Involvement of the Azorhizobial Chromosome Partition Gene (parA) in the Onset of Bacteroid Differentiation during Sesbania rostrata Stem Nodule Development
Resource
APPLIED AND ENVIRONMENTAL MICROBIOLOGY, 77(13), 4371-4382
Journal
Applied and Environmental Microbiology
Journal Volume
77
Journal Issue
13
Pages
4371-4382
Date Issued
2011
Date
2011
Author(s)
Lee, Kyung-Bum
Wang, Yu-Sheng
Peng, Min-Hua
Suzuki, Shino
Suzuki, Tadahiro
Oyaizu, Hiroshi
Abstract
A parA gene in-frame deletion mutant of Azorhizobium caulinodans ORS571 (ORS571-ΔparA) was constructed to evaluate the roles of the chromosome-partitioning gene on various bacterial traits and on the development of stem-positioned nodules. The ΔparA mutant showed a pleiomorphic cell shape phenotype and was polyploid, with differences in nucleoid sizes due to dramatic defects in chromosome partitioning. Upon inoculation of the ΔparA mutant onto the stem of Sesbania rostrata, three types of immature nodule-like structures with impaired nitrogen-fixing activity were generated. Most showed signs of bacteroid early senescence. Moreover, the ΔparA cells within the nodule-like structures exhibited multiple developmental-stage phenotypes. Since the bacA gene has been considered an indicator for bacteroid formation, we applied the expression pattern of bacA as a nodule maturity index in this study. Our data indicate that the bacA gene expression is parA dependent in symbiosis. The presence of the parA gene transcript was inversely correlated with the maturity of nodule; the transcript was switched off in fully mature bacteroids. In summary, our experimental evidence demonstrates that the parA gene not only plays crucial roles in cellular development when the microbe is free-living but also negatively regulates bacteroid formation in S. rostrata stem nodules. © 2011, American Society for Microbiology.
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Other Subjects
Azorhizobium caulinodans; Cell shapes; Cellular development; Deletion mutants; Experimental evidence; Expression patterns; Gene transcripts; Maturity indices; Nucleoids; Sesbania rostrata; Chromosomes; Nitrogen fixation; Gene expression; bacterial protein; carrier protein; chromosome partition proteins, bacterial; bacterium; chromosome; gene expression; legume; nitrogen fixation; nodulation; phenotype; stem; article; Azorhizobium caulinodans; gene deletion; genetics; growth, development and aging; metabolism; microbiology; nitrogen fixation; physiology; plant stem; Sesbania; symbiosis; Azorhizobium caulinodans; Bacterial Proteins; Gene Deletion; Membrane Transport Proteins; Nitrogen Fixation; Plant Stems; Sesbania; Symbiosis; Azorhizobium caulinodans; Bacteria (microorganisms); Sesbania rostrata
Type
journal article
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