ◽  
Bunch Rot ◽  
Direct Bioautography

Gray and summer bunch rot are important diseases of table grapes due to the high economic and environmental cost of their control with synthetic fungicides. The ability to produce antifungal compounds against the causal agents Botrytis, Aspergillus, Penicillium, and Rhizopus of two microorganisms isolated from table grapes and identified as Hanseniaspora osmophila and Gluconobacter cerinus was evaluated. In dual cultures, both biocontrol agents (together and separately) inhibited in vitro mycelial growth of these pathogens. To identify the compounds responsible for the inhibitory effect, extractions were carried out with organic solvents from biocontrol agents separately. Through dual cultures with pathogens and pure extracts, only the hexane extract from H. osmophila showed an inhibitory effect against Botrytis cinerea. To further identify these compounds, the direct bioautography technique was used. This technique made it possible to determine the band displaying antifungal activity at Rf = 0.05–0.2. The compounds present in this band were identified by GC-MS and compared to the NIST library. The most abundant compounds, not previously reported, corresponded to alkanes, ketones, alcohols, and terpenoids. H. osmophila and G. cerinus have the potential to control the causal agents of gray and summer bunch rot of table grapes.

scholarly journals The Tobacco Trichome Exudate Z-abienol and Its Relationship With Plant Resistance to Phytophthora nicotianae

Plant Disease ◽  
2017 ◽  
Vol 101 (7) ◽  
pp. 1214-1221 ◽  
Author(s):  
William T. Steede ◽  
Justin M. Ma ◽  
David P. Eickholt ◽  
Katherine E. Drake-Stowe ◽  
Sheri P. Kernodle ◽  
...  
Keyword(s):  
Close Association ◽  
Hyphal Growth ◽  
Field Resistance ◽  
Phytophthora Nicotianae ◽  
In Vitro Assays ◽  
Black Shank ◽  
Plant Parts ◽  
Tobacco Cultivar ◽  
High Level

In previous research, we discovered a favorable quantitative trait locus (QTL) in cigar tobacco cultivar ‘Beinhart 1000’ designated as Phn15.1, which provides a high level of partial resistance to the black shank disease caused by Phytophthora nicotianae. A very close genetic association was also found between Phn15.1 and the ability to biosynthesize Z-abienol, a labdanoid diterpene exuded by the trichomes onto above-ground plant parts, and that imparts flavor and aroma characteristics to Oriental and some cigar tobacco types. Because accumulation of Z-abienol is considered to be undesirable for cultivars of other tobacco types, we herein describe a series of experiments to gain insight on whether this close association is due to genetic linkage or pleiotropy. First, in an in vitro bioassay, we observed Z-abienol and related diterpenes to inhibit hyphal growth of P. nicotianae at concentrations between 0.01 and 100 ppm. Secondly, we field-tested transgenic versions of Beinhart 1000 carrying RNAi constructs for downregulating NtCPS2 or NtABS, two genes involved in the biosynthesis of Z-abienol. Thirdly, we also field tested a recombinant inbred line population segregating for a truncation mutation in NtCPS2 leading to an interrupted Z-abienol pathway. We observed no correlation between field resistance to P. nicotianae and the ability to accumulate Z-abienol in either the transgenic materials or the mapping population. Results suggest that, although Z-abienol may affect P. nicotianae when applied at high concentrations in in vitro assays, the compound has little effect on black shank disease development under natural field conditions. Thus, it should be possible to disassociate Phn15.1-mediated black shank resistance identified in cigar tobacco cultivar Beinhart 1000 from the ability to accumulate Z-abienol, an undesirable secondary metabolite for burley and flue-cured tobacco cultivars.

scholarly journals In vitro antifungal activity of endophytic bacteria isolated from date palm (Phoenix doctylifera L.) against fungal pathogens causing leaf spot of date palm

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
H. H. Al-Nadabi ◽  
N. S. Al-Buraiki ◽  
A. A. Al-Nabhani ◽  
S. N. Maharachchikumbura ◽  
R. Velazhahan ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Endophytic Bacteria ◽  
Mycelial Growth ◽  
Fungal Pathogens ◽  
Date Palm ◽  
Dual Culture ◽  
Bacterial Endophytes ◽  
Bacterial Strains ◽  
Culture Filtrates

Abstract Background Date palm ((Phoenix doctylifera L.) suffers from several fungal diseases. The endophytic microorganisms present in higher plants generally offer protection to their host plants against invading phytopathogenic fungi and bacteria. In the present study, endophytic bacteria associated with date palm leaves were isolated and their in vitro antagonistic potential against fungal pathogens causing leaf spots in date palm was demonstrated. Results Endophytic bacteria were isolated from date palm leaves of 3 different cultivars viz., Nighal, Khalas and Khinaizi and evaluated for their inhibitory activity against leaf spot pathogens of date palm viz., Fusarium solani, Alternaria sp., Nigrospora sp., Thieloviopsis sp., Curvularia subpapendrofii and Tilletiopsis minor using an in vitro dual culture assay. Of the 24 endophytic bacterial strains tested, the endophytes designated B1, B7, B8 and B9 obtained from cv. Nighal showed inhibitory activities (more than 55% mycelial growth inhibition) against F. solani and Alternaria sp. None of the bacterial endophytes inhibited the growth of other fungal pathogens tested. These antagonistic bacterial strains were identified as Pantoea septica on the basis of 16S rRNA gene sequence analysis. The hyphae of F. solani and Alternaria sp. exhibited morphological abnormalities such as shrinkage and disintegration when grown in the presence of antagonistic bacterial endophytes. The cell-free culture filtrates of the bacterial endophytes caused inhibition of mycelial growth and induced leakage of electrolytes from the mycelia of F. solani and Alternaria sp. This is the first study that describes inhibition of the date palm pathogens F. solani and Alternaria sp. by P. septica. Conclusion Endophytic Pantoea septica strains isolated from date palm leaves inhibited the mycelial growth of F. solani and Alternaria sp. and induced morphological changes in their mycelia. The culture filtrates of these bacterial strains also inhibited the mycelial growth and caused leakage of electrolytes from the mycelia of F. solani and Alternaria sp. These promising bacterial strains can be exploited as biocontrol agents to control F. solani and Alternaria sp.-induced leaf spot diseases of date palm.

scholarly journals Biocontrol of PGPR strain Bacillus amyloliquefaciens Ba168 against Phytophthora nicotianae on tobacco

2019 ◽  
Author(s):  
Dongsheng Guo ◽  
Chenhong Yuan ◽  
Yunyan Luo ◽  
YaHan Chen ◽  
Meihuan Lu ◽  
...  
Keyword(s):  
Crude Extract ◽  
Dry Weight ◽  
Plant Growth Promoting Rhizobacteria ◽  
Sem Analysis ◽  
Phytophthora Nicotianae ◽  
Black Shank ◽  
Biocontrol Efficacy ◽  
Plant Growth Promoting ◽  
Pgpr Strain

AbstractTobacco black shank (TBS) caused by Phytophthora nicotianae is destructive to almost all kinds of tobacco cultivars and is widespread in many tobacco-planted countries. Here, an isolated plant growth-promoting rhizobacteria (PGPR) strain Ba168 is promise in biocontrol of TBS. In vitro assays disclosed a strong P. nicotianae suppression activity and the field utilization potential (FUP) by characterized the crude extract of culture filtrates of Ba168. P. nicotianae’s growth was inhibited by the crude extract at minimum inhibitory concentration (MIC) of 5μl/mL. Extracellular conductivity, pH and the wet, dry weight of P. nicotianae’s mycelia, were significantly different after treated with different concentrations of the crude extract and the deformity and perforation of treated P. nicotianae’s hyphae can be observed in scanning electron microscope (SEM) analysis. Proteome characterizations of the crude extract were used as supplementary proofs that further evaluated FUP of Ba168. We then identified strain Ba168 as B. amyloliquefaciens by its genetic and phenotypic characteristics. Field assays comparatively evaluated TBS control efficacy of these PGPRs and agrochemicals. Pooling analysis of the results showed that the biocontrol efficacy of Ba168 preparation is only lower than Mixture of Propamocarb hydrochloride and Azoxystrobin (MPA) but better than other tested subjects. Although the existence of differences in biocontrol efficacy, PGPR preparations effectively reduced the disease index of tobacco.ImportanceThis work demonstrates the promising biocontrol potential of B. amyloliquefaciens Ba168 and highlights the positive roles of PGPR in suppression of this soil-borne disease.

scholarly journals   Testing of Algerian fir zygotic and somatic embryos on defence reactions in vitro

2012 ◽  
Vol 58 (No. 2) ◽  
pp. 84-90
Author(s):  
B. Vooková ◽  
J. Hřib ◽  
V. Adamec
Keyword(s):  
Somatic Embryos ◽  
Mycelial Growth ◽  
Zygotic Embryos ◽  
Dual Cultures ◽  
Defence Reactions ◽  
Algerian Fir

Defence reactions of desiccated cotyledonary somatic embryos and mature zygotic embryos of Abies numidica were tested by dual cultures with tester, fungus Phaeolus schweinitzii. Both types of embryos expressed defence reactions. Mutual comparisons of zygotic and somatic embryos showed important differences between defence reactions against mycelial growth towards these embryos. Greater defence reactions were observed in zygotic embryos relative to defence found in somatic embryos.  

In vitro and in vivo activities of eugenol against tobacco black shank caused by Phytophthora nicotianae

2017 ◽  
Vol 142 ◽  
pp. 148-154 ◽  
Author(s):  
Changliang Jing ◽  
Jianyu Gou ◽  
Xiaobin Han ◽  
Qian Wu ◽  
Chengsheng Zhang
Keyword(s):  
Phytophthora Nicotianae ◽  
Black Shank ◽  
Tobacco Black Shank

scholarly journals In-vitro Evaluation of Botanicals, Fungi-toxic Chemicals and Bio-control Agent for Efficacy against Turcicum Leaf Blight of Maize

2019 ◽  
Vol 5 ◽  
pp. 73-80
Author(s):  
Subash Subedi ◽  
Saraswati Neupane ◽  
Surendra BK ◽  
Lokendra Oli
Keyword(s):  
Growth Inhibition ◽  
Mycelial Growth ◽  
Trichoderma Viride ◽  
Control Agent ◽  
Leaf Blight ◽  
Acorus Calamus ◽  
Exserohilum Turcicum ◽  
Fungicidal Action ◽  
Dual Cultures

Maize is the second most important cereal crop of Nepal. Its growth and production is severely affected by Turcicum leaf blight caused by Exserohilum turcicum at pre-harvest stage. A total of 6 botanicals, 4 chemical fungicides and 1 bio-control agent were evaluated for efficacy against Exserohilum turcicum under in vitro conditions following poisoned food technique at National Maize Research Program, Rampur, Nepal. The experiment was carried out in a completely randomized design with 5 replications. All the tested botanicals, fungicides and bio-control agent exhibited fungicidal action and significantly inhibited mycelial growth of the test pathogen over untreated control. Among botanicals, extract of Acorus calamus L. at 1% W/V checked the pathogen growth completely in-vitro. The mycelial growth inhibition percent of Artimisia indica Willd, Lantana camera L., Allium sativum L., Xanthoxylum armatum DC., and Azadirachta indica A. Juss. at the concentration of 2.5% W/V on PDA was 75.18%, 74.00%, 44.68%, 44.21% and 37.59% respectively. Among fungicides, the mycelial growth inhibition percent of E. turcicum due to ACME-COP (Copper oxychloride 50% WP), SAAF (Carbendazim 12% + Mancozeb 63% WP), Dithane M-45 (Mancozeb 75% WP) and Bavistin (Carbendazim 50% WP) at the concentration of 1000 ppm on PDA was 70.69%, 68.44%, 61.23%, and 60.52% respectively. Antagonist Trichoderma viride developed more rapidly than E. turcium in single as well as in dual cultures. T. viride caused significantly inhibition of 35% of the pathogen E. turcicum on the 5th day of incubation. These results have important implications for the management of turcicum leaf blight disease in maize.

Influences of Culture Media, Temperature and Light/Dark Conditions on Growth and Antifungal Activity of Streptomyces spp. Against Botrytis cinerea, in vitro and on Tomato Leaf

2021 ◽  
Author(s):  
Sawai Boukaew ◽  
Siriporn Yossan ◽  
Benjamas Cheirsilp ◽  
Wanida Petlamul ◽  
Poonsuk Prasertsan
Keyword(s):  
Antifungal Activity ◽  
Botrytis Cinerea ◽  
Mycelial Growth ◽  
Culture Media ◽  
Tomato Leaf ◽  
Antifungal Compounds ◽  
Streptomyces Spp ◽  
Culture Filtrates ◽  
Dark Conditions

Abstract The influences of culture media, temperature, and light/dark conditions on growth and antifungal activity of the three strains Streptomyces spp. against Botrytis cinerea was studied. Results of in vitro study indicated that the GYM agar and incubated at 28°C exhibited good mycelial growth and a spore mass production of the three strains of Streptomyces spp. On the other hand, the PDA and incubation at 21°C were suitable for the mycelial growth of B. cinerea . Moreover, light/dark conditions had an effect on the growth of the two strains of S. philanthi . The strains RL-1-178 and RM-1-138 of S. philanthi grown in all media and incubation temperatures tested possessed antifungal activity against B. cinerea (100% inhibition) while S. mycarofaciens showed different results on PDA (83% inhibition) and GYM (88% inhibition) with the optimum incubation temperature at 21°C. Then, the antifungal compounds in culture filtrates produced by the three antagonistic strains against B. cinerea were tested on tomato leaf. They showed a significantly higher inhibitory effect on the symptoms of blight disease on tomato leaf compared with the control. The better protection efficacy against B. cinerea on tomato leaf was observed with the culture filtrates of S. philanthi RM-1-138 (82.89% and 0.33 cm 2 lesion areas symptoms). Moreover, the antifungal compounds in the culture filtrate of S. philanthi RM-1-138, identified by GC-MS, were greatly altered relative to concentration components under different temperatures and light/dark conditions tested. Our results clearly demonstrated that the environmental factors have an influence on antifungal activity of the three strains of Streptomyces spp.

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