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The purB gene controls rhizosphere colonization by Pantoea agglomerans
Author(s) -
Chauhan P.S.,
Nautiyal C.S.
Publication year - 2010
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/j.1472-765x.2009.02779.x
Subject(s) - pantoea agglomerans , rhizosphere , colonization , biology , library science , geography , microbiology and biotechnology , bacteria , genetics , computer science
Abstract Aims: To isolate the rhizosphere competence‐defective transposon Tn 5 mutant of Pantoea agglomerans NBRISRM (SRM) and to identify the gene causing defect in its root colonization ability. Methods and Results: From over 5000 clones containing Tn 5 , one mutant P. agglomerans NBRISRMT (SRMT) showing 6 log units less colonization when compared with SRM, after 30 days in sand‐nonsterilized soil assay system was selected for further work to determine the effects of the mutation on rhizosphere competence. Southern hybridization analysis of restricted genomic DNA of SRMT demonstrated that the mutant had a single Tn 5 insert. SRM increased in titre to about 2 × 10 8 CFU g −1 root, compared with the indigenous bacterial population of heterotrophs of about 5 × 10 7 CFU g −1 root. In contrast, 30 days later, the titre value of SRMT was almost undetectable at 1 × 10 2 CFU g −1 root, demonstrating its inability to survive and colonize the rhizosphere. Sequencing of the flanking region of the Tn 5 mutant revealed that Tn 5 disrupted the purB gene. Conclusions: A defect in the colonization phenotype of the SRMT was attributed to the disruption in adenylosuccinate lyase (EC 4.3.2.2) which is encoded by the pur B gene and is required for rhizosphere colonization in P. agglomerans . Significantly less exopolysaccharide and biofilm was formed by SRMT when compared to SRM, because of the disruption of the purB gene. Significance and Impact of the Study: This work provides the first evidence for a functional role of purB gene in rhizosphere competence and root colonization by any rhizobacteria.