Taking ecological function seriously: soil microbial communities can obviate allelopathic effects of released metabolites.
BACKGROUND
Allelopathy (negative, plant-plant chemical interactions) has been largely studied as an autecological process, often assuming simplistic associations between pairs of isolated species. The growth inhibition of a species in filter paper bioassay enriched with a single chemical is commonly interpreted as evidence of an allelopathic interaction, but for some of these putative examples of allelopathy, the results have not been verifiable in more natural settings with plants growing in soil.


RESULTS
On the basis of filter paper bioassay, a recent study established allelopathic effects of m-tyrosine, a component of root exudates of Festuca rubra ssp. commutata. We re-examined the allelopathic effects of m-tyrosine to understand its dynamics in soil environment. Allelopathic potential of m-tyrosine with filter paper and soil (non-sterile or sterile) bioassays was studied using Lactuca sativa, Phalaris minor and Bambusa arundinacea as assay species. Experimental application of m-tyrosine to non-sterile and sterile soil revealed the impact of soil microbial communities in determining the soil concentration of m-tyrosine and growth responses.


CONCLUSIONS
Here, we show that the allelopathic effects of m-tyrosine, which could be seen in sterilized soil with particular plant species were significantly diminished when non-sterile soil was used, which points to an important role for rhizosphere-specific and bulk soil microbial activity in determining the outcome of this allelopathic interaction. Our data show that the amounts of m-tyrosine required for root growth inhibition were higher than what would normally be found in F. rubra ssp. commutata rhizosphere. We hope that our study will motivate researchers to integrate the role of soil microbial communities in bioassays in allelopathic research so that its importance in plant-plant competitive interactions can be thoroughly evaluated.
Kaur
Harleen
H
Max-Planck-Institute for Chemical Ecology, Department of Molecular Ecology, Jena, Germany.
Kaur
Rajwant
R
Kaur
Surinder
S
Baldwin
Ian T
IT
Inderjit
D031723:Bambusa / Q000187:drug effects / Q000254:growth & development; D001673:Biodegradation, Environmental; D004463:Ecology; D031751:Festuca / Q000502:physiology*; D018545:Lactuca / Q000187:drug effects / Q000254:growth & development; D031783:Phalaris / Q000187:drug effects / Q000254:growth & development; D018517:Plant Roots / Q000254:growth & development / Q000502:physiology; D012988:Soil Microbiology; D013045:Species Specificity; D014443:Tyrosine / Q000032:analysis / Q000378:metabolism* / Q000633:toxicity
D014443:Tyrosine; C015566:3-tyrosine