Effectiveness of Dunaliella salina Extracts against Bacillus subtilis and Bacterial Plant Pathogens

Several bacteria pathogens are responsible for plant diseases causing significant economic losses. The antibacterial activity of Dunaliella salina microalgae extracts were investigated in vitro and in vivo. First, biomass composition was chemically characterized and subjected to extraction using polar/non-polar solvents. The highest extraction yield was obtained using chloroform:methanol (1:1 v/v) equal to 170 mg g−1 followed by ethanol (88 mg g−1) and hexane (61 mg g−1). In vitro examination of hexane extracts of Dunaliella salina demonstrated antibacterial activity against all tested bacteria. The hexane extract showed the highest amount of β-carotene with respect to the others, so it was selected for subsequent analyses. In vivo studies were also carried out using hexane extracts of D. salina against Pseudomonas syringae pv. tomato and Pectobacterium carotovorum subsp. carotovorum on young tomato plants and fruits of tomato and zucchini, respectively. The treated young tomato plants exhibited a reduction of 65.7% incidence and 77.0% severity of bacterial speck spot disease. Similarly, a reduction of soft rot symptoms was observed in treated tomato and zucchini fruits with a disease incidence of 5.3% and 12.6% with respect to 90.6% and 100%, respectively, for the positive control.

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Expression of a Synthesized Gene Encoding Cationic Peptide Cecropin B in Transgenic Tomato Plants Protects against Bacterial Diseases

Applied and Environmental Microbiology ◽

10.1128/aem.00698-09 ◽

2009 ◽

Vol 76 (3) ◽

pp. 769-775 ◽

Cited By ~ 55

Author(s):

Pey-Shynan Jan ◽

Hsu-Yuang Huang ◽

Hueih-Min Chen

Keyword(s):

Xanthomonas Campestris ◽

Plant Pathogens ◽

Transgenic Tomato ◽

Plant Diseases ◽

Gene Encoding ◽

Tomato Plants ◽

Cecropin B ◽

Transgenic Tomato Plants

ABSTRACT The cationic lytic peptide cecropin B (CB), isolated from the giant silk moth (Hyalophora cecropia), has been shown to effectively eliminate Gram-negative and some Gram-positive bacteria. In this study, the effects of chemically synthesized CB on plant pathogens were investigated. The S50s (the peptide concentrations causing 50% survival of a pathogenic bacterium) of CB against two major pathogens of the tomato, Ralstonia solanacearum and Xanthomonas campestris pv. vesicatoria, were 529.6 μg/ml and 0.29 μg/ml, respectively. The CB gene was then fused to the secretory signal peptide (sp) sequence from the barley α-amylase gene, and the new construct, pBI121-spCB, was used for the transformation of tomato plants. Integration of the CB gene into the tomato genome was confirmed by PCR, and its expression was confirmed by Western blot analyses. In vivo studies of the transgenic tomato plant demonstrated significant resistance to bacterial wilt and bacterial spot. The levels of CB expressed in transgenic tomato plants (∼0.05 μg in 50 mg of leaves) were far lower than the S50 determined in vitro. CB transgenic tomatoes could therefore be a new mode of bioprotection against these two plant diseases with significant agricultural applications.

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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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Plant Extract Treatments Induce Resistance to Bacterial Spot by Tomato Plants for a Sustainable System

Horticulturae ◽

10.3390/horticulturae6020036 ◽

2020 ◽

Vol 6 (2) ◽

pp. 36

Author(s):

Kamal A. M. Abo-Elyousr ◽

Najeeb M. Almasoudi ◽

Ahmed W. M. Abdelmagid ◽

Sergio R. Roberto ◽

Khamis Youssef

Keyword(s):

Antibacterial Activity ◽

Plant Extracts ◽

Integrated Management ◽

Nerium Oleander ◽

Bacterial Spot ◽

Tomato Plants ◽

Sustainable System ◽

Pathogen Populations

The aim of this study is to assess the effect of extracts of Nerium oleander, Eucalyptus chamadulonsis and Citrullus colocynthis against bacterial spot disease of tomato and to investigate the induction of resistance by tomato (Solanum lycopersicum) in order to promote a sustainable management system. The antibacterial activity of aqueous and ethanol plant extracts was tested against Xanthomonas axonopodis pv. vesicatoria, isolate PHYXV3, in vitro and in vivo. The highest antibacterial activity in vitro was obtained with C. colocynthis, N. oleander and E. chamadulonsis, respectively. In vivo, ethanol extracts of N. oleander and E. chamadulonsis were more effective than aqueous extracts in reducing pathogen populations on tomato leaves. Under greenhouse conditions, application of the plant extracts at 15% (v/v) to tomato plants significantly reduced disease severity and increased the shoot weight of ‘Super Marmande’ tomato. In most cases, plant extracts significantly increased total phenol and salicylic acid content of tomato plants compared to either healthy or infected ones. In addition, C. colocynthis and E. chamadulonsis extracts significantly increased peroxidase activity while only E. chamadulonsis increased polyphenol oxidase after infection with the causal agent. The results indicated that the plant extracts showed promising antibacterial activity and could be considered an effective tool in integrated management programs for a sustainable system of tomato bacterial spot control.

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Biocontrol of Tomato Fusarium wilt by Trichoderma Species under in vitro and in vivo Conditions

Cercetari Agronomice in Moldova ◽

10.1515/cerce-2016-0008 ◽

2016 ◽

Vol 49 (1) ◽

pp. 91-98 ◽

Cited By ~ 6

Author(s):

H. Barari

Keyword(s):

Plant Protection ◽

Disease Incidence ◽

Plant Diseases ◽

Growth And Yield ◽

Mazandaran Province ◽

Trichoderma Species ◽

Tomato Plants ◽

Geographical Regions

AbstractTrichodermaspp. have long been used as biological control agents against plant fungal diseases, but the mechanisms by which the fungi confer protection are not well understood. Our goal in this study was to isolate species ofTrichoderma, that exhibit high levels of biocontrol efficacy from natural environments and to investigate the mechanisms by which these strains confer plant protection. In this study, efficacy of the native isolates ofTrichodermaspecies to promote the growth and yield parameters of tomato and to manageFusariumwilt disease underin vitroandin vivoconditions were investigated. The dominant pathogen, which causesFusariumwilt of tomato, was isolated and identified asFusarium oxysporumf. sp.lycopersici(FOL). Twenty eight nativeTrichodermaantagonists were isolated from healthy tomato rhizosphere soil in different geographical regions of Mazandaran province, Iran. Underin vitroconditions, the results revealed thatTrichoderma harzianum, isolate N-8, was found to inhibit effectively the radial mycelial growth of the pathogen (by 68.22%). Under greenhouse conditions, the application ofT. harzianum(N-8) exhibited the least disease incidence (by 14.75%). Also, tomato plants treated withT. harzianum(N-8) isolate showed a significant stimulatory effect on plant height (by 70.13 cm) and the dry weight (by 265.42 g) of tomato plants, in comparison to untreated control (54.6 cm and 195.5 g). Therefore, the antagonistT. harzianum(N-8) is chosen to be the most promising bio-control agent forF. oxysporumf. sp.lycopersici. On the base of present study, the biocontrol agents of plant diseases might be exploited for sustainable disease management programs to save environmental risk.

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Antibacterial activity of tannins towards Pseudomonas syringae pv. tomato, and their potential as biostimulants on tomato plants

Phytopathologia Mediterranea ◽

10.36253/phyto-11732 ◽

2021 ◽

Vol 60 (1) ◽

pp. 23-36

Author(s):

Paolo CANZONIERE ◽

Sara FRANCESCONI ◽

Samuele GIOVANDO ◽

Giorgio BALESTRA

Keyword(s):

Antibacterial Activity ◽

Water Treatment ◽

Pseudomonas Syringae ◽

Crop Protection ◽

Dry Weight ◽

Economic Losses ◽

Copper Hydroxide ◽

Copper Treatment

Pseudomonas syringae pv. tomato (Pst), the causal agent of bacterial speck of tomato, is a significant cause of economic losses in tomato crops. This disease is mainly controlled with preventive use of cupric salt formulations. Antibacterial activity of the tannins U1, U2, U3 and U4, applied alone at 1% w/v concentration or in combination with half (0.045% w/v) of standard of copper hydroxide treatments, was assayed for effects on Pst. In vitro, the four tannins completely inhibited Pst colony formation after 24 h, but U2 (quebracho tannins) + ½ Cu(OH)2 allowed Pst growth after 48 h of incubation, indicating that, since U2 is composed of high molecular condensed tannins it is likely that their structures have chelated the copper hydroxide much more then hydrolysable ones, thus inactivating copper hydroxide and tannins. In fact, this activity of the tannins was equivalent to that for 0.045% w/v of copper hydroxide. Effects of tannins on tomato plant growth were also assessed. On seedlings, long-term U1 treatments increased dry weight of shoots compared to copper hydroxide, but not to water treatment. The U4 treatment increased the NBI values compared to copper treatment but did not show significant differences compared to the water treatment. Inhibitory activity of tannin treatments reduced disease by 37–62%, and 60% after copper treatment, while disease severity was reduced by 33–54% after treating plants with tannins and 36% after copper treatment. On mature plants treated once, the disease reduction was 27–39% after tannin treatments and 44% after copper treatment, while severity was reduced by 50–60% from tannin treatments, and 47% by copper. In seedlings and mature plants, these reductions were similar (P > 0.05) for the tannins and copper treatments. This study indicates a novel crop protection strategy using natural products as alternatives to xenobiotic compounds.

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Tetrandrine, a potent antifungal agent: inhibits mycelial growth and virulence of Botrytis cinerea

Phytopathology ◽

10.1094/phyto-10-20-0446-r ◽

2020 ◽

Author(s):

Pingliang Li ◽

jian zou ◽

Yanhan Dong ◽

jintao Jiang ◽

Wenxing Liang ◽

...

Keyword(s):

Botrytis Cinerea ◽

Antifungal Agent ◽

Plant Pathogens ◽

Efflux Pump ◽

Hyphal Growth ◽

Tomato Plants ◽

Low Concentrations ◽

Grey Mold

Tetrandrine (TET) is a potent calcium channel blocker used for the treatment of hypertension and inflammation. Currently, TET is predominantly used to treat a variety of human diseases, and there is little information regarding the use of TET against plant pathogens. In this study, we explored the antifungal activity of TET on a plant pathogen, Botrytis cinerea. We show that administration of low concentrations of TET effectively inhibited hyphal growth of fungus grown on potato dextrose agarose, and decreased the virulence of B. cinerea in tomato plants. Real-time PCR revealed that the expression of drug efflux pump related genes (alcohol dehydrogenase 1, multi-drug/pheromone exporter, pleiotropic drug resistance protein 1, and synaptic vesicle transporter) were down-regulated in the presence of TET. Finally, we show that TET acts synergistically with iprodione, resulting in increased inhibition of B. cinerea both in vitro and in vivo. These results indicate that TET might act as an effective antifungal agent in reducing grey mold disease.

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Inhibition of Fungal and Bacterial Plant Pathogens In Vitro and In Planta with Ultrashort Cationic Lipopeptides

Applied and Environmental Microbiology ◽

10.1128/aem.01334-07 ◽

2007 ◽

Vol 73 (20) ◽

pp. 6629-6636 ◽

Cited By ~ 68

Author(s):

Arik Makovitzki ◽

Ada Viterbo ◽

Yariv Brotman ◽

Ilan Chet ◽

Yechiel Shai

Keyword(s):

Pseudomonas Syringae ◽

Pathogenic Bacteria ◽

Plant Pathogens ◽

Antimicrobial Agents ◽

Plant Protection ◽

Microscopic Analysis ◽

Plant Diseases ◽

In Planta ◽

Global Food Security

ABSTRACT Plant diseases constitute an emerging threat to global food security. Many of the currently available antimicrobial agents for agriculture are highly toxic and nonbiodegradable and cause extended environmental pollution. Moreover, an increasing number of phytopathogens develop resistance to them. Recently, we have reported on a new family of ultrashort antimicrobial lipopeptides which are composed of only four amino acids linked to fatty acids (A. Makovitzki, D. Avrahami, and Y. Shai, Proc. Natl. Acad. Sci. USA 103:15997-16002, 2006). Here, we investigated the activities in vitro and in planta and the modes of action of these short lipopeptides against plant-pathogenic bacteria and fungi. They act rapidly, at low micromolar concentrations, on the membranes of the microorganisms via a lytic mechanism. In vitro microscopic analysis revealed wide-scale damage to the microorganism's membrane, in addition to inhibition of pathogen growth. In planta potent antifungal activity was demonstrated on cucumber fruits and leaves infected with the pathogen Botrytis cinerea as well as on corn leaves infected with Cochliobolus heterostrophus. Similarly, treatment with the lipopeptides of Arabidopsis leaves infected with the bacterial leaf pathogen Pseudomonas syringae efficiently and rapidly reduced the number of bacteria. Importantly, in contrast to what occurred with many native lipopeptides, no toxicity was observed on the plant tissues. These data suggest that the ultrashort lipopeptides could serve as native-like antimicrobial agents economically feasible for use in plant protection.

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Characterization of Pseudomonas syringae pv. syringae from Diseased Stone Fruits in Kyrgyzstan and Testing of Biological Agents against Pathogen

International Journal of Phytopathology ◽

10.33687/phytopath.009.02.3270 ◽

2020 ◽

Vol 9 (2) ◽

pp. 71-91

Author(s):

Tinatin Doolotkeldieva ◽

Saikal Bobusheva

Keyword(s):

Pseudomonas Syringae ◽

Prunus Persica ◽

Control Agent ◽

Prunus Armeniaca ◽

Plant Diseases ◽

Rrna Gene ◽

Stone Fruits ◽

Initial Manifestation

The plant diseases caused by the Pseudomonas syringae сomplex bacteria are economically important and occur worldwide on various plants, and it is as a pathogen that has not been the object of studies and little is known about its epidemiology in Kyrgyzstan. The conventional phenotypic (LOPAT, API tests) and PCR-assisted isolation were used for the identificationof Pseudomonas syringae pv. syringaе isolates from the affected organs of local stone fruits, such as peach (Prunus persica), cherry (Prunus subgen), apricot (Prunus armeniaca), and plum (Prunus salicina) samples taken from the Chy, Issuk-Kul, and Batken regions of the country. 16S rRNA gene amplification was performed with primers 27F (5'-AGA GTT TGA TCC TGG CTC AG -3') and 907R (5 '–CCG TCA ATT CCT TTG AGT TT-3') for the identification of obtained P.syringae pv. syringaе isolates. From 40 primary isolates of Gram-negative rod-shaped bacteria, 12 were identified as Pseudomonas syringae pv. syringae, while the remaining isolates were identified as bacteria from Stenotrophomonas, Xanthomonas, Erwinia genera. The antagonist bio control agent—Streptomyces bacteria strains were screened and selected against the bacterial canker pathogen in in vitro experiments and on apricot seedlings in vivo conditions. Obtained results could encourage to develop a local bio-product based on this bioagent for spraying stone fruits with the initial manifestation of disease symptoms and to conduct preventive treatments in the fall and spring to increase the plant's resistance to pathogens.

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Endophytic Bacteria Bacillus subtilis, Isolated from Zea mays, as Potential Biocontrol Agent against Botrytis cinerea

Biology ◽

10.3390/biology10060492 ◽

2021 ◽

Vol 10 (6) ◽

pp. 492

Author(s):

Hernando José Bolivar-Anillo ◽

Victoria E. González-Rodríguez ◽

Jesús M. Cantoral ◽

Darío García-Sánchez ◽

Isidro G. Collado ◽

...

Keyword(s):

Zea Mays ◽

Bacillus Subtilis ◽

Botrytis Cinerea ◽

Endophytic Bacteria ◽

Biochemical Properties ◽

Plant Diseases ◽

Phytopathogenic Fungus ◽

Economic Losses

Plant diseases are one of the main factors responsible for food loss in the world, and 20–40% of such loss is caused by pathogenic infections. Botrytis cinerea is the most widely studied necrotrophic phytopathogenic fungus. It is responsible for incalculable economic losses due to the large number of host plants affected. Today, B. cinerea is controlled mainly by synthetic fungicides whose frequent application increases risk of resistance, thus making them unsustainable in terms of the environment and human health. In the search for new alternatives for the biocontrol of this pathogen, the use of endophytic microorganisms and their metabolites has gained momentum in recent years. In this work, we isolated endophytic bacteria from Zea mays cultivated in Colombia. Several strains of Bacillus subtilis, isolated and characterized in this work, exhibited growth inhibition against B. cinerea of more than 40% in in vitro cultures. These strains were characterized by studying several of their biochemical properties, such as production of lipopeptides, potassium solubilization, proteolytic and amylolytic capacity, production of siderophores, biofilm assays, and so on. We also analyzed: (i) its capacity to promote maize growth (Zea mays) in vivo, and (ii) its capacity to biocontrol B. cinerea during in vivo infection in plants (Phaseolus vulgaris).

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Vibrio harveyi virulence gene expression in vitro and in vivo during infection in black tiger shrimp Penaeus monodon

Diseases of Aquatic Organisms ◽

10.3354/dao03475 ◽

2020 ◽

Vol 139 ◽

pp. 153-160

Author(s):

S Peeralil ◽

TC Joseph ◽

V Murugadas ◽

PG Akhilnath ◽

VN Sreejith ◽

...

Keyword(s):

Gene Expression ◽

Virulence Genes ◽

Vibrio Harveyi ◽

Penaeus Monodon ◽

Challenge Test ◽

Virulence Gene ◽

Economic Losses ◽

Virulence Gene Expression

Luminescent Vibrio harveyi is common in sea and estuarine waters. It produces several virulence factors and negatively affects larval penaeid shrimp in hatcheries, resulting in severe economic losses to shrimp aquaculture. Although V. harveyi is an important pathogen of shrimp, its pathogenicity mechanisms have yet to be completely elucidated. In the present study, isolates of V. harveyi were isolated and characterized from diseased Penaeus monodon postlarvae from hatcheries in Kerala, India, from September to December 2016. All 23 tested isolates were positive for lipase, phospholipase, caseinase, gelatinase and chitinase activity, and 3 of the isolates (MFB32, MFB71 and MFB68) showed potential for significant biofilm formation. Based on the presence of virulence genes, the isolates of V. harveyi were grouped into 6 genotypes, predominated by vhpA+ flaB+ ser+ vhh1- luxR+ vopD- vcrD+ vscN-. One isolate from each genotype was randomly selected for in vivo virulence experiments, and the LD50 ranged from 1.7 ± 0.5 × 103 to 4.1 ± 0.1 × 105 CFU ml-1. The expression of genes during the infection in postlarvae was high in 2 of the isolates (MFB12 and MFB32), consistent with the result of the challenge test. However, in MFB19, even though all genes tested were present, their expression level was very low and likely contributed to its lack of virulence. Because of the significant variation in gene expression, the presence of virulence genes alone cannot be used as a marker for pathogenicity of V. harveyi.

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