Competence for transcellular infection in the root cortex involves a post-replicative, cell-cycle exit decision in Medicago truncatula
During root nodule symbiosis (RNS), cell-division activity is reinitiated and sustained in the root cortex to create a hospitable cellular niche. Such a temporary and spatially confined site is required to render host cells compatible with the intracellular progression of rhizobia. Although it has b...
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| Main Authors: | , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
eLife Sciences Publications Ltd
2025-07-01
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| Series: | eLife |
| Subjects: | |
| Online Access: | https://elifesciences.org/articles/88588 |
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| Summary: | During root nodule symbiosis (RNS), cell-division activity is reinitiated and sustained in the root cortex to create a hospitable cellular niche. Such a temporary and spatially confined site is required to render host cells compatible with the intracellular progression of rhizobia. Although it has been suggested that early infection events might involve a pre-mitotic cell-cycle arrest, this process has not been dissected with cellular resolution. Here, we show that a dual-color Medicago histone reporter robustly identifies cells with different mitotic or endoreduplication activities in the root cortex. By imaging deep root tissues, we found that a confined trajectory of cortical cells that are transcellularly passed by infection threads is in a stage of the cell cycle that is distinct from directly adjacent cells. Distinctive features of infected cells include nuclear widening and large-scale chromatin rearrangements consistent with a cell-cycle exit prior to differentiation. Using a combination of fluorescent reporters demarcating cell-cycle phase progression, we confirmed that a reduced proliferation potential and modulating the G2/M transition, a process possibly controlled by the NF-YA1 transcription factor, mark the success of rhizobial delivery to nodule cells. |
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| ISSN: | 2050-084X |