Open AccessAnalysis of the role of the two flagella of Bradyrhizobium japonicum in competition for nodulation of soybean
Author(s) -
Althabegoiti Maria Julia,
Covelli Julieta M.,
PérezGiménez Julieta,
Quelas Juan Ignacio,
Mongiardini Elías J.,
López Maria Florencia,
LópezGarcía Silvina L.,
Lodeiro Aníbal R.
Publication year - 2011
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2011.02280.x
Subject(s) - flagellin , bradyrhizobium japonicum , mutant , flagellum , strain (injury) , competition (biology) , biology , motility , microbiology and biotechnology , vermiculite , bradyrhizobium , inoculation , botany , symbiosis , rhizobiaceae , biochemistry , horticulture , gene , bacteria , genetics , rhizobium , anatomy , ecology
Bradyrhizobium japonicum has two types of flagella. One has thin filaments consisting of the 33‐kDa flagellins FliCI and FliCII (FliCI‐II) and the other has thick filaments consisting of the 65‐kDa flagellins FliC1, FliC2, FliC3, and FliC4 (FliC1‐4). To investigate the roles of each flagellum in competition for nodulation, we obtained mutants deleted in fliCI‐II and/or fliC1‐4 in the genomic backgrounds of two derivatives from the reference strain USDA 110: the streptomycin‐resistant derivative LP 3004 and its more motile derivative LP 3008. All mutations diminished swimming motility. When each mutant was co‐inoculated with the parental strain on soybean plants cultivated in vermiculite either at field capacity or flooded, their competitiveness differed according to the flagellin altered. Δ fliCI‐II mutants were more competitive, occupying 64–80% of the nodules, while Δ fliC1‐4 mutants occupied 45–49% of the nodules. Occupation by the nonmotile double mutant decreased from 55% to 11% as the water content of the vermiculite increased from 85% to 95% field capacity to flooding. These results indicate that the influence of motility on competitiveness depended on the water status of the rooting substrate.