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New study shows soil bacteria can evolve more friendly to plants

Posted on 22 June 2021

Beneficial symbioses between eukaryotic and prokaryotic organisms have evolved multiple times during the history of life.

While such mutualistic interactions are commonly observed between plants and bacteria, direct evidence of the evolution of mutualism is yet scarce. 

The research team from the Utrecht University and University of York studied this by using experimental evolution approach, where bacterial evolution was tracked in real time in the plant roots. Their results show that initially plant antagonistic Pseudomonas protegens bacterium can rapidly evolve into a plant mutualist only within a few plant generations.

Dr Ville Friman from the Department of Biology says: “We found that bacteria can rapidly evolve in the roots Arabidopsis thaliana plant, leading to increase in the frequency of evolved mutants that are less antagonistic towards the plant. This evolutionary transition was driven by selection for less antagonistic but more competitive bacteria that could grow better on plant-derived nutrients and were more tolerant for plant-secreted antimicrobials”.

"One benefit of the experimental evolution approach is that researchers can create a ‘living’ fossil record of their evolving bacterial lineages and later identify potential mutations that could explain the evolutionary changes at the genetic level."

“The observed evolutionary changes were highly similar between independent replicate selection lines, which demonstrates that bacterial evolution can take highly predictable trajectories in plant roots. At the molecular level, evolutionary changes could be explained by key mutations in GacS/GacA two-component global regulator system, which is known to affect several bacterial traits, including regulation of phytotoxic secondary metabolites," continues Friman.

Together, findings show that a few mutations can comprehensively change how bacteria interact with plants, suggesting that plants could domesticate their microbiota by imposing positive selection for mutualistic bacterial genotypes.  

Read the research published in Nature Communications.