Potential of different species of actinobacteria in the management of Meloidogyne javanica.

Root-knot nematodes (RKN) are one of the most harmful soil-borne plant pathogens in the world. Actinobacteria are known phytopathogen control agents. The aim of this study was to select soil actinobacteria with control potential against the RKN (Meloidogyne javanica) in tomato plants and to determine mechanisms of action. Ten isolates were tested and a significant reduction was observed in the number of M. javanica eggs, and galls 46 days after infestation with the nematode. The results could be explained by the combination of different mechanisms including parasitism and induction of plant defense response. The M. javanica eggs were parasited by all isolates tested. Some isolates reduced the penetration of juveniles into the roots. Other isolates using the split-root method were able to induce systemic defenses in tomato plants. The 4L isolate was selected for analysis of the expression of the plant defense genes TomLoxA, ACCO, PR1, and RBOH1. In plants treated with 4L isolate and M. javanica, there was a significant increase in the number of TomLoxA and ACCO gene transcripts. In plants treated only with M. javanica, only the expression of the RBOH1 and PR1 genes was induced in the first hours after infection. The isolates were identified using 16S rRNA gene sequencing as Streptomyces sp. (1A, 3F, 4L, 6O, 8S, 9T, and 10U), Kribbella sp. (5N), Kitasatospora sp. (2AE), and Lentzea sp. (7P). The efficacy of isolates from the Kitasatospora, Kribbella, and Lentzea genera was reported for the first time, and the efficacy of Streptomyces genus isolates for controlling M. javanica was confirmed. All the isolates tested in this study were efficient against RKN. This study provides the opportunity to investigate bacterial genera that have not yet been explored in the control of M. javanica in tomatoes and other crops.

Pectinolytic arsenal of Colletotrichum lindemuthianum and other fungi with different lifestyles.

AIM: To identify and analyse genes that encode pectinases in the genome of the fungus Colletotrichum lindemuthianum, evaluate the expression of these genes, and compare putative pectinases found in C. lindemuthianum with pectinases produced by other fungi and oomycetes with different lifestyles. METHODS AND RESULTS: Genes encoding pectinases in the genome of C. lindemuthianum were identified and analysed. The expression of these genes was analysed. Pectinases from C. lindemuthianum were compared with pectinases from other fungi that have different lifestyles, and the pectinase activity in some of these fungi was quantified. Fifty-eight genes encoding pectinases were identified in C. lindemuthianum. At least six types of enzymes involved in pectin degradation were identified, with pectate lyases and polygalacturonases being the most abundant. Twenty-seven genes encoding pectinases were differentially expressed at some point in C. lindemuthianum during their interactions with their host. For each type of pectinase, there were at least three isoenzyme groups. The number of pectinases present in fungi with different lifestyles seemed to be related more to the lifestyle than to the taxonomic relationship between them. Only phytopathogenic fungi showed pectate lyase activity. CONCLUSIONS: The collective results demonstrate the pectinolytic arsenal of C. lindemuthianum, with many and diverse genes encoding pectinases more than that found in other phytopathogens, which suggests that at least part of these pectinases must be important for the pathogenicity of the fungus C. lindemuthianum. SIGNIFICANCE AND IMPACT OF THE STUDY: Knowledge of these pectinases could further the understanding of the importance of this broad pectinolytic arsenal in the common bean infection and could be exploited for biotechnological purposes.

Colletotrichum: species complexes, lifestyle, and peculiarities of some sources of genetic variability.

The genus Colletotrichum comprises species with different lifestyles but is mainly known for phytopathogenic species that infect crops of agronomic relevance causing considerable losses. The fungi of the genus Colletotrichum are distributed in species complexes and within each complex some species have particularities regarding their lifestyle. The most commonly found and described lifestyles in Colletotrichum are endophytic and hemibiotrophic phytopathogenic. Several of these phytopathogenic species show wide genetic variability, which makes long-term maintenance of resistance in plants difficult. Different mechanisms may play an important role in the emergence of genetic variants but are not yet fully understood in this genus. These mechanisms include heterokaryosis, a parasexual cycle, sexual cycle, transposable element activity, and repeat-induced point mutations. This review provides an overview of the genus Colletotrichum, the species complexes described so far and the most common lifestyles in the genus, with a special emphasis on the mechanisms that may be responsible, at least in part, for the emergence of new genotypes under field conditions.

The repertoire of effector candidates in Colletotrichum lindemuthianum reveals important information about Colletotrichum genus lifestyle.

The fungus Colletotrichum lindemuthianum is the causal agent of anthracnose in the common bean (Phaseolus vulgaris), and anthracnose is one of the most devastating diseases of this plant species. However, little is known about the proteins that are essential for the fungus-plant interactions. Knowledge of the fungus' arsenal of effector proteins is of great importance for understanding this pathosystem. In this work, we analyzed for the first time the arsenal of Colletotrichum lindemuthianum effector candidates (ClECs) and compared them with effector proteins from other species of the genus Colletotrichum, providing a valuable resource for studying the infection mechanisms of these pathogens in their hosts. Isolates of two physiological races (83.501 and 89 A2 2-3) of C. lindemuthianum were used to predict 353 and 349 ClECs, respectively. Of these ClECs, 63% were found to be rich in cysteine, have repetitive sequences of amino acids, and/or possess nuclear localization sequences. Several conserved domains were found between the ClECs. We also applied the effector prediction to nine species in the genus Colletotrichum, and the results ranged from 247 predicted effectors in Colletotrichum graminicola to 446 in Colletotrichum orbiculare. Twelve conserved domains were predicted in the effector candidates of all analyzed species of Colletotrichum. An expression analysis of the eight genes encoding the effector candidates in C. lindemuthianum revealed their induction during the biotrophic phase of the fungus on the bean.

Comparative analysis of the mitochondrial genome of the fungus Colletotrichum lindemuthianum, the causal agent of anthracnose in common beans.

Fungi of the genus Colletotrichum are economically important and are used as models in plant-pathogen interaction studies. In this study, the complete mitochondrial genomes of two Colletotrichum lindemuthianum isolates were sequenced and compared with the mitochondrial genomes of seven species of Colletotrichum. The mitochondrial genome of C. lindemuthianum is a typical circular molecule 37,446 bp (isolate 89 A2 2-3) and 37,440 bp (isolate 83.501) in length. The difference of six nucleotides between the two genomes is the result of a deletion in the ribosomal protein S3 (rps3) gene in the 83.501 isolate. In addition, substitution of adenine for guanine within the rps3 gene in the mitochondrial genome of the 83.501 isolate was observed. Compared to the previously sequenced C. lindemuthianum mitochondrial genome, an exon no annotated in the cytochrome c oxidase I (cox1) gene and a non-conserved open reading frame (ncORF) were observed. The size of the mitochondrial genomes of the seven species of Colletotrichum was highly variable, being attributed mainly to the ncORF, ranging from one to 10 and also from introns ranging from one to 11 and which encode a total of up to nine homing endonucleases. This paper reports for the first time by means of transcriptome that then ncORFs are transcribed in Colletotrichum spp. Phylogeny data revealed that core mitochondrial genes could be used as an alternative in phylogenetic relationship studies in Colletotrichum spp. This work contributes to the genetic and biological knowledge of Colletotrichum spp., which is of great economic and scientific importance.

A look into a multifunctional toolbox: endophytic Bacillus species provide broad and underexploited benefits for plants.

One of the major challenges of agriculture currently is to obtain higher crop yield. Environmental conditions, cultivar quality, and plant diseases greatly affect plant productivity. On the other hand, several endophytic Bacillus species have emerged as a complementary, efficient, and safe alternative to current crop management practices. The ability of Bacillus species to form spores, which resist adverse conditions, is an advantage of the genus for use in formulations. Endophytic Bacillus species provide plants with a wide range of benefits, including protection against phytopathogenic microorganisms, insects, and nematodes, eliciting resistance, and promoting plant growth, without causing damage to the environment. Bacillus thuringiensis, B. subtilis, B. amyloliquefaciens, B. velezensis, B. cereus, B. pumilus, and B. licheniformis are the most studied Bacillus species for application in agriculture, although other species within the genus have also shown great potential. Due to the increasing number of whole-genome sequenced endophytic Bacillus spp. strains, various bioactive compounds have been predicted. These data reveal endophytic Bacillus species as an underexploited source of novel molecules of biotechnological interest. In this review, we discuss how endophytic Bacillus species are a valuable multifunctional toolbox to be integrated with crop management practices for achieving higher crop yield.

Endophytic Bacteria Isolated from Common Bean (Phaseolus vulgaris) Exhibiting High Variability Showed Antimicrobial Activity and Quorum Sensing Inhibition.

Endophytic bacteria play a key role in the biocontrol of phytopathogenic microorganisms. In this study, genotypic diversity was analyzed via repetitive element PCR (rep-PCR) of endophytic isolates of the phylum Actinobacteria that were previously collected from leaves of cultivars of common bean (Phaseolus vulgaris). Considerable variability was observed, which has not been reported previously for this phylum of endophytic bacteria of the common bean. Furthermore, the ethanol extracts from cultures of various isolates inhibited the growth of pathogenic bacteria in vitro, especially Gram-positive pathogens. Extracts from cultures of Microbacterium testaceum BAC1065 and BAC1093, which were both isolated from the 'Talismã' cultivar, strongly inhibited most of the pathogenic bacteria tested. Bean endophytic bacteria were also demonstrated to have the potential to inhibit the quorum sensing of Gram-negative bacteria. This mechanism may regulate the production of virulence factors in pathogens. The ability to inhibit quorum sensing has also not been reported previously for endophytic microorganisms of P. vulgaris. Furthermore, M. testaceum with capacity to inhibit quorum sensing appears to be widespread in common bean. The genomic profiles of M. testaceum were also analyzed via pulsed-field gel electrophoresis, and greater differentiation was observed using this method than rep-PCR; in general, no groups were formed based on the cultivar of origin. This study showed for the first time that endophytic bacteria from common bean plants exhibit high variability and may be useful for the development of strategies for the biological control of diseases in this important legume plant.

Use of the IRAP marker to study genetic variability in Pseudocercospora fijiensis populations.

Pseudocercospora fijiensis is the etiological agent of black Sigatoka, which is currently considered as one of the most destructive banana diseases in all locations where it occurs. It is estimated that a large portion of the P. fijiensis genome consists of transposable elements, which allows researchers to use transposon-based molecular markers in the analysis of genetic variability in populations of this pathogen. In this context, the inter-retrotransposon-amplified polymorphism (IRAP) was used to study the genetic variability in P. fijiensis populations from different hosts and different geographical origins in Brazil. A total of 22 loci were amplified and 77.3 % showed a polymorphism. Cluster analysis revealed two major groups in Brazil. The observed genetic diversity (H E) was 0.22, and through molecular analysis of variance, it was determined that the greatest genetic variability occurs within populations. The discriminant analysis of principal components revealed no structuring related to the geographical origin of culture of the host. The IRAP-based marker system is a suitable tool for the study of genetic variability in P. fijiensis.

Genome organization and assessment of high copy number and increased expression of pectinolytic genes from Penicillium griseoroseum: a potential heterologous system for protein production.

The fungus Penicillium griseoroseum has the potential for application on an industrial scale as a host for the production of homologous and heterologous proteins, mainly because it does not produce some mycotoxins or secrete proteases under the growth conditions for pectinase production. However, for the fungus to be used effectively as an expression heterologous system, an understanding of the organization of its genome, as well as the mechanisms of gene expression and protein production, is required. In the present study, the size of the P. griseoroseum genome was estimated to be 29.8-31.5 Mb, distributed among four chromosomes. An analysis of plg1 and pgg2 pectinolytic genes expression and copy number in recombinant multi-copy strains of P. griseoroseum demonstrated that an increase in the number of gene copies could increase enzyme production, but the transcription could be affected by the gene integration position. Placing a copy of the plg1 gene under the control of the gpd promoter of Aspergillus nidulans yielded a 200-fold increase in transcription levels compared to the endogenous gene, and two copies of the pgg2 gene produced an 1100-fold increase compared with the endogenous gene. These results demonstrated that transcription, translation, and protein secretion in the fungus P. griseoroseum respond to an increased number of gene copies in the genome. The processing capacity and efficiency of protein secretion in P. griseoroseum are consistent with our premise that this fungus can be used for the industrial-scale production of several enzymes.

Transposable elements belonging to the Tc1-Mariner superfamily are heavily mutated in Colletotrichum graminicola.

Transposable elements are ubiquitous and constitute an important source of genetic variation in addition to generating deleterious mutations. Several filamentous fungi are able to defend against transposable elements using RIP(repeat-induced point mutation)-like mechanisms, which induce mutations in duplicated sequences. The sequenced Colletotrichum graminicola genome and the availability of transposable element databases provide an efficient approach for identifying and characterizing transposable elements in this fungus, which was the subject of this study. We identified 132 full-sized Tc1-Mariner transposable elements in the sequenced C. graminicola genome, which were divided into six families. Several putative transposases that have been found in these elements have conserved DDE motifs, but all are interrupted by stop codons. An in silico analysis showed evidence for RIP-generated mutations. The TCg1 element, which was cloned from the Brazilian 2908 m isolate, has a putative transposase sequence with three characteristic conserved motifs. However, this sequence is interrupted by five stop codons. Genomic DNA from various isolates was analyzed by hybridization with an internal region of TCg1. All of the isolates featured transposable elements that were similar to TCg1, and several hybridization profiles were identified. C. graminicola has many Tc1-Mariner transposable elements that have been degenerated by characteristic RIP mutations. It is unlikely that any of the characterized elements are autonomous in the sequenced isolate. The possible existence of active copies in field isolates from Brazil was shown. The TCg1 element is present in several C. graminicola isolates and is a potentially useful molecular marker for population studies of this phytopathogen.

pH-dependent effect of pectinase secretion in Penicillium griseoroseum recombinant strains.

A number of parameters, including culture medium pH, affect growth and enzyme production by microorganisms. In the present study, the production and secretion of pectin lyase (PL) and polygalacturonase (PG) by recombinant strains of Penicillium griseoroseum cultured in mineral-buffered media (MBM; initial pH 6.8) and mineral-unbuffered medium (MUM; initial pH 6.3) were evaluated. Under these culture conditions, no change in the transcriptional levels of plg1 and pgg2 was observed. However, the levels of secreted total protein ranged from 7.80 ± 1.1 to 3.25 ± 1.50 µg ml(-1) in MBM and MUM, respectively, and were evaluated by SDS-PAGE. PL and PG enzymatic activities decreased 6.4 and 3.6 times, respectively, when P. griseoroseum was cultivated under acidic pH conditions (MUM). Furthermore, differences were observed in the hypha and mycelium morphology. These findings suggest that acidic growing conditions affect PL and PG secretion, even though the transcription and translation processes are successful. The data obtained in this study will help to establish optimal culture conditions that increase production and secretion of recombinant proteins by filamentous fungi.

In vitro Scleroderma laeve and Eucalyptus grandis mycorrhization and analysis of atp6, 17S rDNA, and ras gene expression during ectomycorrhizal formation.

The interaction between fungi and plants that form ectomycorrhizae (ECM) promotes alterations in the gene expression profiles of both organisms. Fungal genes expression related to metabolism were evaluated at the pre-symbiotic stage and during the ECM development between Scleroderma laeve and Eucalyptus grandis. Partial sequences of ATP synthase (atp6), translation elongation factor (ef1α), the RAS protein (ras), and the 17S rDNA genes were isolated. The expression of the atp6 and 17S rDNA genes during the pre-symbiotic stage showed an approximately threefold increase compared to the control. During ECM development, the expression of the 17S rDNA gene showed a 4.4-fold increase after 3 days of contact, while the expression of the atp6 gene increased 7.23-fold by the 15th day, suggesting that protein synthesis and respiratory chain activities are increased during the formation of the mantle and the Hartig net. The ras gene transcripts were only detected by RT-PCR 30 days after fungus-plant contact, suggesting that RAS-mediated signal transduction pathways are functional during the establishment of symbiosis. The present study demonstrates that alterations in gene expression occur in response to stimuli released by the plant during ECM association and increases the understanding of the association between S. laeve and E. grandis.

Bacillus velezensis iturins inhibit the hemolytic activity of Staphylococcus aureus.

Bovine mastitis caused by S. aureus has a major economic impact on the dairy sector. With the crucial need for new therapies, anti-virulence strategies have gained attention as alternatives to antibiotics. Here we aimed to identify novel compounds that inhibit the production/activity of hemolysins, a virulence factor of S. aureus associated with mastitis severity. We screened Bacillus strains obtained from diverse sources for compounds showing anti-hemolytic activity. Our results demonstrate that lipopeptides produced by Bacillus spp. completely prevented the hemolytic activity of S. aureus at certain concentrations. Following purification, both iturins, fengycins, and surfactins were able to reduce hemolysis caused by S. aureus, with iturins showing the highest anti-hemolytic activity (up to 76% reduction). The lipopeptides showed an effect at the post-translational level. Molecular docking simulations demonstrated that these compounds can bind to hemolysin, possibly interfering with enzyme action. Lastly, molecular dynamics analysis indicated general stability of important residues for hemolysin activity as well as the presence of hydrogen bonds between iturins and these residues, with longevous interactions. Our data reveals, for the first time, an anti-hemolytic activity of lipopeptides and highlights the potential application of iturins as an anti-virulence therapy to control bovine mastitis caused by S. aureus.

Boto, a class II transposon in Moniliophthora perniciosa, is the first representative of the PIF/Harbinger superfamily in a phytopathogenic fungus.

Boto, a class II transposable element, was characterized in the Moniliophthora perniciosa genome. The Boto transposase is highly similar to plant PIF-like transposases that belong to the newest class II superfamily known as PIF/Harbinger. Although Boto shares characteristics with PIF-like elements, other characteristics, such as the transposase intron position, the position and direction of the second ORF, and the footprint, indicate that Boto belongs to a novel family of the PIF/Harbinger superfamily. Southern blot analyses detected 6-12 copies of Boto in C-biotype isolates and a ubiquitous presence among the C- and S-biotypes, as well as a separation in the C-biotype isolates from Bahia State in Brazil in at least two genotypic groups, and a new insertion in the genome of a C-biotype isolate maintained in the laboratory for 6 years. In addition to PCR amplification from a specific insertion site, changes in the Boto hybridization profile after the M. perniciosa sexual cycle and detection of Boto transcripts gave further evidence of Boto activity. As an active family in the genome of M. perniciosa, Boto elements may contribute to genetic variability in this homothallic fungus. This is the first report of a PIF/Harbinger transposon in the genome of a phytopathogenic fungus.

Terminal repeat retrotransposons as DNA markers in fungi.

In this study, we demonstrate that ClIRAP primers designed using the transposable element RetroCl1 sequence from Colletotrichum lindemuthianum can be used to generate an efficient IRAP (inter-retrotransposon amplified polymorphism) molecular marker to study intra- and inter-species diversity in fungi. It has been previously demonstrated that primers generated from this TRIM-like element can be used in the Colletotrichum species. We now prove that the RetroCl1 sequence can also be used to analyze diversity in different fungi. IRAP profiles were successfully generated for 27 fungi species from 11 different orders, and intra-species genetic variability was detected in six species. The ClIRAP primers facilitate the use of the IRAP technique for a variety of fungi without prior knowledge of the genome.

Characterization of the omlA gene from different serotypes of Actinobacillus pleuropneumoniae: A new insight into an old approach.

The OmlA protein is a virulence factor of Actinobacillus pleuropneumoniae, an important pathogen in pigs. The polymorphisms present in the omlA gene sequence of 15 reference serotypes of A. pleuropneumoniae and non-serotypable isolates were assessed to determine the possible evolutionary relationship among them and to validate the importance of this gene as a molecular marker for the characterization of this bacterium. Divergence among the 15 serotypes of A. pleuropneumoniae probably resulted initially from two major evolutionary events that led to subsequent differentiation into nine groups. This differentiation makes it possible to characterize most of the serotypes by using bionformatics, thereby avoiding problems with immunological cross-reactivity. A conserved α-helix common to all the serotypes was most likely involved in connecting the protein to the outer membrane and acting as a signal peptide. A previously unknown gene duplication was also identified and could contribute to the genetic variability that makes it difficult to serotype some isolates. Our data support the importance of the omlA gene in the biology of A. pleuropneumoniae and provide a new area of research into the OmlA protein.

Endophytic Trichoderma species from rubber trees native to the Brazilian Amazon, including four new species.

Fungi belonging to the genus Trichoderma have been widely recognized as efficient controllers of plant diseases. Although the majority of isolates currently deployed, thus far, have been isolated from soil, endophytic Trichoderma spp. is considered to be a promising option for application in biocontrol. In this study, 30 endophytic Trichoderma isolates-obtained from the leaves, stems, and roots of wild Hevea spp. in the Brazilian Amazon-were analyzed using specific DNA barcodes: sequences of internal transcribed spacers 1 and 2 of rDNA (ITS region), genes encoding translation elongation factor 1-α (TEF1-α), and the second largest subunit of RNA polymerase II (RPB2). The genealogical concordance phylogenetic species recognition (GCPSR) concept was used for species delimitation. A phylogenetic analysis showed the occurrence of Trichoderma species, such as T. erinaceum, T. ovalisporum, T. koningiopsis, T. sparsum, T. lentiforme, T. virens, and T. spirale. Molecular and morphological features resulted in the discovery of four new species, such as T. acreanum sp. nov., T. ararianum sp. nov., T. heveae sp. nov., and T. brasiliensis sp. nov. The BI and ML analyses shared a similar topology, providing high support to the final trees. The phylograms show three distinct subclades, namely, T. acreanum and T. ararianum being paraphyletic with T. koningiopsis; T. heveae with T. subviride; and T. brasiliensis with T. brevicompactum. This study adds to our knowledge of the diversity of endophytic Trichoderma species in Neotropical forests and reveals new potential biocontrol agents for the management of plant diseases.

Development of new molecular markers for the Colletotrichum genus using RetroCl1 sequences.

A nonautonomous element of 624 bp, called RetroCl1 (Retroelement Colletotrichum lindemuthianum 1), was identified in the plant pathogenic fungus Colletotrichum lindemuthianum. RetroCl1 contains terminal direct repeats (223 bp) that are surrounded by CTAGT sequences. It has a short internal domain of 178 bp and shows characteristics of terminal-repeat retrotransposon in miniature (TRIM) family. We used RetroCl1 sequence to develop molecular markers for the Colletotrichum genus. IRAP (Inter-Retrotransposon Amplified Polymorphism) and REMAP (Retrotransposon-Microsatellite Amplified Polymorphism) markers were used to analyze the genetic diversity of C. lindemuthianum. Fifty-four isolates belonging to different races were used. A total of 45 loci were amplified. The Nei index showed significant differences among the populations divided according to race, indicating that they are structured according to pathotype. No clear correlation between IRAP and REMAP markers with pathogenic characterization was found. C. lindemuthianum has high genetic diversity, and the analysis of molecular variance showed that 51% of variability is found among the populations of different races. The markers were also tested in different Colletotrichum species. In every case, multiple bands were amplified, indicating that these markers can be successfully used in different species belonging to the Colletotrichum genus.

Isolation and characterization of endophytic bacteria isolated from the leaves of the common bean (Phaseolus vulgaris).

The common bean is one of the most important legumes in the human diet, but little is known about the endophytic bacteria associated with the leaves of this plant. The objective of this study was to characterize the culturable endophytic bacteria of common bean (Phaseolus vulgaris) leaves from three different cultivars (Vermelhinho, Talismã, and Ouro Negro) grown under the same field conditions. The density of endophytic populations varied from 4.5 x 10(2) to 2.8 x 10(3) CFU g(-1) of fresh weight. Of the 158 total isolates, 36.7% belonged to the Proteobacteria, 32.9% to Firmicutes, 29.7% to Actinobacteria, and 0.6% to Bacteroidetes. The three P. vulgaris cultivars showed class distribution differences among Actinobacteria, Alphaproteobacteria and Bacilli. Based on 16S rDNA sequences, 23 different genera were isolated comprising bacteria commonly associated with soil and plants. The genera Bacillus, Delftia, Methylobacterium, Microbacterium, Paenibacillus, Staphylococcus and Stenotrophomonas were isolated from all three cultivars. To access and compare the community structure, diversity indices were calculated. The isolates from the Talismã cultivar were less diverse than the isolates derived from the other two cultivars. The results of this work indicate that the cultivar of the plant may contribute to the structure of the endophytic community associated with the common bean. This is the first report of endophytic bacteria from the leaves of P. vulgaris cultivars. Future studies will determine the potential application of these isolates in biological control, growth promotion and enzyme production for biotechnology.

Genomic analysis reveals the role of integrative and conjugative elements in plant pathogenic bacteria.

BACKGROUND: ICEs are mobile genetic elements found integrated into bacterial chromosomes that can excise and be transferred to a new cell. They play an important role in horizontal gene transmission and carry accessory genes that may provide interesting phenotypes for the bacteria. Here, we seek to research the presence and the role of ICEs in 300 genomes of phytopathogenic bacteria with the greatest scientific and economic impact. RESULTS: Seventy-eight ICEs (45 distinct elements) were identified and characterized in chromosomes of Agrobacterium tumefaciens, Dickeya dadantii, and D. solani, Pectobacterium carotovorum and P. atrosepticum, Pseudomonas syringae, Ralstonia solanacearum Species Complex, and Xanthomonas campestris. Intriguingly, the co-occurrence of four ICEs was observed in some P. syringae strains. Moreover, we identified 31 novel elements, carrying 396 accessory genes with potential influence on virulence and fitness, such as genes coding for functions related to T3SS, cell wall degradation and resistance to heavy metals. We also present the analysis of previously reported data on the expression of cargo genes related to the virulence of P. atrosepticum ICEs, which evidences the role of these genes in the infection process of tobacco plants. CONCLUSIONS: Altogether, this paper has highlighted the potential of ICEs to affect the pathogenicity and lifestyle of these phytopathogens and direct the spread of significant putative virulence genes in phytopathogenic bacteria.