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Overexpression of hns in the plant growth‐promoting bacterium Enterobacter cloacae UW5 increases root colonization
Author(s) -
English M.M.,
Coulson T.J.D.,
Horsman S.R.,
Patten C.L.
Publication year - 2010
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/j.1365-2672.2009.04620.x
Subject(s) - enterobacter cloacae , colonization , biology , mutant , transposable element , transposon mutagenesis , seedling , microbiology and biotechnology , gene , inoculation , botany , escherichia coli , enterobacteriaceae , genetics , horticulture
Aims: Plant growth‐promoting rhizobacteria (PGPR) introduced into soil often do not compete effectively with indigenous micro‐organisms for plant colonization. The aim of this study was to identify novel genes that are important for root colonization by the PGPR Enterobacter cloacae UW5. Methods and Results: A library of transposon mutants of Ent. cloacae UW5 was screened for mutants with altered ability to colonize canola roots using a thermal asymmetric interlaced (TAIL)‐PCR‐based approach. A PCR fragment from one mutant was reproducibly amplified at greater levels from genomic DNA extracted from mutant pools recovered from seedling roots 6 days after seed inoculation compared to that from the cognate inoculum cultures. Competition assays confirmed that the purified mutant designated Ent. cloacae J28 outcompetes the wild‐type strain on roots but not in liquid cultures. In Ent. cloacae J28, the transposon is inserted upstream of the hns gene. Quantitative RT‐PCR showed that transposon insertion increased expression of hns on roots. Conclusions: These results indicate that increased expression of hns in Ent. cloacae enhances competitive colonization of roots. Significance and Impact of the Study: A better understanding of the genes involved in plant colonization will contribute to the development of PGPR that can compete more effectively in agricultural soils.