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Diversity and Activity of Lysobacter Species from Disease Suppressive Soils.

Gómez Expósito R, Postma J, Raaijmakers JM, De Bruijn I - Front Microbiol (2015)

Bottom Line: In conclusion, our results demonstrated that Lysobacter species have strong antagonistic activities against a range of pathogens, making them an important source for putative new enzymes and antimicrobial compounds.However, their potential role in R. solani disease suppressive soil could not be confirmed.In-depth omics'-based analyses will be needed to shed more light on the potential contribution of Lysobacter species to the collective activities of microbial consortia in disease suppressive soils.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW) Wageningen, Netherlands ; Laboratory of Phytopathology, Wageningen University and Research Centre Wageningen, Netherlands.

ABSTRACT
The genus Lysobacter includes several species that produce a range of extracellular enzymes and other metabolites with activity against bacteria, fungi, oomycetes, and nematodes. Lysobacter species were found to be more abundant in soil suppressive against the fungal root pathogen Rhizoctonia solani, but their actual role in disease suppression is still unclear. Here, the antifungal and plant growth-promoting activities of 18 Lysobacter strains, including 11 strains from Rhizoctonia-suppressive soils, were studied both in vitro and in vivo. Based on 16S rRNA sequencing, the Lysobacter strains from the Rhizoctonia-suppressive soil belonged to the four species Lysobacter antibioticus, Lysobacter capsici, Lysobacter enzymogenes, and Lysobacter gummosus. Most strains showed strong in vitro activity against R. solani and several other pathogens, including Pythium ultimum, Aspergillus niger, Fusarium oxysporum, and Xanthomonas campestris. When the Lysobacter strains were introduced into soil, however, no significant and consistent suppression of R. solani damping-off disease of sugar beet and cauliflower was observed. Subsequent bioassays further revealed that none of the Lysobacter strains was able to promote growth of sugar beet, cauliflower, onion, and Arabidopsis thaliana, either directly or via volatile compounds. The lack of in vivo activity is most likely attributed to poor colonization of the rhizosphere by the introduced Lysobacter strains. In conclusion, our results demonstrated that Lysobacter species have strong antagonistic activities against a range of pathogens, making them an important source for putative new enzymes and antimicrobial compounds. However, their potential role in R. solani disease suppressive soil could not be confirmed. In-depth omics'-based analyses will be needed to shed more light on the potential contribution of Lysobacter species to the collective activities of microbial consortia in disease suppressive soils.

No MeSH data available.


Related in: MedlinePlus

Sugar beet plant growth promotion by Lysobacter strains. (A) Sugar beet seeds were grown on 0.5 MS medium and plant growth promotion was determined when Lysobacter strains were inoculated on seeds or by volatiles. Each assay was performed with three to five replicates. F indicates fresh weight; D indicates dry weight. Light gray boxes indicate a statistical significant negative effect in plant growth when compared to the control and dark gray boxes indicate a statistical significant positive effect. Values within the boxes, indicates the % of increase/decrease of plant weight compared to the control. (B) Pictures of the plant growth promotion assays. C, control; La: L. antibioticus; Lc: L. capsici; Le: L. enzymogenes; Lg: L. gummosus. Significant differences (p < 0.05) with the uninoculated control were calculated using analysis of variance and Dunnet's post-hoc analysis.
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Figure 4: Sugar beet plant growth promotion by Lysobacter strains. (A) Sugar beet seeds were grown on 0.5 MS medium and plant growth promotion was determined when Lysobacter strains were inoculated on seeds or by volatiles. Each assay was performed with three to five replicates. F indicates fresh weight; D indicates dry weight. Light gray boxes indicate a statistical significant negative effect in plant growth when compared to the control and dark gray boxes indicate a statistical significant positive effect. Values within the boxes, indicates the % of increase/decrease of plant weight compared to the control. (B) Pictures of the plant growth promotion assays. C, control; La: L. antibioticus; Lc: L. capsici; Le: L. enzymogenes; Lg: L. gummosus. Significant differences (p < 0.05) with the uninoculated control were calculated using analysis of variance and Dunnet's post-hoc analysis.

Mentions: The ability of the Lysobacter strains to promote plant growth in vitro was tested for sugar beet, cauliflower, onion, and A. thaliana. For sugar beet, the 18 Lysobacter strains were applied to the seeds as well as to the root tips. For the first seed inoculation assay, almost all L. antibioticus strains negatively affected plant growth, decreasing plant biomass with 15–38% compared to the untreated control (Figure 4). One L. capsici and two L. enzymogenes strains negatively affected shoot biomass. In the second bioassay, no negative or positive effects on plant growth were observed for any of the strains (Figure 4), except for L. gummosus L26 which promoted root growth.


Diversity and Activity of Lysobacter Species from Disease Suppressive Soils.

Gómez Expósito R, Postma J, Raaijmakers JM, De Bruijn I - Front Microbiol (2015)

Sugar beet plant growth promotion by Lysobacter strains. (A) Sugar beet seeds were grown on 0.5 MS medium and plant growth promotion was determined when Lysobacter strains were inoculated on seeds or by volatiles. Each assay was performed with three to five replicates. F indicates fresh weight; D indicates dry weight. Light gray boxes indicate a statistical significant negative effect in plant growth when compared to the control and dark gray boxes indicate a statistical significant positive effect. Values within the boxes, indicates the % of increase/decrease of plant weight compared to the control. (B) Pictures of the plant growth promotion assays. C, control; La: L. antibioticus; Lc: L. capsici; Le: L. enzymogenes; Lg: L. gummosus. Significant differences (p < 0.05) with the uninoculated control were calculated using analysis of variance and Dunnet's post-hoc analysis.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4644931&req=5

Figure 4: Sugar beet plant growth promotion by Lysobacter strains. (A) Sugar beet seeds were grown on 0.5 MS medium and plant growth promotion was determined when Lysobacter strains were inoculated on seeds or by volatiles. Each assay was performed with three to five replicates. F indicates fresh weight; D indicates dry weight. Light gray boxes indicate a statistical significant negative effect in plant growth when compared to the control and dark gray boxes indicate a statistical significant positive effect. Values within the boxes, indicates the % of increase/decrease of plant weight compared to the control. (B) Pictures of the plant growth promotion assays. C, control; La: L. antibioticus; Lc: L. capsici; Le: L. enzymogenes; Lg: L. gummosus. Significant differences (p < 0.05) with the uninoculated control were calculated using analysis of variance and Dunnet's post-hoc analysis.
Mentions: The ability of the Lysobacter strains to promote plant growth in vitro was tested for sugar beet, cauliflower, onion, and A. thaliana. For sugar beet, the 18 Lysobacter strains were applied to the seeds as well as to the root tips. For the first seed inoculation assay, almost all L. antibioticus strains negatively affected plant growth, decreasing plant biomass with 15–38% compared to the untreated control (Figure 4). One L. capsici and two L. enzymogenes strains negatively affected shoot biomass. In the second bioassay, no negative or positive effects on plant growth were observed for any of the strains (Figure 4), except for L. gummosus L26 which promoted root growth.

Bottom Line: In conclusion, our results demonstrated that Lysobacter species have strong antagonistic activities against a range of pathogens, making them an important source for putative new enzymes and antimicrobial compounds.However, their potential role in R. solani disease suppressive soil could not be confirmed.In-depth omics'-based analyses will be needed to shed more light on the potential contribution of Lysobacter species to the collective activities of microbial consortia in disease suppressive soils.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW) Wageningen, Netherlands ; Laboratory of Phytopathology, Wageningen University and Research Centre Wageningen, Netherlands.

ABSTRACT
The genus Lysobacter includes several species that produce a range of extracellular enzymes and other metabolites with activity against bacteria, fungi, oomycetes, and nematodes. Lysobacter species were found to be more abundant in soil suppressive against the fungal root pathogen Rhizoctonia solani, but their actual role in disease suppression is still unclear. Here, the antifungal and plant growth-promoting activities of 18 Lysobacter strains, including 11 strains from Rhizoctonia-suppressive soils, were studied both in vitro and in vivo. Based on 16S rRNA sequencing, the Lysobacter strains from the Rhizoctonia-suppressive soil belonged to the four species Lysobacter antibioticus, Lysobacter capsici, Lysobacter enzymogenes, and Lysobacter gummosus. Most strains showed strong in vitro activity against R. solani and several other pathogens, including Pythium ultimum, Aspergillus niger, Fusarium oxysporum, and Xanthomonas campestris. When the Lysobacter strains were introduced into soil, however, no significant and consistent suppression of R. solani damping-off disease of sugar beet and cauliflower was observed. Subsequent bioassays further revealed that none of the Lysobacter strains was able to promote growth of sugar beet, cauliflower, onion, and Arabidopsis thaliana, either directly or via volatile compounds. The lack of in vivo activity is most likely attributed to poor colonization of the rhizosphere by the introduced Lysobacter strains. In conclusion, our results demonstrated that Lysobacter species have strong antagonistic activities against a range of pathogens, making them an important source for putative new enzymes and antimicrobial compounds. However, their potential role in R. solani disease suppressive soil could not be confirmed. In-depth omics'-based analyses will be needed to shed more light on the potential contribution of Lysobacter species to the collective activities of microbial consortia in disease suppressive soils.

No MeSH data available.


Related in: MedlinePlus