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Homoserine catabolism by R hizobium leguminosarum bv. viciae 3841 requires a plasmid‐borne gene cluster that also affects competitiveness for nodulation
Author(s) -
Vanderlinde Elizabeth M.,
Hynes Michael F.,
Yost Christopher K.
Publication year - 2014
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.12196
Subject(s) - homoserine , rhizobium leguminosarum , biology , agrobacterium tumefaciens , gene cluster , plasmid , gene , mutant , microbiology and biotechnology , operon , rhizobiaceae , biochemistry , genetics , bacteria , symbiosis , quorum sensing , virulence , transgene
Summary Homoserine represents a substantial component of pea root exudate that may be important for plant–microbe interactions in the rhizosphere. We identified a gene cluster on plasmid pRL8JI that is required for homoserine utilization by R hizobium leguminosarum bv. viciae . The genes are arranged as two divergently expressed predicted operons that were induced by L ‐homoserine, pea root exudate, and were expressed on pea roots. A mutation in gene pRL80083 that prevented utilization of homoserine as a sole carbon and energy source affected the mutant's ability to nodulate peas and lentils competitively. The homoserine gene cluster was present in approximately 47% of natural R . leguminosarum isolates ( n = 59) and was strongly correlated with homoserine utilization. Conjugation of pRL8JI to R . leguminosarum 4292 or A grobacterium tumefaciens UBAPF 2 was sufficient for homoserine utilization. The presence of L ‐homoserine increased conjugation efficiency of pRL8JI from R . leguminosarum to a pRL8JI ‐cured derivative of R . leguminosarum 1062 and to A . tumefaciens UBAPF 2, and induced expression of the plasmid transfer gene trbB ; however, there was no difference in conjugation efficiency or trbB expression with A . tumefaciens UBAPF2pRL8 ‐ G m as the donor suggesting that other genes in R . leguminosarum may contribute to regulating conjugation of pRL8 in the presence of homoserine.