Disparate origins of Bradyrhizobium symbionts for invasive populations of Cytisus scoparius (Leguminosae) in North America. Issue 1 (28th April 2014)

• Record Type: Journal Article
• Authors: Horn, Kevin; Parker, Ingrid M.; Malek, Wanda; Rodríguez‐Echeverría, Susana; Parker, Matthew A.
• Is Part Of: FEMS microbiology ecology. Volume 89:Issue 1(2014)
• Page Start: 89
• Page End: 98
• Publication Date: 2014-04-28
• Subjects: Microbial ecology -- Periodicals; Microbiology -- Periodicals; 579.17
• DOI: 10.1111/1574-6941.12335
• Languages: English
• ISSNs: 0168-6496

Abstract

<abstract abstract-type="main" id="fem12335-abs-0001"> <title>Abstract</title> <p>To identify the geographic origin of nodule bacteria associated with invasion of the European legume <italic>Cytisus scoparius</italic> in the United States, isolates from 15 sites in six states were compared to > 200 <italic>Bradyrhizobium</italic> strains from indigenous legumes in the U.S., Mexico, Europe (six countries), Morocco, and Australia. Portions of five housekeeping loci (2849 bp) were sequenced, along with the <italic>nifD</italic> locus in the symbiosis island (SI) portion of the <italic>Bradyrhizobium</italic> chromosome. Bayesian phylogenetic analysis showed that North American <italic>C. scoparius</italic> symbionts had highly heterogeneous ancestry. Some were grouped into three distinct clades of European <italic>C. scoparius</italic> symbionts. One isolate had both housekeeping and SI genes belonging to a <italic>Bradyrhizobium</italic> clade from native legumes in western North America. Two other clades had mosaic ancestry: sequences for <italic>nifD</italic> as well as two other SI genes (<italic>nifH</italic>, <italic> nodC</italic>) were highly similar or identical to a <italic>C. scoparius</italic> strain from Spain, while their housekeeping loci belonged to American <italic>Bradyrhizobium</italic> clades. Thus, it appears that bacteria ancestrally associated with other North American legumes have evolved to utilize <italic>C. scoparius</italic>, by acquiring SI‐region genes from European <italic>C. scoparius</italic> symbionts. Inoculation assays indicated that North American isolates were as competent as European strains in promoting plant growth, consistent with the findings on symbiont ancestry.</p> </abstract>