Effect of antimicrobial peptides and monoterpenes on control of fire blight

Aim of study: Antimicrobial peptides and monoterpenes are safe compounds that have been used for control of many plant diseases. Herein, the effects of two recombinant antibacterial peptides (AMPs) were compared with two monoterpenes for control of Erwinia amylovora directly or via induction of plant defense enzyme guaiacol peroxidase (GPOD).Area of study: The experiments were performed at the Ferdowsi University of Mashhad (Iran).Material and methods: The central composite design (CCD) method was used to study the effect of mixing the compounds and copper compound (Nordox) in controlling the pathogen. The resistance level was studied on shoots of tolerant (‘Dargazi’) and semi-susceptible (‘Spadona’) pear cultivars treated with the antibacterial compounds.Main results: Thanatin and 1,8-cineole showed the highest and lowest antibacterial effects. All treatments reduced E. amylovora pathogenicity on blossom. The CCD analysis revealed that the best reduction in colony number obtained by mixing Lfc, thanatin, thymol, 1,8-cineole and Nordox at concentrations of 32, 16, 24, 250 and 250 μg/mL. Thymol and 1,8-cineole at 500 μg/mL decreased disease severity significantly compared to that of AMPs. The level of GPOD enzyme in ‘Dargazi’ was higher than in ‘Spadona’. All treatments increased the GPOD levels in both cultivars. Furthermore, resistance level and GPOD ratio were negatively correlated.Research highlights: Antimicrobial peptides showed better effect on growth inhibition of E. amylovora than monoterpenes. Mixing of these peptides and monoterpens at special dosage enhanced their antimicrobial efficacy against E. amylovora; that could represent a new method in control of fire blight disease

Intelligent adaptive multi-parameter migration model for load balancing virtualized cluster of servers

Najvažnija korist virtualizacije je dobivanje okruženja s ujednačenim opterećenjem kroz prenošenje (migraciju) virtualnim strojem (VM). Djelovanje usluga u skupinama (klasterima), kao što je prosječno vrijeme reakcije - Average Response Time - reducirano je inteligentnom odlukom VM o prenošenju. Prenošenje ovisi o nizu kriterija poput korištenja resursa (uporaba CPU, korištenje RAMa, korištenje mreže, itd.) i potrebe za strojevima (fizičkim (PM) i virtualnim (VM)). To je više- kriterijski problem prenošenja koji procjenjuje, komparira i sortira niz fizičkih i virtualnih strojeva (PM i VM) na osnovu parametara istaknutih u procesu prenošenja. Ali, koji parametar (parametri) ima dominantnu ulogu nad djelovanjem klastera u određenom vremenskom odjeljku? Kako možemo odrediti težinu parametara u nadolazećim vremenskim razmacima? Postojeći algoritmi prenošenja (migration algorithms) ne uzimaju u obzir težine parametara koje se mijenjaju ovisno o vremenu. Te analize pretpostavljaju fiksnu težinu za svaki parametar kroz široki raspon vremenskih intervala. To dovodi do netočnog predviđanja o traženju rješenja za svaki server. U našem se radu predstavlja novi Inteligentni i Adaptivni Multi Parametarski (IAMP) upravljač resursima na bazi prenošenja (migracije) za virtualizirane centre podataka i klastere s novom na umjetnoj neuronskoj mreži (ANN) temeljenoj analizi težina nazvanoj Error Number of Parameter Omission (ENPO). U svakom se vremenskom razmaku težina parametara ponovo izračunava te će nevažni parametri biti oslabljeni u postupku rangiranja. Obilježili smo parametre koji utječu na performansu klastera i koristili hot migration s naglaskom na skupini servera u XEN platformi virtualizacije. Eksperimentalni rezultati temeljeni na radnim opterećenjima sastavljenim od stvarnih aplikacija pokazuju da je primjenom IAMP-a moguće poboljšati rad virtualnog klaster sustava do 23 % u usporedbi s postojećim algoritmima. Što više, on brže reagira i eliminira vruće točke zbog svog potpuno dinamičkog upravljačkog algoritma.The most important benefit of virtualization is to get a load balanced environment through Virtual Machine (VM) migration. Performance of clustered services such as Average Response Time is reduced through intelligent VM migration decision. Migration depends on a variety of criteria like resource usage (CPU usage, RAM usage, Network Usage, etc.) and demand of machines (Physical (PM) and Virtual (VM)). This is a multi-criteria migration problem that evaluates, compares and sorts a set of PMs and VMs on the basis of parameters affected on migration process. But, which parameter(s) has dominant role over cluster performance in each time window? How can we determine weight of parameters over oncoming time slots? Current migration algorithms do not consider time-dependent variable weights of parameters. These studies assume fixed weight for each parameter over a wide range of time intervals. This approach leads to imprecise prediction of recourse demand of each server. Our paper presents a new Intelligent and Adaptive Multi Parameter migration-based resource manager (IAMP) for virtualized data centres and clusters with a novel Artificial Neural Network (ANN)-based weighting analysis named Error Number of Parameter Omission (ENPO). In each time slot, weight of parameters is recalculated and non-important ones will be attenuated in ranking process. We characterized the parameters affecting cluster performance and used hot migration with emphasis on cluster of servers in XEN virtualization platform. The experimental results based on workloads composed of real applications, indicate that IAMP management framework is feasible to improve the performance of the virtualized cluster system up to 23 % compared to current algorithms. Moreover, it reacts more quickly and eliminates hot spots because of its full dynamic monitoring algorithm

Whole-genome sequence of <i>Pseudomonas fluorescens</i> EK007-RG4, a promising biocontrol agent against a broad range of bacteria, including the fire blight bacterium <i>Erwinia amylovora</i>

Here, we report the first draft whole-genome sequence of Pseudomonas fluorescens strain EK007-RG4, which was isolated from the phylloplane of a pear tree. P. fluorescens EK007-RG4 displays strong antagonism against Erwinia amylovora, the causal agent for fire blight disease, in addition to several other pathogenic and non-pathogenic bacteria

Plant Growth-Promoting Activity of Pseudomonas aeruginosa FG106 and Its Ability to Act as a Biocontrol Agent against Potato, Tomato and Taro Pathogens

Simple Summary Microbial bio-stimulants are attracting increasing attention in agricultural research. In particular, plant growth-promoting rhizobacteria (PGPR) have great potential to improve crops' productivity and tolerance of biotic and abiotic stresses. It is anticipated that PGPR could eventually replace synthetic fungicides in agriculture. This research evaluated Pseudomonas aeruginosa strain FG106-which was isolated from tomato plants- as a potential biocontrol agent against several plant pathogens. This strain displayed multiple plant growth-promoting attributes and high in vitro and in vivo inhibition of growth and pathogenicity of tested phytopathogens. It is thus a multifunctional PGPR with potential applications as a biocontrol agent to control fungal and bacterial pathogens. P. aeruginosa strain FG106 was isolated from the rhizosphere of tomato plants and identified through morphological analysis, 16S rRNA gene sequencing, and whole-genome sequencing. In vitro and in vivo experiments demonstrated that this strain could control several pathogens on tomato, potato, taro, and strawberry. Volatile and non-volatile metabolites produced by the strain are known to adversely affect the tested pathogens. FG106 showed clear antagonism against Alternaria alternata, Botrytis cinerea, Clavibacter michiganensis subsp. michiganensis, Phytophthora colocasiae, P. infestans, Rhizoctonia solani, and Xanthomonas euvesicatoria pv. perforans. FG106 produced proteases and lipases while also inducing high phosphate solubilization, producing siderophores, ammonia, indole acetic acid (IAA), and hydrogen cyanide (HCN) and forming biofilms that promote plant growth and facilitate biocontrol. Genome mining approaches showed that this strain harbors genes related to biocontrol and growth promotion. These results suggest that this bacterial strain provides good protection against pathogens of several agriculturally important plants via direct and indirect modes of action and could thus be a valuable bio-control agent

Phenotypic and Genome-Wide Analysis of an Antibiotic-Resistant Small Colony Variant (SCV) of Pseudomonas aeruginosa

Small colony variants (SCVs) are slow-growing bacteria, which often show increased resistance to antibiotics and cause latent or recurrent infections. It is therefore important to understand the mechanisms at the basis of this phenotypic switch.One SCV (termed PAO-SCV) was isolated, showing high resistance to gentamicin and to the cephalosporine cefotaxime. PAO-SCV was prone to reversion as evidenced by emergence of large colonies with a frequency of 10(-5) on media without antibiotics while it was stably maintained in presence of gentamicin. PAO-SCV showed a delayed growth, defective motility, and strongly reduced levels of the quorum sensing Pseudomonas quinolone signal (PQS). Whole genome expression analysis further suggested a multi-layered antibiotic resistance mechanism, including simultaneous over-expression of two drug efflux pumps (MexAB-OprM, MexXY-OprM), the LPS modification operon arnBCADTEF, and the PhoP-PhoQ two-component system. Conversely, the genes for the synthesis of PQS were strongly down-regulated in PAO-SCV. Finally, genomic analysis revealed the presence of mutations in phoP and phoQ genes as well as in the mexZ gene encoding a repressor of the mexXY and mexAB-oprM genes. Only one mutation occurred only in REV, at nucleotide 1020 of the tufA gene, a paralog of tufB, both encoding the elongation factor Tu, causing a change of the rarely used aspartic acid codon GAU to the more common GAC, possibly causing an increase of tufA mRNA translation. High expression of phoP and phoQ was confirmed for the SCV variant while the revertant showed expression levels reduced to wild-type levels.By combining data coming from phenotypic, gene expression and proteome analysis, we could demonstrate that resistance to aminoglycosides in one SCV mutant is multifactorial including overexpression of efflux mechanisms, LPS modification and is accompanied by a drastic down-regulation of the Pseudomonas quinolone signal quorum sensing system

The Role of Pathogenesis-Related Proteins in the Tomato-Rhizoctonia solani Interaction

Rhizoctonia solani is one of the most destructive pathogens causing foot rot disease on tomato. In this study, the molecular and cellular changes of a partially resistant (Sunny 6066) and a susceptible (Rio Grande) tomato cultivar after infection with necrotrophic soil-borne fungus R. solani were compared. The expression of defense-related genes such as chitinase (LOC544149) and peroxidase (CEVI-1) in infected tomato cultivars was investigated using semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). This method revealed elevated levels of expression for both genes in the partially resistant cultivar compared to the susceptible cultivar. One of the most prominent facets of basal plant defense responses is the formation of physical barriers at sites of attempted fungal penetration. These structures are produced around the sites of potential pathogen ingress to prevent pathogen progress in plant tissues. We investigated formation of lignin, as one of the most important structural barriers affecting plant resistance, using thioglycolic acid assay. A correlation was found between lignification and higher level of resistance in Sunny 6066 compared to Rio Grande cultivar. These findings suggest the involvement of chitinase, peroxidase, and lignin formation in defense responses of tomato plants against R. solani as a destructive pathogen

Effect of antimicrobial peptides and monoterpenes on control of fire blight

Aim of study: Antimicrobial peptides and monoterpenes are safe compounds that have been used for control of many plant diseases. Herein, the effects of two recombinant antibacterial peptides (AMPs) were compared with two monoterpenes for control of Erwinia amylovora directly or via induction of plant defense enzyme guaiacol peroxidase (GPOD).Area of study: The experiments were performed at the Ferdowsi University of Mashhad (Iran).Material and methods: The central composite design (CCD) method was used to study the effect of mixing the compounds and copper compound (Nordox) in controlling the pathogen. The resistance level was studied on shoots of tolerant (‘Dargazi’) and semi-susceptible (‘Spadona’) pear cultivars treated with the antibacterial compounds.Main results: Thanatin and 1,8-cineole showed the highest and lowest antibacterial effects. All treatments reduced E. amylovora pathogenicity on blossom. The CCD analysis revealed that the best reduction in colony number obtained by mixing Lfc, thanatin, thymol, 1,8-cineole and Nordox at concentrations of 32, 16, 24, 250 and 250 μg/mL. Thymol and 1,8-cineole at 500 μg/mL decreased disease severity significantly compared to that of AMPs. The level of GPOD enzyme in ‘Dargazi’ was higher than in ‘Spadona’. All treatments increased the GPOD levels in both cultivars. Furthermore, resistance level and GPOD ratio were negatively correlated.Research highlights: Antimicrobial peptides showed better effect on growth inhibition of E. amylovora than monoterpenes. Mixing of these peptides and monoterpens at special dosage enhanced their antimicrobial efficacy against E. amylovora; that could represent a new method in control of fire blight disease

Identification of epiphytic yeasts and bacteria with potential for biocontrol of grey mold disease on table grapes caused by Botrytis cinerea

The objective of this study was to identify grapevine epiphytic yeasts and bacteria for biocontrol of Botrytis cinerea on grapes. Antagonistic yeasts and bacteria were isolated from the epiphytic flora associated with grape berries and leaves cv. ‘Thompson seedless’ from vineyards in Iran and identified by sequencing the conserved genomic regions. A total of 130 yeast and bacterial isolates from the surface of grapevine were screened in vitro for determining their antagonistic effect against B. cinerea and used to control postharvest gray mold. Among the 130 isolates, five yeasts and four bacterial isolates showed the greatest antagonistic activity in vitro against B. cinerea. Two yeasts species including Meyerozyma guilliermondii and Candida membranifaciens had high antagonistic capability against the pathogen. Also, 4 bacterial isolates belonging to Bacillus sp. and Ralstonia sp. showed significant biocontrol effect against B. cinerea. The isolates were capable of producing volatile and non-volatile substances, which suppressed the pathogen growth. The antagonistic activity of selected yeasts and bacteria against the pathogen was investigated on wounded berries of ‘Thompson seedless’. On small clusters with intact berries, all of the antagonistic isolates considerably reduced the decay on grape berries and inhibition of gray mold incidence on fruits treated by these isolates was less than 50%, except for the isolate N1, which had higher capability in inhibiting the disease incidence. These results suggest that antagonist yeasts and bacteria with potential to control B. cinerea on grape can be found in the microflora of grape berries and leaves

Identification of epiphytic yeasts and bacteria with potential for biocontrol of grey mold disease on table grapes caused by Botrytis cinerea

The objective of this study was to identify grapevine epiphytic yeasts and bacteria for biocontrol of Botrytis cinerea on grapes. Antagonistic yeasts and bacteria were isolated from the epiphytic flora associated with grape berries and leaves cv. ‘Thompson seedless’ from vineyards in Iran and identified by sequencing the conserved genomic regions. A total of 130 yeast and bacterial isolates from the surface of grapevine were screened in vitro for determining their antagonistic effect against B. cinerea and used to control postharvest gray mold. Among the 130 isolates, five yeasts and four bacterial isolates showed the greatest antagonistic activity in vitro against B. cinerea. Two yeasts species including Meyerozyma guilliermondii and Candida membranifaciens had high antagonistic capability against the pathogen. Also, 4 bacterial isolates belonging to Bacillus sp. and Ralstonia sp. showed significant biocontrol effect against B. cinerea. The isolates were capable of producing volatile and non-volatile substances, which suppressed the pathogen growth. The antagonistic activity of selected yeasts and bacteria against the pathogen was investigated on wounded berries of ‘Thompson seedless’. On small clusters with intact berries, all of the antagonistic isolates considerably reduced the decay on grape berries and inhibition of gray mold incidence on fruits treated by these isolates was less than 50%, except for the isolate N1, which had higher capability in inhibiting the disease incidence. These results suggest that antagonist yeasts and bacteria with potential to control B. cinerea on grape can be found in the microflora of grape berries and leaves