Genetic variation is associated with differences in facilitative and competitive interactions in the Rhizobium leguminosarum species complex.

Bryden Fields,J Peter W Young,Ellie Harrison,Ville‐Petri Friman,Stig U Andersen,Emma K Moffat

doi:10.1111/1462-2920.15720

Bryden Fields, J Peter W Young + Show 4 more

Open Access

https://doi.org/10.1111/1462-2920.15720

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Abstract

Competitive and facilitative interactions influence bacterial community composition, diversity and functioning. However, the role of genetic diversity for determining interactions between coexisting strains of the same, or closely related, species remains poorly understood. Here, we investigated the type (facilitative/inhibitory) and potential underlying mechanisms of pairwise interactions between 24 genetically diverse bacterial strains belonging to three genospecies (gsA,C,E) of the Rhizobium leguminosarum species complex. Interactions were determined indirectly, based on secreted compounds in cell-free supernatants, and directly, as growth inhibition in cocultures. We found supernatants mediated both facilitative and inhibitory interactions that varied greatly between strains and genospecies. Overall, gsE strains indirectly suppressed growth of gsA strains, while their own growth was facilitated by other genospecies' supernatants. Similar genospecies-level patterns were observed in direct competition, where gsA showed the highest susceptibility and gsE the highest inhibition capacity. At the genetic level, increased gsA susceptibility was associated with a non-random distribution of quorum sensing and secondary metabolite genes across genospecies. Together, our results suggest that genetic variation is associated with facilitative and competitive interactions, which could be important ecological mechanisms explaining R. leguminosarum diversity.

Highlights

Bacteria predominantly exist in complex, diverse communities where interacting species and genotypes coexist side by side despite competition for the same resources and niches (Stubbendieck and Straight, 2016; Gorter et al, 2020)
At the genetic level, increased gsA susceptibility was associated with a non-random distribution of quorum sensing and secondary metabolite genes across genospecies
Our results suggest that genetic variation is associated with facilitative and competitive interactions, which could be important ecological mechanisms explaining R. leguminosarum diversity

Summary

Introduction

Bacteria predominantly exist in complex, diverse communities where interacting species and genotypes coexist side by side despite competition for the same resources and niches (Stubbendieck and Straight, 2016; Gorter et al, 2020). Range from facilitative to competitive, affecting diversification, spatial distribution and abundance of different species and generating functional attributes at the community level that might be unobservable when only individual species are considered (Gorter et al, 2020). As a result, acknowledging both intra- and interspecies bacterial diversity is vital for understanding microbial community dynamics from assembly to functioning (Jousset et al, 2011; Lee et al, 2016; Stubbendieck and Straight, 2016; Gorter et al, 2020)

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