SUTN9-2 is a broad host range strain capable of symbiosis with several legumes. Two copies of T4SS clusters belonging to the tra/trb operon are observed on chromosomes with different gene arrangements.
Research Interests:
The interaction between leguminous plants and Bradyrhizobium is limited, known as host specificity. Therefore, the selection of an appropriate Bradyrhizobia for use as biofertilizer inoculum for legumes is necessary. The Arachis hypogea... more
The interaction between leguminous plants and Bradyrhizobium is limited, known as host specificity. Therefore, the selection of an appropriate Bradyrhizobia for use as biofertilizer inoculum for legumes is necessary. The Arachis hypogea L. is the most popular legume produced in the Lao People's Democratic Republic (PDR). Therefore, this research aimed to obtain the appropriate Bradyrhizobia that provides high efficiency in A. hypogea production in the Lao PDR. The 14 isolates were obtained from root nodules of A. hypogea L. trapped with Lao PDR soil samples. Three were the top isolates PMVTL-01, SMVTL-02, and BLXBL-03 showing high efficiency for peanut growth promotion. Strains PMVTL-01 and SMVTL-02 were closely related to the Bradyrhizobium geno sp. SA-3 Rp7b and B. zhanjiangense, respectively, whilst strain BLXBL-03 was closely related to Bradyrhizobium sp. CCBAU51745 and B. manausense BR3351. The competitiveness of these strains with Bradyrhizobium sp. SUTN9-2::GFP was analyz...
RpoN is an alternative sigma factor (sigma 54) that recruits the core RNA polymerase to promoters of genes. In bacteria, RpoN has diverse physiological functions. In rhizobia, RpoN plays a key role in the transcription of nitrogen... more
RpoN is an alternative sigma factor (sigma 54) that recruits the core RNA polymerase to promoters of genes. In bacteria, RpoN has diverse physiological functions. In rhizobia, RpoN plays a key role in the transcription of nitrogen fixation (nif) genes. The Bradyrhizobium sp. DOA9 strain contains a chromosomal (c) and plasmid (p) encoded RpoN protein. We used single and double rpoN mutants and reporter strains to investigate the role of the two RpoN proteins under free-living and symbiotic conditions. We observed that the inactivation of rpoNc or rpoNp severely impacts the physiology of the bacteria under free-living conditions, such as the bacterial motility, carbon and nitrogen utilization profiles, exopolysaccharide (EPS) production, and biofilm formation. However, free-living nitrogen fixation appears to be under the primary control of RpoNc. Interestingly, drastic effects of rpoNc and rpoNp mutations were also observed during symbiosis with Aeschynomene americana. Indeed, inocul...
Research Interests:
Research Interests:
Various technologies, such as light-emitting diodes (LEDs) and beneficial plant micro-organisms, have been applied to enhance plant growth and development. We aimed to develop appropriate technology by incorporating the benefits of LED... more
Various technologies, such as light-emitting diodes (LEDs) and beneficial plant micro-organisms, have been applied to enhance plant growth and development. We aimed to develop appropriate technology by incorporating the benefits of LED light, plant growth promoting rhizobacteria (PGPR), and arbuscular mycorrhiza fungi (AMF) into sweet girl cherry tomato (Solanum lycopersicum L.) seedling production. Our results demonstrated that incorporating red (R) and blue (B) LED lights, PGPR, and AMF positively affected tomato seedling growth. The optimal lighting conditions for tomato seedling growth were LEDs at 200 μmol/m2/s with a ratio of R60:B40 and 20 h/d exposure. The optimum LED-illuminated tomato seedlings significantly upregulated photosynthesis-related genes, including psbA, psbB, fdx, atpB, and rbcL. Plants inoculated with PGPR Bradyrhizobium sp. SUTN9-2, Bacillus velezensis SD10 and B. megaterium A20 had a high health index after inoculation. Furthermore, the optimized LED-illumin...
Research Interests:
<p>Double slash marks represent DNA regions that are not shown. Colored strips represent the conserved gene regions between the compared strains, and the color indicates the percentage similarity, as detailed in the key. T: region... more
<p>Double slash marks represent DNA regions that are not shown. Colored strips represent the conserved gene regions between the compared strains, and the color indicates the percentage similarity, as detailed in the key. T: region where the transposase genes were located.</p
Research Interests: Nitrogen Fixation, Genome Analysis, Similarity, GC, Iii, and 6 moreChromosome, Host Range, Plasmid, USDA, Doa, and MBP
<p>Each genome is represented by a circle, and the numbers of shared and unique genes are shown by the overlapping and nonoverlapping regions. The proportion of total genes represented by each area of the diagram is shown in... more
<p>Each genome is represented by a circle, and the numbers of shared and unique genes are shown by the overlapping and nonoverlapping regions. The proportion of total genes represented by each area of the diagram is shown in parentheses. The total number of genes in each genome is shown in square brackets.</p
Research Interests: Nitrogen Fixation, Genome Analysis, Similarity, GC, Iii, and 6 moreChromosome, Host Range, Plasmid, USDA, Doa, and MBP
<p>Bootstrap values are expressed as percentages of 1,000 replications. Evolutionary distances were computed using the Kimura two-parameter method. The bar represents one estimated substitution per 100-nucleotide positions. Strains... more
<p>Bootstrap values are expressed as percentages of 1,000 replications. Evolutionary distances were computed using the Kimura two-parameter method. The bar represents one estimated substitution per 100-nucleotide positions. Strains capable of Nod factor-dependent and -independent nodulation are marked with (ND) and (NI), respectively. Photosynthetic strains are highlighted in gray.</p
Research Interests: Nitrogen Fixation, Genome Analysis, Similarity, GC, Iii, and 6 moreChromosome, Host Range, Plasmid, USDA, Doa, and MBP
<p>DOA9 cells were digested in 1% pulse field grade (PFG) agarose plugs with proteinase K, as described in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0117392#sec002"... more
<p>DOA9 cells were digested in 1% pulse field grade (PFG) agarose plugs with proteinase K, as described in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0117392#sec002" target="_blank">Materials and Methods</a>, and run 0.8% certified megabase agarose in TAE buffer to separate fragments of 225–6,000 kb (A), or 1% certified megabase agarose in 0.5 x TBE buffer (B) to separate fragments of 225–2,200 kb, respectively. Closed arrowheads and open arrowheads indicate the putative chromosome and the plasmid, respectively. Lane M1: PFGE marker, 3.5–5.7 Mb, <i>Saccharomyces pombe</i> chromosomal DNA. Lane M2: low-range (2.03–194 kb) PFG marker DNA ladder. DOA9: DOA9 genomic DNA.</p
Research Interests: Nitrogen Fixation, Genome Analysis, Similarity, GC, Iii, and 6 moreChromosome, Host Range, Plasmid, USDA, Doa, and MBP
<p>Bootstrap values are expressed as percentages of 1,000 replications. Evolutionary distances were computed using the Kimura two-parameter method. The bar represents one estimated substitution per 100-nucleotide positions.</p
Research Interests: Nitrogen Fixation, Genome Analysis, Similarity, GC, Iii, and 6 moreChromosome, Host Range, Plasmid, USDA, Doa, and MBP
Nitrogen-fixing symbiosis is globally important in ecosystem functioning and agriculture, yet the evolutionary history of nodulation remains the focus of considerable debate. Recent evidence suggesting a single origin of nodulation... more
Nitrogen-fixing symbiosis is globally important in ecosystem functioning and agriculture, yet the evolutionary history of nodulation remains the focus of considerable debate. Recent evidence suggesting a single origin of nodulation followed by massive parallel evolutionary losses raises questions about why a few lineages in the N2-fixing clade retained nodulation and diversified as stable nodulators while most did not. Within legumes, nodulation is restricted to the two most diverse subfamilies, Papilionoideae and Caesalpinioideae, which show stable retention of nodulation across their core clades. We characterize two nodule anatomy types across 128 species in 56 of the 150 genera of the legume subfamily Caesalpinioideae: 1) fixation thread nodules (FTs), where nitrogen-fixing bacteroids are retained within the apoplast in modified infection threads and 2) symbiosomes, where rhizobia are symplastically internalized in the host cell cytoplasm within membrane-bound symbiosomes. Using ...
Research Interests:
Bradyrhizobium sp. DOA9 isolated from the legume Aeschynomene americana exhibited a broad host range and divergent nodulation (nod) genes compared with other members of the Bradyrhizobiaceae. Genome analysis of DOA9 revealed that its... more
Bradyrhizobium sp. DOA9 isolated from the legume Aeschynomene americana exhibited a broad host range and divergent nodulation (nod) genes compared with other members of the Bradyrhizobiaceae. Genome analysis of DOA9 revealed that its genome comprised a single chromosome of 7.1 Mbp and a plasmid of 0.7 Mbp. The chromosome showed highest similarity with that of the nod gene-harboring soybean symbiont B. japonicum USDA110, whereas the plasmid showed highest similarity with pBBta01 of the nod gene-lacking photo-synthetic strain BTAi1, which nodulates Aeschynomene species. Unlike in other bradyrhizo-bia, the plasmid of DOA9 encodes genes related to symbiotic functions including nodulation, nitrogen fixation, and type III/IV protein secretion systems. The plasmid has also a lower GC content (60.1%) than the chromosome (64.4%). These features suggest that the plasmid could be the origin of the symbiosis island that is found in the genome of other bradyrhizobia. The nod genes of DOA9 exhibi...
Research Interests:
Research Interests:
Bradyrhizobium sp. strain DOA9 contains two copies of the nifDK genes, nifDKc, located on the chromosome, and nifDKp, located on a symbiotic megaplasmid. Unlike most rhizobia, this bacterium displays nitrogenase activity under both... more
Bradyrhizobium sp. strain DOA9 contains two copies of the nifDK genes, nifDKc, located on the chromosome, and nifDKp, located on a symbiotic megaplasmid. Unlike most rhizobia, this bacterium displays nitrogenase activity under both free-living and symbiotic conditions. Transcriptional analysis using gusA reporter strains showed that both nifDK operons were highly expressed under symbiosis, whereas nifDKc was the most abundantly expressed under free-living conditions. During free-living growth, the nifDKp mutation did not affect nitrogenase activity, whereas nitrogenase activity was drastically reduced with the nifDKc mutant. This led us to suppose that nifDKc is the main contributor of nitrogenase activity in the free-living state. In contrast, during symbiosis, no effect of the nifDKc mutation was observed and the nitrogen-fixation efficiency of plants inoculated with the nifDKp mutant was reduced. This suggests that nifDKp plays the main role in nitrogenase enzyme activity during ...
Research Interests:
Research Interests: Symbiosis, Biology, Thailand, Medicine, Endocytosis, and 4 moreEndophytes, Fabaceae, Bradyrhizobium, and Endophyte
Research Interests:
Research Interests:
Research Interests:
Host-specific legume-rhizobium symbiosis is strictly controlled by rhizobial type III effectors (T3Es) in some cases. Here, we demonstrated that the symbiosis of Vigna radiata (mung bean) with Bradyrhizobium diazoefficiens USDA110 is... more
Host-specific legume-rhizobium symbiosis is strictly controlled by rhizobial type III effectors (T3Es) in some cases. Here, we demonstrated that the symbiosis of Vigna radiata (mung bean) with Bradyrhizobium diazoefficiens USDA110 is determined by NopE, and this symbiosis is highly dependent on host genotype. NopE specifically triggered incompatibility with V. radiata cv. KPS2, but it promoted nodulation in other varieties of V. radiata, including KPS1. Interestingly, NopE1 and its paralogue NopE2, which exhibits calcium-dependent autocleavage, yield similar results in modulating KPS1 nodulation. Furthermore, NopE is required for early infection and nodule organogenesis in compatible plants. Evolutionary analysis revealed that NopE is highly conserved among bradyrhizobia and plant-associated endophytic and pathogenic bacteria. Our findings suggest that V. radiata and B. diazoefficiens USDA110 may use NopE to optimize their symbiotic interactions by reducing phytohormone-mediated ETI...
Research Interests:
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Bradyrhizobium sp. DOA9 can nodulate a wide spectrum of legumes; however, unlike other bradyrhizobia, DOA9 carries a symbiotic plasmid harboring type III secretion system (T3SS) and several effector (T3E) genes, one of which encodes a new... more
Bradyrhizobium sp. DOA9 can nodulate a wide spectrum of legumes; however, unlike other bradyrhizobia, DOA9 carries a symbiotic plasmid harboring type III secretion system (T3SS) and several effector (T3E) genes, one of which encodes a new putative type III effector—SkP48. Here, we demonstrated the pivotal roles of SkP48 from Bradyrhizobium sp. DOA9 in inhibiting nodulation of various Vigna species and Crotalaria juncea and suppressing nodulation efficiency of Arachis hypogea. By contrast, the nodulation efficiency of a SkP48 mutant did not differ significantly with the DOA9 wild-type strain on Macroptilium atropurpureum and Stylosanthes hamata. An evolutionary analysis revealed that the SkP48 effector which contains a shikimate kinase and a SUMO protease (C48 cysteine peptidase) domain is distinct from the others effectors previously identified in others bradyrhizobia and pathogenic bacteria. Our findings suggest that the new putative T3E SkP48 is a key factor suppressing nodulation...
The Bradyrhizobium vignae strain ORS3257 is an elite strain recommended for cowpea inoculation in Senegal. This strain was recently shown to establish symbioses on some Aeschynomene species using a cocktail of Type III effectors (T3Es)... more
The Bradyrhizobium vignae strain ORS3257 is an elite strain recommended for cowpea inoculation in Senegal. This strain was recently shown to establish symbioses on some Aeschynomene species using a cocktail of Type III effectors (T3Es) secreted by the T3SS machinery. In this study, using a collection of mutants in different T3Es genes, we sought to identify the effectors that modulate the symbiotic properties of ORS3257 in three Vigna species (V. unguiculata, V. radiata and V. mungo). While the T3SS had a positive impact on the symbiotic efficiency of the strain in V. unguiculata and V. mungo, it blocked symbiosis with V. radiata. The combination of effectors promoting nodulation in V. unguiculata and V. mungo differed, in both cases, NopT and NopAB were involved, suggesting they are key determinants for nodulation, and to a lesser extent, NopM1 and NopP1, which are additionally required for optimal symbiosis with V. mungo. In contrast, only one effector, NopP2, was identified as th...