1. Conserved cis-elements enable NODULES WITH ACTIVATED DEFENSE1 regulation by NODULE INCEPTION during nodulation.
- Author
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Yu H, Xiao A, Zou Z, Wu Q, Chen L, Zhang D, Sun Y, Wang C, Cao J, Zhu H, Zhang Z, and Cao Y
- Subjects
- Nitrogen Fixation genetics, Medicago truncatula genetics, Medicago truncatula microbiology, Medicago truncatula metabolism, Promoter Regions, Genetic genetics, Mutation genetics, Transcription Factors genetics, Transcription Factors metabolism, Conserved Sequence, Plant Proteins genetics, Plant Proteins metabolism, Lotus genetics, Lotus microbiology, Lotus metabolism, Root Nodules, Plant genetics, Root Nodules, Plant metabolism, Root Nodules, Plant microbiology, Gene Expression Regulation, Plant, Plant Root Nodulation genetics, Symbiosis genetics
- Abstract
Symbiotic nitrogen fixation within nitrogen-fixing clade (NFC) plants is thought to have arisen from a single gain followed by massive losses in the genomes of ancestral non-nodulating plants. However, molecular evidence supporting this model is limited. Here, we confirm through bioinformatic analysis that NODULES WITH ACTIVATED DEFENSE1 (NAD1) is present only in NFC plants and is thus an NFC-specific gene. Moreover, NAD1 was specifically expressed in nodules. We identified three conserved nodulation-associated cis-regulatory elements (NACE1-3) in the promoter of LjNAD1 from Lotus japonicus that are required for its nodule specific expression. A survey of NFC plants revealed that NACE1 and NACE2 are specific to the Fabales and Papilionoideae, respectively, while NACE3 is present in all NFC plants. Moreover, we found that nodule inception (NIN) directly binds to all three NACEs to activate NAD1 expression. Mutation of L. japonicus LjNAD1 resulted in the formation of abnormal symbiosomes with enlarged symbiosome space and frequent breakdown of bacteroids in nodules, resembling phenotypes reported for Medicago truncatula Mtnad1 and Mtnin mutants. These data point to NIN-NAD1 as an important module regulating rhizobial accommodation in nodules. The regulation of NAD1 by NIN in the NFC ancestor represent an important evolutionary adaptation for nodulation., Competing Interests: Conflict of interest statement. Authors declare no competing interests., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society of Plant Biologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)
- Published
- 2024
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