<i>Bacillus subtilis Strains</i>with Antifungal Activity against the Phytopathogenic Fungi

Bacillus strains isolated from the rhizosphere soil of potato roots were evaluated for the potential antagonistic activity against fungal pathogens in vitro and in vivo. Two bacterial isolates were identified as new Bacillus subtilis strains by 16S rRNA and GyrB gene sequencing and were designated GM2 and GM5, respectively. Strains were characterized by their ability to inhibit growth of a number of phytopathogenic fungi. It was shown that GM5 strain inhibited growth of phytopathogenic fungi more effectively than GM2 strain. Both strains were capable of producing a number of hydrolytic enzymes as well as antimicrobial metabolites (ammonia and HCN). In addition, GM2 strain also produced siderophores. Four genes encoding antimicrobial peptides were identified in the genome of GM2 strain: ituC, bmyB, bacA and srfA. Genome of GM5 contained two genes encoding for antimicrobial peptides, srfA and fenD. Purified lipopeptide fraction from GM5 but not from GM2 strain was able to control Fusarium solani spread in the plate assay. Furthermore, Bacillus subtilis strain GM2 promoted growth of wheat but only GM5 strain was able to protect wheat seedlings from Fusarium oxysporum infection.

PCR-Mediated Detection of Endophytic and Phytopathogenic Fungi from Needles of the Japanese Black Pine, <i>Pinus thunbergii</i>

A specific and sensitive polymerase chain reaction (PCR) assay based on the internal transcribed spacer (ITS) region of rDNA sequences was developed to detect endophytic and phytopathogenic fungi from needles of the Japanese black pine, Pinus thunbergii. Sequences of the ITS regions of Lophodermium conigenum, Lecanosticta acicola, Pestalotiopsis neglecta, Rhizosphaera kalkhoffii, and Septorioides pini-thunbergii were compared, and each specific primer pair for these species was designed. First, the designed primer pairs were tested for their specificity to detect each species. A PCR product was amplified only each combination of species and its specific primer pair, confirming the specificity of the designed primer pairs. These primer pairs were also tested on DNA extracted from the needles of P. thunbergii. The PCR products were amplified not only in needles with lesions but also in healthy needles without symptoms. Furthermore, several endophytic and phytopathogenic fungi could be simultaneously detected from the same region in a needle. The PCR-mediated detection method developed in this study will be a valuable tool for the detection of the endophytic and phytopathogenic fungi, not only as a rapid diagnostic tool for early detection but also for monitoring variations in both the quality and quantity of the endophytic and phytopathogenic fungi in needles in Japanese black pines.

Isolation and Screening of Silicate Bacteria from Various Habitats for Biological Control of Phytopathogenic Fungi

Silicate solubilizing bacteria (SSB) can play an efficient role in soil by solubilizing insoluble forms of silicates. In addition to this some SSB can also solubilize potassium and phosphates, hence increasing soil fertility and enhancing plant defense mechanisms. A total of 111 bacterial strains were isolated from various habitats of Pakistan and screened for solubilization of silicate, phosphate and potassium on respective media. Out of these, 35 bacterial isolates were capable of solubilizing either silicate, phosphate or potassium. Amongst these 7 bacterial isolates were capable of solubilizing all three minerals tested. The highest silicate (zone diameter 54 mm) and phosphate solubilization (zone diameter 55 mm) was observed for bacterial isolate NR-2 while the highest potassium solubilization was observed for NE-4b (zone diameter 11 mm). Dual culture antagonistic assays were carried out by using these bacterial isolates against four plant pathogenic fungi Magnaporthae grisae, Rhizoctonia solani, Altarnaria alternata and Macrophomina pheasolina. Mean zone of inhibition of these bacterial isolates against the four pathogenic fungi ranged between 4 mm to 39 mm. The largest zone of inhibition against all four bacterial strains was recorded for bacterial isolate NR-2 followed by NE-4b. These strains will be further investigated for their plant growth promoting activities in the future.

Antiviral Effect of Ribonuclease from <i>Bacillus pumilus</i>against Phytopathogenic Rna-Viruses

Background: Viruses can cause different diseases in plants. To prevent viral infections, plants are treated with chemical compounds and antiviral agents. Chemical antiviral agents usually have narrow specificity, which limits their wide application. Alternative antiviral strategy is associated with the use of microbial enzymes, which are less toxic and are readily decomposed without accumulation of harmful substances. The aim of this work is to study the effect of Bacillus pumilus ribonuclease on various phytopathogenic viruses with specific focus on the ability of enzyme to eliminate them from plant explants in vitro. Materials and methods: Extracellular ribonuclease of B. pumilus is tested as an antiviral agent. To study the antiviral effect of RNase, depending on concentration and the time of application several plant-virus model systems are used. Virus detection is conducted by serological testing and RT-PCR. Results: Bacillus pumilus ribonuclease possesses antiviral activity against plant Rna-viruses RCMV (red clover mottle virus), PVX (Potato Virus X) and AMV (Alfalfa Mosaic Virus). The maximum inhibitory effect against actively replicating viruses is observed when plants are treated with the enzyme in the concentration of 100 ug/ml prior to infection. In case of local necrosis ribonuclease in the concentration of 1 ug/ml completely inhibits the development of RCMV virus on bean plants. The enzyme is able to penetrate plants and inhibit the development of viral infection, inhibiting effect for untreated surfaces decreased on average for 20%. It is also found that B. pumilus ribonuclease protects apical explants of sprouts of potato tubers from PVM and PVS viruses. Conclusion: B. pumilus ribonuclease possesses antiviral activity against plant Rna-viruses and produces viruses-free plants in the apical meristem culture.

Discovery of cryptolepine derivatives as novel promising agents against phytopathogenic bacteria

To ensure the production of food crops,a series of cryptolepine derivatives were synthesised,after which their antibacterial activities and mechanism of action against three plant pathogens were investigated.Our bioassay results indicated that most of the target compounds displayed potent inhibitory effects against Xanthomonas oryzae(X.oryzae)and Xanthomonas axonopodis pv.citri(X.axonopodis pv.c.).Remarkably,compound 9 exhibited the best in vitro antibacterial activity against X.oryzae,with a minimum inhibitory concentration(MIC)value of 0.78μg·mL^(-1).Compound 2 exhibited the best in vitro antibacterial activity against X.axonopodis pv.c.,with an MIC value of 0.39μg·mL^(-1).These activities were superior to those of copper quinolate(MIC=6.25,25μg·mL^(-1))and thiodiazole copper(MIC=100,200μg·mL^(-1))against X.oryzae and X.axonopodis pv.c.In vivo experiments demonstrated the promising applicability of compound 9 for the control of rice bacterial infections.Furthermore,compound 9 was selected as a candidate to conduct preliminary analyses of the antibacterial mechanisms of cryptolepine derivatives.Scanning electron microscopy and transmission electron microscopy observations,extracellular polysaccharide production,biofilm formation,transcriptomic,quantitative reverse transcription-polymerase chain reaction analyses,and molecular docking assays were performed.Collectively,our findings demonstrated that compound 9 might act via multifarious mechanisms to down-regulate virulence factors and cause cell death.

Release of active oxygen from phytopathogenic bacteria and their regulation

Some phytopathogenic bacteria including Xanthomonas oryzae pv. oryzae （a rice leaf bacterial blight pathogen） and its virulent gene mutant XooM3105,Xanthomonas campestris pv. campestris, Erwinia carotovora subsp, carotovora and so on, could release active oxygen such as O2 and H2O2 by themselves.Ca2+, NADPH and O2 concentration regulated the response. The response is sensitive to heat and proteinase. These results show that the component releasing active oxygen in the bacterial plant pathogen may involve special protein and enzyme and be secreted to culture liquid. Various components of rice tissue can significantly induce the release of active oxygen in Xanthomonas oryzae pv. oryzae.

Design, synthesis and SAR study of novel sulfonylurea derivatives containing arylpyrimidine moieties as potential anti-phytopathogenic fungal agents

Acetohydroxyacid synthase(AHAS) was considered as a promising target for antifungal agents.Herein,three series of novel sulfonylureas(SUs) 9-11 containing aromatic-substituted pyrimidines were designed and synthesized according to pharmacophore-combination and bioisosterism strategy.The in vitro fungicidal activities against ten phytopathogenic fungi indicated that most of the title compounds exhibited broad-spectrum and excellent fungicidal activities.Based on the preliminary fungicidal activities,a CoMFA model was constructed and the 3 D-QSAR analysis indicated that either a bulky group around the 5-position of the pyrimidine ring or electropositive group around the 2-position of the benzene ring would be favour to fungicidal activities.In order to study interaction mechanism,10 k was automatically docked into yeast AHAS and it further indicated that bearing bulky groups-aryl at the pyrimidine ring was critical to enhance antifungal activities.It revealed that the antifungal activity of derivatives 9-11 probably results from the inhibition of fungal AHAS.Thus,the present results strongly showed that SUs should be considered as lead compounds or model molecules to develop novel antiphyt o pathogenic fungal agents.

Effect of 4% glycerol and low aeration on result of expression in <i>Escherichia coli</i>of Cin3 and three <i>Venturia inaequalis</i>EST’s recombinant proteins

The phytopathogenic fungus Venturia inaequalis causes scab of apple. Once this fungus penetrates the plant surface, it forms a specialized body called a stroma between the inner cuticle surface and the epidermal cell wall. A novel Venturia inaequalis 5704 (Cin3) and three expressed sequence tags (ESTs);38, 6987, and 4010 are strongly up-regulated in the early stages of infection. The CIN3 and three ESTs using two vectors pMAL-c2 and pET 21 were expressed in Escherichia coli. Recombinant proteins expression, solubility and yields were analyzed. 38, 5704 (Cin3) and 6987 re- combinant proteins were expressed in soluble form and while 4010 was expressed in inclusion bodies. Re- solution on native-PAGE, the recombinant proteins;38, 5704 (Cin3), 6987 were shown to be present in dimmer, tetramer and polymer. A method was de- veloped, consisting of induction of expression at va- rious temperatures, and using enriched broth with 4% glycerol together with slow shaking, led to a decrease in concentration of nascent polypeptide and production of soluble recombinant proteins of;38, 5704 (Cin3), 6987 and 4010. Resolution on native- PAGE, the recombinant proteins were shown to be present as monomer.

Identification and Expression of Some Plant Cell Wall-Degrading Enzymes Present in Three Ontogenetics Stages of Thecaphora frezii, a Peanut (<i>Arachis hypogaea</i>L.) Pathogenic Fungus

Peanuts can be affected by the presence of pathogenic microorganisms. The fungus Thecaphora frezii (T. frezii), which belongs to the taxonomic class Ustilaginomycetes, is the causal agent of the disease known as “peanut smut”. The life cycle of this fungus includes three stages, namely teliospores, basidiospores and hyphae. In the hyphae stage, infection occurs in the peanut plant, which requires the involvement of some enzymes secreted by the fungus. These include the Plant Cell Wall-Degrading Enzymes (PCWDEs), which degrade various polysaccharides. This study aimed to identify the presence of transcript for enzymes belonging to the PCWDEs from three stages of T. frezii. For this, total RNA was extracted from the three ontogenetic stages of T. frezii. These samples were analyzed using an RNA-Seq approach and some transcripts were quantified using Real Time PCR. The analysis of the data provided by the RNA-Seq of the three T. frezii stages, it was possible to identify some transcripts that could encode enzymes compatible with polysaccharides degradation that are part of the plant cell wall. In T. frezii transcriptome, 40 deduced proteins would be enzymes with functions of PCWDEs were identified. They were divided into 27 glycoside hydrolases;two polysaccharide lyases;three carbohydrate esterases and eight enzymes with auxiliary activities. In addition, the fungal SNF1 gene was identified whose activity could be affected by high glucose level, and indirectly influence the levels of some PCWDEs. The analysis of the PCWDEs could help to understand part of the fungal infection process and possibly find substances that can control its development.

Essential Oils from the Leaves and Flowers of Callistemon viminalis:Chemical Characterization and Evaluation of the Insecticide and Antifungal Activities

The chemical compositions of the essential oils from the leaves and flowers of Callistemon viminalis and their insecticide and fungitoxic activities were determined. The essential oil was extracted by the hydrodistillation method using a modified Clevenger apparatus. The chemical characterization was performed by GC-MS and GC-FID. The evaluation of the insecticidal activity was performed with the Myzus persicae aphid, and the antifungal potential was determined via the inhibition of the mycelial growth of Alternaria alternata, Fusarium oxysorum and Botrytis cinérea phytopathogenic fungi. The principal components of the essential oils from the leaves and flowers were eucalyptol (84.60% and 61.47%), α-pinene (10.28% and 21.48%) and α-terpineol (2.59% and 2.79%), respectively. The use of a 0.5% concentration of the essential oil from the flowers influenced the preference of aphids and their reproduction. The number of adult aphids decreased within a period of 48 hours in the presence of the essential oil from the leaves. In the test with no chance of choice, the mean number of adults decreased with both oils within 48 hours. No inhibition of the mycelial growth of the A. alternate microorganism was observed in any of the treatments with the two essential oils. However, the growth of F. oxysporum and B. cinerea fungi was inhibited. The mycelial growth of F. oxysporum was inhibited with the concentration of 100 μL&#183;Lˉ1 of the oil from the flowers and 250 μL&#183;Lˉ1 of the oil from the leaves. The inhibition of the growth of B. cinerea was observed at concentrations of 500 and 100 μL&#183;Lˉ1 for the oils from the flowers and leaves, respectively. The essential oils presented insecticidal and antifungal potentials. However, further studies are needed for these oils to be used in integrated pest management.

Antifungalmycin,an antifungal macrolide from Streptomyces padanus 702

Two polyene macrolide antibiotics:antifungalmycin(1)and fungichromin(2)were isolated from the culture mycelia of Streptomyces padanus 702 via bioactivity-guided fractionation using various chromatographic procedures.Their structures were elucidated on the basis of spectral analysis,and 1 is a new polyene macrolide.Compounds 1 and 2 showed significant inhibition against Gibberella zeae with EC_(50)values of 26.71 and 2.21μg/mL,Fusicoccum sp.(plantain head blight)with EC_(50)values of 23.4 and 3.17μg/mL,Mucor ssp.8894 with EC_(50)values of 28.80 and 2.11μg/mL,Ustilaginoidea virens with EC_(50)values of 26.72 and 0.21μg/mL,respectively.This shows that the microbial secondary metabolites 1 and 2 have the potential to be developed as agricultural fungicides for use against G.zeae,Fusicoccum sp.,Mucor ssp.8894,and U.virens.

Phytochemical Analysis and Antifungal Activity of Extracts from Leaves and Fruit Residues of Brazilian Savanna Plants Aiming Its Use as Safe Fungicides

The increasing demand for safe food without preservatives or pesticides residues has encouraged several studies on natural products with antifungal activity and low toxicity.In this study,ethanolic extracts from leaves and fruit residues(peel and seeds)of three Brazilian savanna species(Acrocomia aculeata,Campomanesia adamantium and Caryocar brasiliense)were evaluated against phytopathogenic fungi.Additionally,the most active extract was chemically characterized by ESI-MS and its oral acute toxicity was evaluated.Extracts from C.brasiliense(pequi)peel and leaves were active against Alternaria alternata,Alternaria solani and Venturia pirina with minimal inhibitory concentrations between 350 and 1000 lg/mL.When incorporated in solid media,these extracts extended the lag phase of A.alternata and A.solani and reduced the growth rate of A.solani.Pequi peel extract showed better antifungal activity and their ESI-MS analysis revealed the presence of substances widely reported as antifungal such as gallic acid,quinic acid,ellagic acid,glucogalin and corilagin.The oral acute toxicity was relatively low,being considered safe for use as a potential natural fungicide.

Analogs of Antifungal Indoles Isolated from Aporpium Caryae with Activity Against Sudden-Death Syndrome of Soybean

Based on the precedent discovery of a weak antifungal indole isolated from Aporpium caryae, which increased its activity when changing the N-alkyl chain, nineteen N-alkyl indoles, with alkyl chains from one to ten carbons and one or two hydroxyls, one amine or bromine functional groups, were prepared and fully characterized by spectroscopic methods. The aim of this study is the search for new synthetic agrochemical leads derived from natural products. The antifungal activity of the synthesized compounds against three fungal strains was measured in vitro. Six compounds presented good activity against Fusarium virguliforme, the causal agent of sudden-death syndrome (SDS) in soybean, in a bioautography assay. Four of them were tested in a germination test and in a greenhouse experiment. All tested compounds, applied as seed treatment, showed antifungal properties being effective to control SDS when there was low level of fungal contamination. Results indicate that some of the tested compounds are acting as growth inhibitors and represent new leads for the treatment of SDS for which no specific treatment has been previously reported.

Dispersion of the Bacterium Xylella fastidiosa in Portugal

After the first detection of the gram-negative bacterium,Xylella fastidiosa multiplex in Portugal,in January 2019,a“Demarcated Area”was delimited and an“Action Plan”to control the pathogen has been developed.It is considered one of the greatest threats to plant health worldwide and leads to loss of forests vitality and productivity.The current study was developed till June 2020,with the objective to understand the dimension of the issue worldwide and in Portugal,analyzing the state-of-the-art on the biology,dispersion,symptoms,control and risks associated with this bacterium(Research Phase).In the Prospecting Phase,we collected 5 branches with 5-8 leaves,from the four quadrants of the tree,wrapping and labeling them-so 2,261 samples were collected and sent to the laboratory for analysis.It was possible to determine that the two initial outbreaks were not an isolated case,as 107 additional outbreaks were detected in other places,revealing a much more worrying panorama,requiring further analysis on the real impact of this bacterial strain on the natural environment.By the end of this study the demarcated area covered about 62,000 ha.The most affected species was lavender with 30%of positive outbreaks,followed by gorse with 22%,and rosemary with 11%.Spread of Phillaenus spumarius and X.fastidiosa indicates that insect vector and transport links appear to be dispersal facilitators together with Douro River.As eradication is unfeasible to achieve in the coming years,containment will be the most appropriate strategy.

Behavior of the Fungus <i>Colletotrichum gloeosporioides</i>(Penz &Sacc.), Which Causes Bitter Rot in Apples after Harvesting

The apple is the second most important fruit in Brazil. However, apple cultivars are susceptible to several diseases that can cause losses after harvesting. Bitter rot is caused by the fungus Colletotrichum gloeosporioides and is one of the most damaging summer diseases. The goal of this work was to evaluate the behavior of this fungus in four apple cultivars grown in Brazil (Fuji, Gala, Golden and Green) under two treatments: direct inoculation and isolated fungus. The fungus was isolated by taking fragments from infected fruits, which were stored on Potato Dextrose Agar (PDA) in a laboratory. For the direct treatment, the fungus was removed from infected fruits and directly inoculated into healthy fruits. After inoculation, the fruits were kept at room temperature and the halos of degradation were evaluated every 48 hours. The results demonstrated that direct inoculation was more pathogenic, that the Gala cultivar was the most resistant to the pathogen, and that the Golden cultivar was the most susceptible.

Host Range and Virulence of a Fungal Pathogen for Control of Giant Salvinia (<i>Salvinia molesta</i>)

A teleomorph of the fungus Botryosphaeria rhodina (Berkeley et Curtis) von Arx, (Br) was evaluated as a bioherbicide for control of giant salvinia (Salvinia molesta D.S. Mitchell) under greenhouse conditions and in small-scale field trials. We found that fungal mycelium was highly infective and could be rapidly produced (48+ h) in soy flour-cornmeal liquid media contained in shake flasks or fermenters. A dew period was not required to achieve infection and mortality of inoculated plants. A surfactant (Silwet L-77, a polyalkyleneoxide modified heptamethyl-trisiloxane) incorporated in the fungal formulation was required for Br to infect and kill plants. Infection and mortality occurred rapidly (within 48 h after treatment), and re-growth of treated plants did not occur. In replicated field trials, Br controlled giant salvinia ~95%. Br also infected other plants, such as common salvinia (S. minima Baker), and Azolla filiculoides Lam., as determined in ongoing host range research. However, no symptomatology was observed on several economically important crop species, such as rice (Oryza sativa L.), corn (Zea mays L.), and several woody species such as bald cypress (Taxodium distichum L.) and loblolly pine (Pinus taeda L.) occurring in areas where giant salvina occurs that would be subject to contact with releases of Br. These results suggest that this teleomorph of Botryosphaeria rhodina has potential as a bioherbicide for controlling this onerous aquatic weed.

A Comparative Study of Different Strains of Trichoderma under Different Conditions of Temperature and pH for the Control of Rhizoctonia solani

Severe damage caused by R. solani in the potato crop and the current limitations for its control justify the assessment of potential biocontrol agents and their relationship with abiotic factors to be successfully included in sustainable production systems. The aim of this study was to test the effect of temperature (10&#730;C, 15&#730;C, 25&#730;C, 35&#730;C) and pH (5.5, 7, 8.5) on the growth and antagonist mechanisms of 26 native strains of 11 species of Trichoderma for the control of R. solani. The response obtained was dependent on the isolation, rather than on the Trichoderma specie that was tested. Most of them showed greater growth at 25&#730;C and pH 5.5, with overgrowth values between 75% and 100% and greater percentage of radial growth inhibition (PRGI) at 50%. A greater ability to compete for the substrate is observed, enhanced by its higher growth rate. Hyphal interaction mechanisms were varied and, at least, 92% of the isolations showed a minimum of two different types. Knowledge of the behavior of the different strains in front of varied abiotic factors will enable an understanding of the population dynamic of Trichoderma and the identification of the most efficient strains for the control of R. solani.

Antifungal Activity of Oleoresin and Fractions of Pinus elliottii Engelm and Pinus tropicalis against Phytopathogens

Microorganism resistance to the existing products is yet another difficulty that agriculturalists have to deal with. In this context, the search for new agricultural products that can fight phytopathogens has become increasingly important. Plants have played an important role in this process, because they can serve as a source of new compounds for drug discovery. Plants belonging to the genus Pinus produce an oleoresin that protects the plant against herbivores and pathogens. With a view to developing products that can combat fungal pathogens without harming the environment, this work aimed to evaluate the antifungal activity of the oleoresins and fractions of Pinus elliottii Engelm and Pinus tropicalis against phytopathogens. The methodology based on NCCLS M38-A standards aided antifungal activity assessment. The microdilution method helped to determine the Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC). The oleoresins of P. elliottii and P. tropicalis afforded the most significant results—they displayed fungicidal activity against all the tested species. MIC values were promising, especially the MIC of the oleoresin of P. elliottii against S. rolfsii (1.95 μg·mL-1). The MIC values of the oleoresins of P. elliottii and P. tropicalis ranged from 1.95 to 1000 μg·mL-1 and from 31.25 to 250 μg·mL-1, respectively. Fraction PT2 of P. tropicalis furnished the best results among all the assayed fractions: MIC values lay between 125 and 500 μg·mL-11. In conclusion, the oleoresin of P. tropicalis is a promising source of new antifungal agents for application in the treatment of phytopathogenic infections.

Improving ITS sequence data for identification of plant pathogenic fungi

Plant pathogenic fungi are a large and diverse assemblage of eukaryotes with substantial impacts on natural ecosystems and human endeavours.These taxa often have complex and poorly understood life cycles,lack observable,discriminatory morphological characters,and may not be amenable to in vitro culturing.As a result,species identification is frequently difficult.Molecular(DNA sequence)data have emerged as crucial information for the taxonomic identification of plant pathogenic fungi,with the nuclear ribosomal internal transcribed spacer(ITS)region being the most popular marker.However,international nucleotide sequence databases are accumulating numerous sequences of compromised or low-resolution taxonomic annotations and substandard technical quality,making their use in the molecular identification of plant pathogenic fungi problematic.Here we report on a concerted effort to identify high-quality reference sequences for various plant pathogenic fungi and to re-annotate incorrectly or insufficiently annotated public ITS sequences from these fungal lineages.A third objective was to enrich the sequences with geographical and ecological metadata.The results-a total of 31,954 changes-are incorporated in and made available through the UNITE database for molecular identification of fungi(http://unite.ut.ee),including standalone FASTA files of sequence data for local BLAST searches,use in the next-generation sequencing analysis platforms QIIME and mothur,and related applications.The present initiative is just a beginning to cover the wide spectrum of plant pathogenic fungi,and we invite all researchers with pertinent expertise to join the annotation effort.

New antibacterial depsidones from an ant-derived fungus Spiromastix sp.MY-1

Six new(1–6)and seven known depsidones(7–13)were isolated from the culture of an ant(Monomorium chinensis)-derived fungus Spiromastix sp.MY-1.Their structures were elucidated by extensive spectroscopic analysis including high resolution MS,1D and 2D NMR data.The new bromide depsidones were obtained through supplementing potassium bromide in the fermentation medium of Spiromastix sp.MY-1.All isolated compounds showed various bioactivities against the tested phytopathogenic bacteria.Particularly,new bromide compound 4,named spiromastixone S,exhibited the strongest activity against Xanthomonas oryzae pv.oryzae with a MIC value of 5.2μmol·^L(−1).