Open AccessRelative involvement of nitrate and nitrite reduction in the competitiveness of Pseudomonas fluorescens in the rhizosphere of maize under non‐limiting nitrate conditions
Author(s) -
Ghiglione JeanFrançois,
Richaume Agnès,
Philippot Laurent,
Lensi Robert
Publication year - 2002
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.2002.tb00913.x
Subject(s) - rhizosphere , pseudomonas fluorescens , biology , nitrate , nitrite , denitrifying bacteria , denitrification , inoculation , population , pseudomonas , strain (injury) , pseudomonadales , horticulture , agronomy , botany , nitrogen , bacteria , ecology , chemistry , genetics , demography , organic chemistry , anatomy , sociology
Competition between different isogenic mutants of Pseudomonas fluorescens unable to carry out the first steps of the denitrification pathway was compared in soil micro‐columns non‐planted or planted with maize. A new isogenic mutant of P. fluorescens YT101 affected in both nitrate and nitrite respirations was constructed and used as a model of non‐denitrifying strain (FM69MS strain). The outcome of the selection exerted by the plant after co‐inoculation of FM69MS at the same ratio either with an isogenic denitrifier unable to reduce nitrate (Nar − mutant) or with an isogenic NO 2 − accumulator (Nir − mutant) was investigated in non‐limiting NO 3 − conditions. Regardless of the inoculated mixture, both strains were able to grow in both rhizosphere and non‐planted soil. The proportion of Nar − or Nir − strain in the Nar − +FM69MS or Nir − +FM69MS total introduced population remained stable in non‐planted soil. In the rhizosphere, we observed a higher competitiveness of the Nir − mutant compared with FM69MS, whereas the latter showed the same competitiveness as the Nar − mutant. These results provide the first demonstration that NO 3 − reduction is the main nitrogen‐dissimilating step controlling the competitiveness of P. fluorescens in the rhizosphere.