Dual RNA-Seq Analysis Pinpoints a Balanced Regulation between Symbiosis and Immunity in <i>Medicago truncatula</i>-<i>Sinorhizobium meliloti</i> Symbiotic Nodules
Legume–rhizobial symbiosis initiates the formation of root nodules, within which rhizobia reside and differentiate into bacteroids to convert nitrogen into ammonium, facilitating plant growth. This process raises a fundamental question: how is plant immunity modulated within nodules when exposed to...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2023-11-01
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| Series: | International Journal of Molecular Sciences |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1422-0067/24/22/16178 |
| Summary: | Legume–rhizobial symbiosis initiates the formation of root nodules, within which rhizobia reside and differentiate into bacteroids to convert nitrogen into ammonium, facilitating plant growth. This process raises a fundamental question: how is plant immunity modulated within nodules when exposed to a substantial number of foreign bacteria? In <i>Medicago truncatula</i>, a mutation in the <i>NAD1</i> (<i>Nodules with Activated Defense 1</i>) gene exclusively results in the formation of necrotic nodules combined with activated immunity, underscoring the critical role of <i>NAD1</i> in suppressing immunity within nodules. In this study, we employed a dual RNA-seq transcriptomic technology to comprehensively analyze gene expression from both hosts and symbionts in the <i>nad1-1</i> mutant nodules at different developmental stages (6 dpi and 10 dpi). We identified 89 differentially expressed genes (DEGs) related to symbiotic nitrogen fixation and 89 DEGs from <i>M. truncatula</i> associated with immunity in the <i>nad1-1</i> nodules. Concurrently, we identified 27 rhizobial DEGs in the <i>fix</i> and <i>nif</i> genes of <i>Sinorhizobium meliloti</i>. Furthermore, we identified 56 DEGs from <i>S. meliloti</i> that are related to stress responses to ROS and NO. Our analyses of nitrogen fixation-defective plant <i>nad1-1</i> mutants with overactivated defenses suggest that the host employs plant immunity to regulate the substantial bacterial colonization in nodules. These findings shed light on the role of <i>NAD1</i> in inhibiting the plant’s immune response to maintain numerous rhizobial endosymbiosis in nodules. |
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| ISSN: | 1661-6596 1422-0067 |