Trifolium species associate with a similar richness of soil-borne mutualists in their introduced and native ranges

Aim: While plant species introduced to new regions may benefit from escaping natural enemies, their success may be impaired by losing key mutualists. We aimed to elucidate whether a selection of annual and perennial Trifolium (clover) species have lost associations with nitrogen-fixing bacteria (rhizobia) and arbuscular mycorrhizal fungi (AMF) in their introduced range. Location: Introduced range in New Zealand (NZ) and native range in the United Kingdom (UK). Methods: We compared the strain richness of rhizobia associated with five Trifolium species in both ranges using genetic fingerprinting (rep-PCR with ERIC primers). Phylogenetic analysis of the nodD gene was conducted to test for between-range differences in rhizobia genotypes associated with seven Trifolium species. We also used TRFLP to compare the richness of AMF associated with three Trifolium species in both ranges. Results: Genetic fingerprinting indicated that Trifolium associate with a similar richness of rhizobia strains in NZ as they do in the UK. According to variation in the nodD gene, genotypes of rhizobia were indistinguishable between NZ and UK provenances. A total of 17 AMF operational taxonomic units were detected but there were no significant between-range differences in richness or in community structure. Main conclusions: Contrary to general expectations regarding the loss of mutualists following species introduction, our findings suggest that alien plants, including those accidentally introduced, can have access to rich communities of soil-borne mutualists that are likely to facilitate successful naturalization.