@article{fdi:010076551,
  title = {{F}rom intracellular bacteria to differentiated bacteroids : transcriptome and metabolome analysis in aeschynomene nodules using the {B}radyrhizobium sp. {S}train {ORS}285 bcl{A} mutant},
  author = {{L}amouche, {F}. and {C}haumeret, {A}. and {G}uefrachi, {I}. and {B}arriere, {Q}. and {P}ierre, {O}. and {G}uerard, {F}. and {G}ilard, {F}. and {G}iraud, {E}ric and {D}essaux, {Y}. and {G}akiere, {B}. and {T}imchenko, {T}. and {K}ereszt, {A}. and {M}ergaert, {P}. and {A}lunnia, {B}.},
  editor = {},
  language = {{ENG}},
  abstract = {{S}oil bacteria called rhizobia trigger the formation of root nodules on legume plants. {T}he rhizobia infect these symbiotic organs and adopt an intracellular lifestyle within the nodule cells, where they differentiate into nitrogen-fixing bacteroids. {S}everal legume lineages force their symbionts into an extreme cellular differentiation, comprising cell enlargement and genome endoreduplication. {T}he antimicrobial peptide transporter {B}cl{A} is a major determinant of this process in {B}radyrhizobium sp. strain {ORS}285, a symbiont of {A}eschynomene spp. {I}n the absence of {B}cl{A}, the bacteria proceed until the intracellular infection of nodule cells, but they cannot differentiate into enlarged polyploid and functional bacteroids. {T}hus, the bcl{A} nodule bacteria constitute an intermediate stage between the free-living soil bacteria and the nitrogen-fixing bacteroids. {M}etabolomics on whole nodules of {A}eschynomene afraspera and {A}eschynomene indica infected with the wild type or the bcl{A} mutant revealed 47 metabolites that differentially accumulated concomitantly with bacteroid differentiation. {B}acterial transcriptome analysis of these nodules demonstrated that the intracellular settling of the rhizobia in the symbiotic nodule cells is accompanied by a first transcriptome switch involving several hundred upregulated and downregulated genes and a second switch accompanying the bacteroid differentiation, involving fewer genes but ones that are expressed to extremely elevated levels. {T}he transcriptomes further suggested a dynamic role for oxygen and redox regulation of gene expression during nodule formation and a nonsymbiotic function of {B}cl{A}. {T}ogether, our data uncover the metabolic and gene expression changes that accompany the transition from intracellular bacteria into differentiated nitrogen-fixing bacteroids. {IMPORTANCE} {L}egume-rhizobium symbiosis is a major ecological process, fueling the biogeochemical nitrogen cycle with reduced nitrogen. {I}t also represents a promising strategy to reduce the use of chemical nitrogen fertilizers in agriculture, thereby improving its sustainability. {T}his interaction leads to the intracellular accommodation of rhizobia within plant cells of symbiotic organs, where they differentiate into nitrogen-fixing bacteroids. {I}n specific legume clades, this differentiation process requires the bacterial transporter {B}cl{A} to counteract antimicrobial peptides produced by the host. {T}ranscriptome analysis of {B}radyrhizobium wild-type and bcl{A} mutant bacteria in culture and in symbiosis with {A}eschynomene host plants dissected the bacterial transcriptional response in distinct phases and highlighted functions of the transporter in the free-living stage of the bacterial life cycle.},
  keywords = {{B}cl{A} {ABC} transporter ; legume-rhizobium symbiosis ; metabolome ; terminal ; bacteroid differentiation ; transcriptome},
  booktitle = {},
  journal = {{J}ournal of {B}acteriology},
  volume = {201},
  numero = {17},
  pages = {e00191 [19 p.]},
  ISSN = {0021-9193},
  year = {2019},
  DOI = {10.1128/jb.00191-19},
  URL = {https://www.documentation.ird.fr/hor/fdi:010076551},
}