scholarly journals Overexpression of the Chromosome Partitioning Gene parA in Azorhizobium caulinodans ORS571 Alters the Bacteroid Morphotype in Sesbania rostrata Stem Nodules

2019 ◽  
Vol 10 ◽  
Author(s):  
Hsiao-Lin Chien ◽  
Wan-Zhen Huang ◽  
Ming-Yen Tsai ◽  
Chiung-Hsiang Cheng ◽  
Chi-Te Liu
Keyword(s):  
Sesbania Rostrata ◽  
Azorhizobium Caulinodans ◽  
Chromosome Partitioning ◽  
Azorhizobium Caulinodans Ors571

scholarly journals Glutaredoxins Play an Important Role in the Redox Homeostasis and Symbiotic Capacity of Azorhizobium caulinodans ORS571

2020 ◽  
Vol 33 (12) ◽  
pp. 1381-1393
Author(s):  
Yajun Cao ◽  
Gaofei Jiang ◽  
Mingxu Li ◽  
Xingxing Fang ◽  
Dan Zhu ◽  
...  
Keyword(s):  
Redox State ◽  
Bacterial Resistance ◽  
Redox Homeostasis ◽  
Sesbania Rostrata ◽  
Limited Information ◽  
Azorhizobium Caulinodans ◽  
Cellular Redox ◽  
Symbiotic Associations ◽  
Functional Analyses ◽  
Azorhizobium Caulinodans Ors571

Glutaredoxin (GRX) plays an essential role in the control of the cellular redox state and related pathways in many organisms. There is limited information on GRXs from the model nitrogen (N2)-fixing bacterium Azorhizobium caulinodans. In the present work, we identified and performed functional analyses of monothiol and dithiol GRXs in A. caulinodans in the free-living state and during symbiosis with Sesbania rostrata. Our data show that monothiol GRXs may be very important for bacterial growth under normal conditions and in response to oxidative stress due to imbalance of the redox state in grx mutants of A. caulinodans. Functional redundancies were also observed within monothiol and dithiol GRXs in terms of different physiological functions. The changes in catalase activity and iron content in grx mutants were assumed to favor the maintenance of bacterial resistance against oxidants, nodulation, and N2 fixation efficiency in this bacterium. Furthermore, the monothiol GRX12 and dithiol GRX34 play a collective role in symbiotic associations between A. caulinodans and Sesbania rostrata. Our study provided systematic evidence that further investigations are required to understand the importance of glutaredoxins in A. caulinodans and other rhizobia.

scholarly journals Rhizobial Factors Required for Stem Nodule Maturation and Maintenance in Sesbania rostrata-Azorhizobium caulinodans ORS571 Symbiosis

2007 ◽  
Vol 73 (20) ◽  
pp. 6650-6659 ◽  
Author(s):  
Shino Suzuki ◽  
Toshihiro Aono ◽  
Kyung-Bum Lee ◽  
Tadahiro Suzuki ◽  
Chi-Te Liu ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Sesbania Rostrata ◽  
Azorhizobium Caulinodans ◽  
Physiological Mechanisms ◽  
Repeated Observations ◽  
Stem Nodule ◽  
Tropical Legume ◽  
Fixation Activity ◽  
Stem Nodulation ◽  
Azorhizobium Caulinodans Ors571

ABSTRACT The molecular and physiological mechanisms behind the maturation and maintenance of N2-fixing nodules during development of symbiosis between rhizobia and legumes still remain unclear, although the early events of symbiosis are relatively well understood. Azorhizobium caulinodans ORS571 is a microsymbiont of the tropical legume Sesbania rostrata, forming N2-fixing nodules not only on the roots but also on the stems. In this study, 10,080 transposon-inserted mutants of A. caulinodans ORS571 were individually inoculated onto the stems of S. rostrata, and those mutants that induced ineffective stem nodules, as displayed by halted development at various stages, were selected. From repeated observations on stem nodulation, 108 Tn5 mutants were selected and categorized into seven nodulation types based on size and N2 fixation activity. Tn5 insertions of some mutants were found in the well-known nodulation, nitrogen fixation, and symbiosis-related genes, such as nod, nif, and fix, respectively, lipopolysaccharide synthesis-related genes, C4 metabolism-related genes, and so on. However, other genes have not been reported to have roles in legume-rhizobium symbiosis. The list of newly identified symbiosis-related genes will present clues to aid in understanding the maturation and maintenance mechanisms of nodules.

scholarly journals A Dual Role of Amino Acids from Sesbania rostrata Seed Exudates in the Chemotaxis Response of Azorhizobium caulinodans ORS571

2019 ◽  
Vol 32 (9) ◽  
pp. 1134-1147 ◽  
Author(s):  
Xiaolin Liu ◽  
Zhihong Xie ◽  
Yixuan Wang ◽  
Yu Sun ◽  
Xiaoxiao Dang ◽  
...  
Keyword(s):  
Amino Acids ◽  
Dual Role ◽  
Chemotactic Response ◽  
Nodule Formation ◽  
Sesbania Rostrata ◽  
Azorhizobium Caulinodans ◽  
Regulation Of Expression ◽  
Chemotaxis Proteins ◽  
Azorhizobium Caulinodans Ors571

Azorhizobium caulinodans ORS571 can induce nodule formation on the roots and the stems of its host legume, Sesbania rostrata. Plant exudates are essential in the dialogue between microbes and their host plant and, in particular, amino acids can play an important role in the chemotactic response of bacteria. Histidine, arginine, and aspartate, which are the three most abundant amino acids present in S. rostrata seed exudates, behave as chemoattractants toward A. caulinodans. A position-specific-iterated BLAST analysis of the methyl-accepting chemotaxis proteins (MCPs) (chemoreceptors) in the genome of A. caulinodans was performed. Among the 43 MCP homologs, two MCPs harboring a dCache domain were selected as possible cognate amino acid MCPs. After analysis of relative gene expression levels and construction of a gene-deleted mutant strain, one of them, AZC_0821 designed as TlpH, was confirmed to be responsible for the chemotactic response to the three amino acids. In addition, it was found that these three amino acids can also influence chemotaxis of A. caulinodans independently of the chemosensory receptors, by being involved in the increase of the expression level of several che and fla genes involved in the chemotaxis pathway and flagella synthesis. Thus, the contribution of amino acids present in seed exudates is directly related to the role as chemoattractants and indirectly related to the role in the regulation of expression of key genes involved in chemotaxis and motility. This “dual role” is likely to influence the formation of biofilms by A. caulinodans and the host root colonization properties of this bacterium.

Root nodulation of Sesbania rostrata suppresses stem nodulation by Sinorhizobium teranga but not Azorhizobium caulinodans

1996 ◽  
Vol 42 (2) ◽  
pp. 187-190 ◽  
Author(s):  
Kodjo Tomekpe ◽  
Marcelle Holsters ◽  
Bernard Dreyfus
Keyword(s):  
Host Plant ◽  
Root Nodules ◽  
Sesbania Rostrata ◽  
Efficient Production ◽  
Nod Factors ◽  
Azorhizobium Caulinodans ◽  
Experimental Conditions ◽  
Nod Factor ◽  
Stem Nodulation ◽  
Azorhizobium Caulinodans Ors571

Azorhizobium caulinodans ORS571 and Sinorhizobium teranga ORS51 and ORS52 are symbionts of the same host plant Sesbania rostrata. In nature, A. caulinodans nodulates more competitively the stem-located infection sites of Sesbania rostrata. Sinorhizobium strains, although frequently present in root nodules, are seldom found in stem nodules. One probable explanation for this phenomenon is the more abundant presence of Azorhizobium on the leaf and stem surfaces of the host plant. Work presented here hints at other plausible factors that determine the greater "stem specificity" of Azorhizobium. We found that under experimental conditions in which roots are not inoculated, all strains nodulated stems very well. However, ORS51 and ORS52 were much more sensitive than ORS571 to suppression of stem nodulation by previous root inoculation. The introduction of the regulatory nodD gene from A. caulinodans diminished the sensitivity to this suppression, probably by enhanced nod gene expression and subsequent Nod factor production. Our hypothesis is that the greater infectivity of ORS571 is due to a more efficient production of mitogenic Nod factors at stem-located infection sites, thereby more readily overcoming systemic suppression caused by previous root inoculations.Key words: autoregulation, nitrogen fixation, rhizobial ecology, systemic suppression of nodulation.

scholarly journals Involvement of the Azorhizobial Chromosome Partition Gene (parA) in the Onset of Bacteroid Differentiation during Sesbania rostrata Stem Nodule Development

2011 ◽  
Vol 77 (13) ◽  
pp. 4371-4382 ◽  
Author(s):  
Chi-Te Liu ◽  
Kyung-Bum Lee ◽  
Yu-Sheng Wang ◽  
Min-Hua Peng ◽  
Kung-Ta Lee ◽  
...  
Keyword(s):  
Cell Shape ◽  
Deletion Mutant ◽  
Nodule Development ◽  
Sesbania Rostrata ◽  
Gene Transcript ◽  
Azorhizobium Caulinodans ◽  
Free Living ◽  
Content Type ◽  
Chromosome Partitioning ◽  
Cellular Development

ABSTRACTAparAgene in-frame deletion mutant ofAzorhizobium caulinodansORS571 (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 ΔparAmutant 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 ΔparAmutant onto the stem ofSesbania rostrata, three types of immature nodule-like structures with impaired nitrogen-fixing activity were generated. Most showed signs of bacteroid early senescence. Moreover, the ΔparAcells within the nodule-like structures exhibited multiple developmental-stage phenotypes. Since thebacAgene has been considered an indicator for bacteroid formation, we applied the expression pattern ofbacAas a nodule maturity index in this study. Our data indicate that thebacAgene expression isparAdependent in symbiosis. The presence of theparAgene 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 theparAgene not only plays crucial roles in cellular development when the microbe is free-living but also negatively regulates bacteroid formation inS. rostratastem nodules.

scholarly journals Functional Exploration of the Bacterial Type VI Secretion System in Mutualism: Azorhizobium caulinodans ORS571–Sesbania rostrata as a Research Model

2018 ◽  
Vol 31 (8) ◽  
pp. 856-867 ◽  
Author(s):  
Hsiao-Han Lin ◽  
Hsin-Mei Huang ◽  
Manda Yu ◽  
Erh-Min Lai ◽  
Hsiao-Lin Chien ◽  
...  
Keyword(s):  
Culture Conditions ◽  
Secretion System ◽  
Sesbania Rostrata ◽  
Research Model ◽  
Azorhizobium Caulinodans ◽  
Wild Type ◽  
Type Vi Secretion System ◽  
Type Vi Secretion ◽  
Azorhizobium Caulinodans Ors571 ◽  
Bacterial Type

The bacterial type VI secretion system (T6SS) has been considered the armed force of bacteria because it can deliver toxin effectors to prokaryotic or eukaryotic cells for survival and fitness. Although many legume symbiotic rhizobacteria encode T6SS in their genome, the biological function of T6SS in these bacteria is still unclear. To elucidate this issue, we used Azorhizobium caulinodans ORS571 and its symbiotic host Sesbania rostrata as our research model. By using T6SS gene deletion mutants, we found that T6SS provides A. caulinodans with better symbiotic competitiveness when coinfected with a T6SS-lacking strain, as demonstrated by two independent T6SS-deficient mutants. Meanwhile, the symbiotic effectiveness was not affected by T6SS because the nodule phenotype, nodule size, and nodule nitrogen-fixation ability did not differ between the T6SS mutants and the wild type when infected alone. Our data also suggest that under several lab culture conditions tested, A. caulinodans showed no T6SS-dependent interbacterial competition activity. Therefore, instead of being an antihost or antibacterial weapon of the bacterium, the T6SS in A. caulinodans ORS571 seems to participate specifically in symbiosis by increasing its symbiotic competitiveness.

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