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Epicoccum nigrum P16, a sugarcane endophyte, produces antifungal compounds and induces root growth.

Fávaro LC, Sebastianes FL, Araújo WL - PLoS ONE (2012)

Bottom Line: We report an approach based on inoculation followed by re-isolation, molecular monitoring, microscopic analysis, plant growth responses to fungal colonization, and antimicrobial activity tests to study the basic aspects of the E. nigrum endophytic interaction with sugarcane, and the effects of colonization on plant physiology.The results indicate that E. nigrum was capable of increasing the root system biomass and producing compounds that inhibit the in vitro growth of sugarcane pathogens Fusarium verticillioides, Colletotrichum falcatum, Ceratocystis paradoxa, and Xanthomomas albilineans.In addition, this work contributes to the knowledge of the interaction of this ubiquitous endophyte with the host plant, and also to a better use of microbial endophytes in agriculture.

View Article: PubMed Central - PubMed

Affiliation: Brazilian Agricultural Research Corporation, Embrapa Agroenergia, Brasília, Distrito Federal, Brazil. leia.favaro@embrapa.br

ABSTRACT

Background: Sugarcane is one of the most important crops in Brazil, mainly because of its use in biofuel production. Recent studies have sought to determine the role of sugarcane endophytic microbial diversity in microorganism-plant interactions, and their biotechnological potential. Epicoccum nigrum is an important sugarcane endophytic fungus that has been associated with the biological control of phytopathogens, and the production of secondary metabolites. In spite of several studies carried out to define the better conditions to use E. nigrum in different crops, little is known about the establishment of an endophytic interaction, and its potential effects on plant physiology.

Methodology/principal findings: We report an approach based on inoculation followed by re-isolation, molecular monitoring, microscopic analysis, plant growth responses to fungal colonization, and antimicrobial activity tests to study the basic aspects of the E. nigrum endophytic interaction with sugarcane, and the effects of colonization on plant physiology. The results indicate that E. nigrum was capable of increasing the root system biomass and producing compounds that inhibit the in vitro growth of sugarcane pathogens Fusarium verticillioides, Colletotrichum falcatum, Ceratocystis paradoxa, and Xanthomomas albilineans. In addition, E. nigrum preferentially colonizes the sugarcane surface and, occasionally, the endophytic environment.

Conclusions/significance: Our work demonstrates that E. nigrum has great potential for sugarcane crop application because it is capable of increasing the root system biomass and controlling pathogens. The study of the basic aspects of the interaction of E. nigrum with sugarcane demonstrated the facultative endophytism of E. nigrum and its preference for the phylloplane environment, which should be considered in future studies of biocontrol using this species. In addition, this work contributes to the knowledge of the interaction of this ubiquitous endophyte with the host plant, and also to a better use of microbial endophytes in agriculture.

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Related in: MedlinePlus

Antimicrobial activity of the ethyl acetate extract from E. nigrum P16 endophytic strain.Antifungal and anti-oomycete activity of the ethyl acetate extract from E. nigrum P16 strain. The percentage of growth inhibition of the pathogens is showed in the y axis. The means of three replicates for each extract concentration analysed were used to calculate the percent reduction in pathogen mycelial growth by the equation [1– (mean colony diameter of the control/mean colony diameter of the treatment)×100].
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pone-0036826-g005: Antimicrobial activity of the ethyl acetate extract from E. nigrum P16 endophytic strain.Antifungal and anti-oomycete activity of the ethyl acetate extract from E. nigrum P16 strain. The percentage of growth inhibition of the pathogens is showed in the y axis. The means of three replicates for each extract concentration analysed were used to calculate the percent reduction in pathogen mycelial growth by the equation [1– (mean colony diameter of the control/mean colony diameter of the treatment)×100].

Mentions: Because we observed that diffusible compounds were produced during E. nigrum growth in solid medium, we also investigated if the organic extracts of the supernatant (ethyl acetate) and the mycelium (methanol) of the E. nigrum culture had inhibitory activity. The extract obtained from the mycelium did not exhibit antimicrobial activity under the assessment conditions, possibly because the compounds were not stored in the mycelia or their production was low and their presence could not be detected by the methods used. However, the ethyl acetate extract inhibited X.albilineans growth (Figure 4f–h) and produced a 15.5 mm (±0.1 mm) inhibition zone; the inhibition zone produced by the antibiotic spectinomycin, which was used as a positive control, was 19.0 mm (±0.1 mm). The E. nigrum extract also significantly reduced C.falcatum, F. verticillioides, C. paradoxa and Phythophthora sp. growth at concentrations ranging from 0.1 to 2.0 mg.mL−1. C. falcatum and Phythophthora sp. were more sensitive to the extract, with colony diameter reductions of 75% and 76.47%, respectively, in the presence of 2.0 mg.mL−1 of the extract (Figure 5).


Epicoccum nigrum P16, a sugarcane endophyte, produces antifungal compounds and induces root growth.

Fávaro LC, Sebastianes FL, Araújo WL - PLoS ONE (2012)

Antimicrobial activity of the ethyl acetate extract from E. nigrum P16 endophytic strain.Antifungal and anti-oomycete activity of the ethyl acetate extract from E. nigrum P16 strain. The percentage of growth inhibition of the pathogens is showed in the y axis. The means of three replicates for each extract concentration analysed were used to calculate the percent reduction in pathogen mycelial growth by the equation [1– (mean colony diameter of the control/mean colony diameter of the treatment)×100].
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3366970&req=5

pone-0036826-g005: Antimicrobial activity of the ethyl acetate extract from E. nigrum P16 endophytic strain.Antifungal and anti-oomycete activity of the ethyl acetate extract from E. nigrum P16 strain. The percentage of growth inhibition of the pathogens is showed in the y axis. The means of three replicates for each extract concentration analysed were used to calculate the percent reduction in pathogen mycelial growth by the equation [1– (mean colony diameter of the control/mean colony diameter of the treatment)×100].
Mentions: Because we observed that diffusible compounds were produced during E. nigrum growth in solid medium, we also investigated if the organic extracts of the supernatant (ethyl acetate) and the mycelium (methanol) of the E. nigrum culture had inhibitory activity. The extract obtained from the mycelium did not exhibit antimicrobial activity under the assessment conditions, possibly because the compounds were not stored in the mycelia or their production was low and their presence could not be detected by the methods used. However, the ethyl acetate extract inhibited X.albilineans growth (Figure 4f–h) and produced a 15.5 mm (±0.1 mm) inhibition zone; the inhibition zone produced by the antibiotic spectinomycin, which was used as a positive control, was 19.0 mm (±0.1 mm). The E. nigrum extract also significantly reduced C.falcatum, F. verticillioides, C. paradoxa and Phythophthora sp. growth at concentrations ranging from 0.1 to 2.0 mg.mL−1. C. falcatum and Phythophthora sp. were more sensitive to the extract, with colony diameter reductions of 75% and 76.47%, respectively, in the presence of 2.0 mg.mL−1 of the extract (Figure 5).

Bottom Line: We report an approach based on inoculation followed by re-isolation, molecular monitoring, microscopic analysis, plant growth responses to fungal colonization, and antimicrobial activity tests to study the basic aspects of the E. nigrum endophytic interaction with sugarcane, and the effects of colonization on plant physiology.The results indicate that E. nigrum was capable of increasing the root system biomass and producing compounds that inhibit the in vitro growth of sugarcane pathogens Fusarium verticillioides, Colletotrichum falcatum, Ceratocystis paradoxa, and Xanthomomas albilineans.In addition, this work contributes to the knowledge of the interaction of this ubiquitous endophyte with the host plant, and also to a better use of microbial endophytes in agriculture.

View Article: PubMed Central - PubMed

Affiliation: Brazilian Agricultural Research Corporation, Embrapa Agroenergia, Brasília, Distrito Federal, Brazil. leia.favaro@embrapa.br

ABSTRACT

Background: Sugarcane is one of the most important crops in Brazil, mainly because of its use in biofuel production. Recent studies have sought to determine the role of sugarcane endophytic microbial diversity in microorganism-plant interactions, and their biotechnological potential. Epicoccum nigrum is an important sugarcane endophytic fungus that has been associated with the biological control of phytopathogens, and the production of secondary metabolites. In spite of several studies carried out to define the better conditions to use E. nigrum in different crops, little is known about the establishment of an endophytic interaction, and its potential effects on plant physiology.

Methodology/principal findings: We report an approach based on inoculation followed by re-isolation, molecular monitoring, microscopic analysis, plant growth responses to fungal colonization, and antimicrobial activity tests to study the basic aspects of the E. nigrum endophytic interaction with sugarcane, and the effects of colonization on plant physiology. The results indicate that E. nigrum was capable of increasing the root system biomass and producing compounds that inhibit the in vitro growth of sugarcane pathogens Fusarium verticillioides, Colletotrichum falcatum, Ceratocystis paradoxa, and Xanthomomas albilineans. In addition, E. nigrum preferentially colonizes the sugarcane surface and, occasionally, the endophytic environment.

Conclusions/significance: Our work demonstrates that E. nigrum has great potential for sugarcane crop application because it is capable of increasing the root system biomass and controlling pathogens. The study of the basic aspects of the interaction of E. nigrum with sugarcane demonstrated the facultative endophytism of E. nigrum and its preference for the phylloplane environment, which should be considered in future studies of biocontrol using this species. In addition, this work contributes to the knowledge of the interaction of this ubiquitous endophyte with the host plant, and also to a better use of microbial endophytes in agriculture.

Show MeSH
Related in: MedlinePlus