Abstract
Lotus species develop infection threads to guide rhizobia into nodule cells. However, there is evidence that some species have a genetic repertoire to allow other modes of infection. By conducting confocal and electron microscopy, quantification of marker gene expression, and phenotypic analysis of transgenic roots infected with mutant rhizobia, we elucidated the infection mechanism used by Rhizobium leguminosarum Norway to colonize Lotus burttii. Rhizobium leguminosarum Norway induces a distinct host transcriptional response compared with Mesorhizobium loti. It infects L. burttii utilizing an epidermal and transcellular infection thread-independent mechanism at high frequency. The entry into plant cells occurs directly from the apoplast and is primarily mediated by 'peg'-like structures, the formation of which is dependent on the production of Nod factor by the rhizobia. These results demonstrate that Lotus species can exhibit duality in their infection mechanisms depending on the rhizobial strain that they encounter. This is especially relevant in the context of interactions in the rhizosphere where legumes do not encounter single strains, but complex rhizobial communities. Additionally, our findings support a perception mechanism at the nodule cell entry interface, reinforcing the idea that there are successive checkpoints during rhizobial infection.
Highlights
Legumes engage in a mutualistic interaction with a group of diazotrophic bacteria collectively known as rhizobia
By conducting confocal and electron microscopy, quantification of marker gene expression, and phenotypic analysis of transgenic roots infected with mutant rhizobia, we elucidated the infection mechanism used by Rhizobium leguminosarum Norway to colonize Lotus burttii
Agrobacterium strains used in the hairy root transformation experiment were grown for 1 d at 28 °C in yeast extract broth (YEB) (Vervliet et al, 1975).The Escherichia coli strains used in the conjugation assay were grown for 1 d at 37 °C in Luria Bertani (LB) broth
Summary
Legumes engage in a mutualistic interaction with a group of diazotrophic bacteria collectively known as rhizobia In this interaction, the host plant provides photosynthetic products in exchange for ammonia converted from atmospheric nitrogen by the rhizobia (Oldroyd et al, 2011). The infection programme ensures that the rhizobia are guided from the root surface into cells of a dividing nodule primordium in three conceptual steps: (i) crossing of the epidermis; (ii) cortical spreading; and (iii) uptake of rhizobia into plant cells. This is attained differently depending on the host legume (Ibáñez et al, 2017).
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
