English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Background Nodule symbiosis with diazotrophic  Frankia  or rhizobium occurs in plant species belonging to ten taxonomic lineages within the related orders Fabales, Fagales, Cucurbitales, and Rosales. Phylogenomic studies indicate that this nitrogen-fixing nodulation trait has a single evolutionary origin. In legume model plants, the molecular interaction between plant and rhizobium microsymbiont is mapped to a significant degree. A specific LysM-type receptor kinase, LjEPR3 in  Lotus japonicus  and MtLYK10 in  Medicago truncatula , was found to act in a secondary identity-based mechanism, controlling intracellular rhizobium infection. Furthermore, LjEPR3 showed to bind surface exopolysaccharides of  Mesorhizobium loti , the diazotrophic microsymbiont of  L. japonicus .  EPR3  orthologous genes are not unique to legumes. Surprisingly, however, its ortholog  EXOPOLYSACCHARIDE RECEPTOR  ( EPR ) is pseudogenized in  Parasponia,  the only lineage of non-legume plants that nodulate also with rhizobium. Results Analysis of genome sequences showed that  EPR3  orthologous genes are highly conserved in nodulating plants. We identified a conserved retrotransposon insertion in the  EPR  promoter region in three  Parasponia  species, which associates with defected transcriptional regulation of this gene. Subsequently, we studied the  EPR  gene of two  Trema  species as they represent the sister genus of  Parasponia  for which it is assumed it lost the nitrogen-fixing nodulation trait. Both  Trema  species possess apparently functional  EPR  genes that have a nodulation-specific expression profile when introduced into a  Parasponia  background. This indicates the  EPR  gene functioned in nodulation in the  Parasponia-Trema  ancestor. Conclusion We conclude that nodule-specific expression of  EPR3  orthologous genes is shared between the legume and  Parasponia-Trema  lineage, suggesting an ancestral function in the nitrogen-fixing nodulation trait. Pseudogenization of  EPR  in  Parasponia  is an exceptional case in nodulating plants. We speculate that this may have been instrumental to the microsymbiont switch -from  Frankia  to rhizobium- that has occurred in the  Parasponia  lineage and the evolution of a novel crack entry infection mechanism.

Pseudogenization of the rhizobium-responsive EXOPOLYSACCHARIDE RECEPTOR in Parasponia is a rare event in nodulating plants