Isolation of Endophyte and Screening for Antagonistic Bacteria in Solanaceae

[ Objective] The aim of this study was to isolate the endophyte of three solanaceae fruits and vegetables such as tomato, pepper and eggplant, to screen and identify the bacterial wilt antagonistic bacteria. [ Methodl According to the lapping liquid culture method, the endophyte of three plants was isolated by the selective medium and purified by the plate streaking method, so the purified enclophyte was screened by the hyphal pieces confront culture method. Furthermore, the screened antagonistic and endophyteic bacteria was identified and classified through culture characteristics of isolates and morphological features of thallus, Gram stain as well as physiological and biochemical reactions. [ Result] Fifty-three endophytic bacteria, fifty-three endophytic fungi and forty-four endophytic actinomycetes were separated from the endophyte of three plants. The screened fourteen endophytic bacteria with strong antagonistic effect on the bacterial wilt were classified to Bacillus, Escherichia, Klebsiella, Agromonas, Erwinia and Curto Bacterium respectively. Especially, Bacillus was the dominant species, which had the strongest antagonistic effect on the bacterial wilt. [ Conclusion] This study provides an effective way for biological control of the bacterial wilt in solanaceae.

Inhibition Effect of Antagonistic Fungal Strain BOS-013 against the Pathogen of Rice Blast (Pyricularia oryzae)

[ ObjeeUve ] To search for the beneficial microorganisms and their metabolic products with control effect against rice Mast, the paper studied the inhibi- tion effect of the fermentation broth of actinomycetes BOS-013 strain against the pathogen of rice blast （Pyricularia oryzae）. [ Method ] With P. oryzae as the target indicator fungus, the inhibition effect of the fermentation broth of BOS-013 strain and its extracts from different solvents against the pathogen were determined using cylinder plate method and filter paper method. [ Result] The results showed that the inhibition rate of the fermentation broth of BOS-013 strain with fungus amount of 4×10^8 cfu/ml against P. oryzae was 92.0% ±0.5% ; the fermentation broth still had inhibition effect against P. oryaae after inactivation under high temperature and high pressure, and the inhibition rate was 60.0%±0.5%. After absorbed by non-polar CAD-45 type macroperous adsorption resin and eluted by 60% etha- nol, the antifungal activity of the fermentation broth was still high, and the diameter of inhibition zone reached 33.0 mm. [ Conclusion] The fermentation broth of BOS-O13 strain had significant inhibition effect against P. oryzae. The results would provide foundation for further clarification of inhibition mechanism of BOS-013 strain fermentation broth against P. oryzae and its practical application.

Isolation of High-virulence Strains and Antagonistic Bacteria of the Pathogen of Ginger Blast (Ralstonia solanacearum)

[ Objective] The paper was to screen Bacillus with strong antagonistic effect. [ Method] The diseased ginger and the surrounding soils were collected from Laiwu of Shandong Province, and the high-virulence strains of the pathogen of ginger blast （Ralstonia solanacearum） were isolated, Bacillus was used to carry out antagonistic test. [Result] Three strains LW-4, LW-7 and LW-32 had strong antagonistic effect against R. solanacearum, the area of their inhibition zone was larger than other strains. [ Conclusion] The study provided theoretical basis for the control of ginger blast.

Synergistic and antagonistic interactions between potassium and magnesium in higher plants

Magnesium(Mg)affects various critical physiological and biochemical processes in higher plants,and its deficiency impedes plant growth and development.Although potassium(K)-induced Mg deficiency in agricultural production is widespread,the specific relationship of K with Mg and especially its competitive nature is poorly understood.This review summarizes current knowledge on the interactions between K and Mg with respect to their root uptake,root-to-shoot translocation and distribution in plants.Their synergistic effects on certain physiological functions are also described.The antagonistic effect of K on Mg is stronger than that of Mg on K in root absorption and transport within plants,indicating that the balanced use of K and Mg fertilizers is necessary for sustaining high plant-available Mg and alleviating K-induced Mg deficiency,especially in plant species with high K demand or in highavailable-K soil.The relationship between Mg and K in plant tissues may be antagonistic or synergistic depending on plant species,cell type,leaf age,source-and sink organs.There are synergistic effects of K and Mg on photosynthesis,carbohydrate transport and allocation,nitrogen metabolism,and turgor regulation.Definition of optimal K/Mg ratios for soils and plant tissues is desirable for maintaining proper nutritional status in plants,leading to a physiological state supporting crop production.Future research should concentrate on identifying the physiological and molecular mechanisms underlying the interactions between K and Mg in a given physiological function.

Poly(ADP-ribosyl)ation of Apoptosis Antagonizing Transcription Factor Involved in Hydroquinone-Induced DNA Damage Response

The molecular mechanism of DNA damage induced by hydroquinone （HQ） remains unclear. Poly（ADP-ribose） polymerase-1 （PARP-1） usually works as a DNA damage sensor, and hence, it is possible that PARP-1 is involved in the DNA damage response induced by HQ. In TK6 cells treated with HQ, PARP activity as well as the expression of apoptosis antagonizing transcription factor （AATF）, PARP-1, and phosphorylated H2AX （v-H2AX） were maximum at 0.5 h, 6 h, 3 h, and 3 h, respectively. To explore the detailed mechanisms underlying the prompt DNA repair reaction, the above indicators were investigated in PARP-l-silenced cells. PARP activity and expression of AATF and PARP-1 decreased to 36%, 32%, and 33%, respectively, in the cells; however, y-H2AX expression increased to 265%. Co-immunoprecipitation （co-IP） assays were employed to determine whether PARP-1 and AATF formed protein complexes. The interaction between these proteins together with the results from IP assays and confocal microscopy indicated that poly（ADP-ribosyl）ation {PARylation） regulated AATF expression, in conclusion, PARP-1 was involved in the DNA damage repair induced by HQ via increasing the accumulation of AATF through PARylation.

Isolation and Identification of Shoot-Tip Associated Endophytic Bacteria from Banana cv. Grand Naine and Testing for Antagonistic Activity against <i>Fusarium oxysporum</i>f. sp. <i>cubense</i>

Endophytic bacteria colonizing the shoot-tips of banana cv. Grand Naine were isolated and tested for the antagonistic activity against the Panama wilt pathogen Fusarium oxysporum f. sp. cubense (Foc). Pre-isolation, the suckers were given extensive disinfection treatments and the homogenate from the excised shoot-tip portion was plated on nutrient agar (NA) and trypticase soy agar (TSA). This yielded altogether 47 isolates: 26 on NA and 21 on TSA, respectively, from the 10 suckers collected during August to February. The number of bacterial isolates obtained per sucker varied from one to 15 based on colony characteristics registering up to 10 distinct species per shoot-tip based on 16S rRNA sequence analysis. The 47 isolates belonged to 19 genera and 25 species under the phylogenetic classes of Actinobacteria, α- and γ-Proteobacteria and Firmicutes. Actinobacteria constituted the predominant phylum (55% isolates) with the constituent genera of Arthrobacter, Brevibacterium, Corynebacterium, Curtobacterium, Kocuria, Kytococcus, Micrococcus, Naumanella, Rothia and Tessaracoccus spp. and an unidentified isolate belonging to the family Frankiaceae. Proteobacteria constituted the second major phylum (Brevundimonas, Enterobacter, Klebsiella, Pseudomonas, Serratia and Sphingomonas spp.) followed by Firmicutes (Bacillus and Staphylococcus spp.). Antagonistic activity of the endophytes against Foc was tested through agar plate assays (pit and spot applications on fungal lawn) employing potato dextrose agar and NA. Endophytic Pseudomonas aeruginosa (isolate GNS.13.2a) which was associated with a single sucker showed significant growth inhibition effect on Foc while Klebsiella variicola (GNS.13.3a) and Enterobacter cloacae (GNS13.4a) exhibited moderate inhibition. The study brings out considerable sucker to sucker variation in the associated cultivable endophytic bacteria in “Grand Naine” banana and identifies a few bacterial endophytes with biocontrol potential against the devastating Foc pathogen.

Mathematical rules for synergistic,additive,and antagonistic effects of multi-drug combinations and their application in research and development of combinatorial drugs and special medical food combinations

Multi-drug(or multi-element)combinations are often prescribed in the practice of clinical medicine and as foods for special medical purposes.The main motivations for these combinations are that most diseases contain multiple related targets and an appropriate combination can maximize benefits while minimizing adverse reactions.As such,it is especially important to derive mathematical models for their quantitative calculation.In this paper,we introduce mathematical rules for the synergistic,additive,and antagonistic effects of multi-drug combinations developed in our laboratory.We have established a“onebelt,one-line”model and provide examples of the quantitative calculation of the synergistic,additive,and antagonistic effects of a combination of multiple components.We also explain how to scientifically and precisely determine the intensity of these synergies,additions and antagonisms,as well as their corresponding dose ranges,thereby laying a solid theoretical foundation for market listing combinatorial drugs and foods for special medical purposes.

Assessment of the Effect of Environmental Factors on the Antagonism of <i>Bacillus amyloliquefaciens</i>and <i>Trichoderma harzianum</i>to <i>Colletotrichum acutatum</i>

The effect of temperature (18°C - 30°C), water activity (0.85 - 1) and pH (4 - 9) was studied by dual culture technique on the antagonism of Bacillus amyloliquefaciens and Trichoderma harzianum to Colletotrichum acutatum, responsible of strawberry (Fragaria x ananassa (Weston) Duchesne ex Rozier) anthracnose. The antagonistic bacteria’s strains behave significantly and differently according to the parameters studied. These results reveal useful information about the applicability of their biocontrol in agricultural culture with the change of environmental factors.

Effects of Ca￣（2＋）ions antagonistic to Al￣（3＋）ions poisoning in root growth，cell division and nucleolus in root tip cells of Allium cepa

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In Vitro Antagonistic Activity of Trichoderma harzianum and Bacillus amyloliquefaciens against Colletotrichum acutatum

Biological control of plant diseases makes extensive use of the antagonists. The effectiveness of the control depends on the choice of an effective antagonist strains from criteria of implying a good knowledge of biological peculiarities of the material used. In this study, the antagonistic activities of nine isolates of Bacillus amyloliquefaciens and one isolate of Trichoderma harzianum were tested in vitro against seven strains of Colletotrichum acutatum, the causal agent of strawberry anthracnose. It was found that T. harzianum and B. amyloliquefaciens strains showed the ability to inhibit the mycelial growth of the pathogen by dual culture technique by more than 50 percent. The nonvolatile substances produced by the antagonists showed high inhibition percentages that are more than 99 percent, meanwhile their volatile compounds inhibited the mycelial growth of C. acutatum strains with low inhibition percentages starting from 30 percent except the substances produced by B. amyloliquefaciens Bc2 that showed a high inhibition percentage of more than 70 percent.

Effect of Synergism and Antagonism between Metals on Toxicity in Soils

Synergism and antagonism of cadmium (Cd), copper (Cu) and selenium (Se) to biological toxicities in red soil, yellow brown soil and black soil were evaluated by MICROTOX method. The relation between forms of the tested metals in soil and the synergism or antagonism between them was also studied.Results showed that owing to the difference of soil chemical properties, toxicity of these metals in soils was different. In red soil with acid reaction and low in cation exchange capacity, antagonism occurred significantly between metals when they coexisted at high concentrations, while synergism occurred only under low concentrations. It is indicated that in red soil, toxicity of metals affected by synergism or antagonism depends on concentration of the metals present. For yellow brown soil and black soil with larger cation exchange capacity and lower exchangeable aluminium (A1), no toxicity of metals was observed even if metals were added to soil in high concentrations. Synergism and antagonism between Cd, Cu and Se were controlled by the forms of metals present. The amount of water-soluble metals was the most important factor in determining synergism and antagonism.In this paper, comparisons of synergism and antagonism between metals in soils and in water solutions were made. There occurred the synergism of metal toxicity in water solutions when the concentration of coexisting metals was high. This is just opposite to the case in soils.

Antagonistic Potential of Bacterial Species against Fungal Plant Pathogens(FPP)and Their Role in Plant Growth Promotion(PGP):A Review

Since the 19th century to date,the fungal pathogens have been involved in causing devastating diseases in plants.All types of fungal pathogens have been observed in important agricultural crops that lead to significant pre and postharvest losses.The application of synthetic fungicide against the fungal plant pathogens(FPP)is a traditional management practice but at the same time these fungicides kill other beneficial microbes,insects,animal,and humans and are harmful to environment.The antagonistic microorganism such as bacteria are being used as an alternate strategy to control the FPP.These antagonistic species are cost-effective and eco-friendly in nature.These biocontrol bacteria have a broad mechanism against fungal pathogens present in the phyllosphere and rhizosphere of the plant.The antagonistic bacteria have different strategies against the FPP,by producing siderophore,biofilm,volatile organic compounds(VOCs),through parasitism,antibiosis,competition for limited resources and induce systemic resistance(ISR)in the host plant by activating the immune systems.The commercial bio-products synthesized by the major bacterial species Pseudomonas syringae,Burkholderia cepacia,Streptomyces griseoviridis,Pseudomonas fluorescens and Bacillus subtilis are used to control Fusarium,Pythium,Rhizoctonia,Penicillium,Alternaria,and Geotrichum.The commercial bio-formulations of bacteria act as both antifungal and plant growth regulators.The Plant growth-promoting rhizobacteria(PGPR)played a significant role in improving plant health by nitrogen-fixing,phosphorus solubilization,phytohormones production,minimizing soil metal contamination,and by ACC deaminase antifungal activities.Different articles are available on the specific antifungal activity of bacteria in plant diseases.Therefore,this review article has summarized the information on biocontrol activity of bacteria against the FPP and the role of PGPR in plant growth promotion.This review also provided a complete picture of scattered information regarding antifungal activities of bacteria and the role of PGPR.

Screening and Identification of a Bacterial Strain Antagonistic to Vibrio parahaemolyticus

In the present study, bacterial strains were isolated from the shrimp （Penaeus orientalis） ponds in different regions of Hainan Province, and tested for their antagonistic activity against Vibrio species on 2216E plates, using V. parahaemolyticus, V. harveyi and V. anguillarum as the indicator bacteria. As a result, an antagonistic strain was screened out and numbered 20160522Z-10 （referred to as Z-10）. Then, the antibacterial activity and minimum inhibitory concentration （MIG） of Z-10 against the indicator bacteria, and its antibacterial effect against other six Vibrio species were determined. The results proved that Z-10 was antagonistic to all the three indicator bacteria, and its MIC against V. parahaemolyticus, V. harveyi and V. anguillarum was 2.5× 10^4, 2.5× 10^5 and 2.5× 10^5 CFU/ml. Additionally, Z-10 had a certain antibacterial effect against other Vibrio species. Finally, the strain was identified as a Pseudoalteromonas sp. by 16S rDNA sequence analysis. The bacterium as a new probiotic, is expected to be used in disease prevention and control in marine aquaculture.

Identification of A Strain HN-1 against Banana Wilt Disease and Determination of Its Antagonism

[Objective] The paper was to identify strain HN-1 against banana wilt disease and to determine its antagonism. [Method] The strain HN-1 was ob- tained from the soil in fields heavily infected by Fusarium oxysporum f. sp. cubense （FOC）. Antagonism of the strain against F. oxysporum was tested via dual-cul- ture and inhibition test on spore germination. [Result] HN-1 effectively inhibited mycelial growth and spore germination of F. oxysporum, Strain HN-1 was identi- fied as BrevibaciUus brevis according to its characteristics in morphology, physiology and biochemistry and its 16S rDNA sequence. The strain showed high inhibition effect on 15 species of fungal pathogens in the dual-culture trials with fungal pathogens. [ Conclusion] The study provides theoretical basis for application of strain HN-1 in agricultural fields.

Growth and Antagonism of <i>Trichoderma</i>spp. and Conifer Pathogen <i>Heterobasidion annosum</i>s.l. <i>in Vitro</i>at Different Temperatures

Variations in the radial growth rate of 24 isolates belonging to ten species of Trichoderma, three isolates of conifer pathogen Heterobasidion annosum s.s. and four isolates of H. parviporum were evaluated by incubation on a solid malt extract medium at a temperature of 4℃, 15℃ and 21℃. Trichoderma antagonism against Heterobasidion was investigated in dual culture in vitro. The slowest rate of growth was referable to all seven strains of Heterobasidion spp. All Heterobasidion spp. strains were overgrown by 63% of Trichoderma spp. strains after two weeks at 21℃ and by 33% of strains at 15℃. 21% of Trichoderma strains did not grow and only four strains belonging to T. koningii, T. viride and T. viridescens demonstrated the ability to completely overgrow Heterobasidion spp. after two weeks incubation at 4℃. According to the antagonistic efficiency, Trichoderma strains were divided into five groups with an Euclidean distance of 25. The groups contained isolates from different species. It was suggested that selected psychrotrophic fast growing T. viride, T. koningii and T. viridescens strains could be examined in different substrate conditions as suitable antagonist agents for the control of H. annosum and H. parviporum.

WORLD MILITARY SITUATION 2016: ANTAGONISM INTENSIFIES BUT CRISES REMAIN CONTROLLABLE

The world military situation in 2016was complex,military strategies of major countries undergoing profound readjustment,contest in emerging fields increasing and a new round of populism cropping up worldwide which resulted in'Black swan events'happening one after another,major-country contest and geopolitical conflicts piling up and local

Isolation,identification,and antagonism protein analysis of B34 against Thanatephorus cuc-umeris

A strain B34 against Thanatephorus cucumeris was screened from rice plants. Lab and field experiments showed that the control effects of this fungal strain were better than that of Jinggangmycin on PDA plate. Based on the chemical components of cell wall and physiological and biochemical characters of B34, the fungal was named as Pseudomonas aureofaciens. It was a new antagonistic strain against Thanatephorus cucumeris.

Studies on Rhizospheric Mycoflora of Tea (Camellia sinensis): In vitro Antagonism with Dominant Bacteria

Species of Trichoderma, Penicillium, Aspergillus and Mucor were found to dominate the rhizosphere of tea bushes in different regions of the Indian Himalayas. The Himachal Himalayas were dominated by Monilia humiscola (45.08%) and Mucor hiemalis (33.11%). In the Uttaranchal Himalayas, Aspergillus clavatum dominated the rhizosphere (54.01%), followed by A. flavous (20.07%). Although the fungal isolates require a mesophillic temperature (15 ℃ to 35 ℃), the tea rhizospheric isolates tolerate a wide range of temperatures (5 ℃ to 45 ℃). When tested for pH tolerance, these fungi showed a wide range (2.0 to 13.0) of pH tolerance under in vitro conditions. Seasonal variations also influenced the colony forming units (cfu) of the rhizospheric fungi, with the maximum forming in November and March, and the minimum in December^February. During this period, the populations of the fungi were found inversely proportional to the bacterial populations. In addition, the dominant bacteria in the tea rhizosphere, i.e., Bacillus subtilis and B. mycoides, showed antagonistic activity against fungal isolates by inhibiting the growth and causing structural abnormalities in mycelium. Tab 5, Ref

Identification and Antagonism Study of a Novel Chitinase-producing Bacterium Burkholderia Sp.C3 against Phytopathogenic Fungi

Through a modified agar well diffusion assay,antagonism of a novel chitinase-producing strain C3 against the phy- topathogenic fungi including Phoma wasabiae Yokogi,Cochlibolus Heterostrophus,Exserohilum Turcicum,Curuvularia Lunata (Walk)Boed,Thantephorus cucumris,Fusarium graminearum was tested.The data showed that the crude extracts of strain C3 had stable antifungal activity in the range of pH 5.0 to pH 8.0.The active components were heat labile and sensitive to proteinase K.A series of experiments supported that the compound responsible for inhibitory aetivity appeared to be chitinase.The 16s rDNA analysis indicated that C3 was subject to genus Burkholderia.Phenotypic characterization of C3 was also consisted with the result of molecular identification.

Antagonism of local isolates of Trichoderma spp. on citrus root rot disease by Fusarium solani in the mekong delta of vietnam

The local isolates of Trichoderma spp. and Fusarium solani were colected from citrus orchards in the Mekong delta of Vietnam and isolated on PDA, PDB and TSM medium for antagonism and Koch’s postulate testing. The results showed that the high chitinolytic enzymes content of Trichoderma isolates can antagonise with Fusarium solani isolates by preventing the germination of Fusarium macroconidia in in-vitro condition. There are five promising isolates of Trichoderma spp. having high antagonism with Fusarium solani. These Trichoderma isolates also grew well in rice straws, maize stems, weeds and water hyacinth biowaste materials. These results supply the promising trend for biological control of root rot disease on citrus orchards of the Mekong delta.