Metabolism of Photosynthetic Bradyrhizobia during Root and Stem Symbiosis with<i>Aeschynomene</i>Legumes

Gourion, Benjamin; Bonaldi, Katia; Giraud, Éric

doi:10.1002/9781119053095.ch28

Cited by 1 publication

(6 citation statements)

References 36 publications

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“…The other version, PGC2, was highly syntenic among the remainder of the genomes from the B. japonicum supergroup and from the B. elkanii supergroup. Overall, these findings are thus consistent with those of previous studies on the genomes, respectively, of the nodulating strains (ORS278 and BTAi1) in the Photosynthetic supergroup and the non-nodulating B. cosmicum S23321 [20,23,30,31]. Also, as shown before [20], the major differences observed between the two PGCs involved inversions between BrBphP and ppR1 and lack of hem genes (excluding hemA) in PGC1, with the lack of bchEJ in PGC2 (see Fig.…”

Section: Discussionsupporting

confidence: 92%

“…For example, it was shown that the PGC1 system (found in the Bradyrhizobium Photosynthetic supergroup) is expressed under aerobic light conditions, while the system in Rhodopseudomonas palustris (i.e. encoded by a gene cluster with high similarity to PGC2 of Bradyrhizobium) is expressed under anaerobic light conditions [31,60]. In both systems the expression of the photosystem is mediated by the light-sensing ability of the bacteriophytochrome photoreceptor (BphP) and two transcriptional regulators PpsR1 and PpsR2.…”

Section: Discussionmentioning

confidence: 99%

“…In the Photosynthetic supergroup of Bradyrhizobium, photosynthesis is conferred by a photosynthesis gene cluster (PGC) of 45-50 kb in size [23,31]. The cluster encodes all the products needed for successful photosynthesis including bacteriochlorophyll biosynthesis (encoded by the bch genes), carotenoid biosynthesis (encoded by the crt genes), light-harvesting polypeptides (encoded by the pufLM genes) and the reaction centre subunits (encoded by the pufBA genes), as well as those involved in regulation (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…The cluster encodes all the products needed for successful photosynthesis including bacteriochlorophyll biosynthesis (encoded by the bch genes), carotenoid biosynthesis (encoded by the crt genes), light-harvesting polypeptides (encoded by the pufLM genes) and the reaction centre subunits (encoded by the pufBA genes), as well as those involved in regulation (e.g. bacteriophytochrome encoded by BrBphP and transcription factors encoded by ppsR1, ppsR2 and acsF) [26,31]. In terms of gene organization, this PGC generally resembles that of other photosynthetic Pseudomonadota (Proteobacteria), although regulation of the Bradyrhizobium PGC requires specific light conditions to initiate the process, controlled by the bacteriophytochrome photoreceptor (BrBphP).…”

Section: Introductionmentioning

confidence: 99%

“…Since then, it has also been identified in several other Bradyrhizobium symbionts of Aeschynomene (e.g. strains ORS278 and ORS375) [23,31,33]. Outside the Photosynthetic supergroup of Bradyrhizobium, the PGC has rarely been encountered and its discovery has largely been attributed to whole genome sequencing efforts [20].…”

Section: Introductionmentioning

confidence: 99%

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Complex evolutionary history of photosynthesis in Bradyrhizobium

Avontuur,

Wilken,

Palmer

et al. 2023

Microbial Genomics

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Bradyrhizobium comprises a diverse group of bacteria with various lifestyles. Although best known for their nodule-based nitrogen-fixation in symbiosis with legumes, a select group of bradyrhizobia are also capable of photosynthesis. This ability seems to be rare among rhizobia, and its origin and evolution in these bacteria remain a subject of substantial debate. Therefore, our aim here was to investigate the distribution and evolution of photosynthesis in Bradyrhizobium using comparative genomics and representative genomes from closely related taxa in the families Nitrobacteraceae, Methylobacteriaceae, Boseaceae and Paracoccaceae. We identified photosynthesis gene clusters (PGCs) in 25 genomes belonging to three different Bradyrhizobium lineages, notably the so-called Photosynthetic, B. japonicum and B. elkanii supergroups. Also, two different PGC architectures were observed. One of these, PGC1, was present in genomes from the Photosynthetic supergroup and in three genomes from a species in the B. japonicum supergroup. The second cluster, PGC2, was also present in some strains from the B. japonicum supergroup, as well as in those from the B. elkanii supergroup. PGC2 was largely syntenic to the cluster found in Rhodopseudomonas palustris and Tardiphaga . Bayesian ancestral state reconstruction unambiguously showed that the ancestor of Bradyrhizobium lacked a PGC and that it was acquired horizontally by various lineages. Maximum-likelihood phylogenetic analyses of individual photosynthesis genes also suggested multiple acquisitions through horizontal gene transfer, followed by vertical inheritance and gene losses within the different lineages. Overall, our findings add to the existing body of knowledge on Bradyrhizobium ’s evolution and provide a meaningful basis from which to explore how these PGCs and the photosynthesis itself impact the physiology and ecology of these bacteria.

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