REVIEW article
Front. Microbiol.
Sec. Microbial Symbioses
Volume 16 - 2025 | doi: 10.3389/fmicb.2025.1622262
This article is part of the Research TopicMicrobial Interactions Across Species: Shaping Pathogenesis, Symbiosis, and Ecosystem DynamicsView all 5 articles
Antagonism Within Mutualism: Host Control of Symbionts Through Nodule-Specific
Provisionally accepted
- Washington State University, Pullman, United States
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Legumes (Fabaceae) have developed a symbiotic relationship with nitrogen fixing bacteria called rhizobia to meet their nitrogen needs. Legumes recruit rhizobia from the soil, house them in root organs called nodules, and manipulate bacterial metabolism providing carbon and receiving bacterially-fixed nitrogen in return. One mechanism of host control is through a family of antimicrobial peptides that only appears in the Inverted Repeat Lacking Clade of the legumes (IRLC), though the Dalbergioid clade has similar peptides. They are named Nodule-specific Cysteine Rich (NCR) peptides due to their exclusive expression in the nodule during symbiosis and the shared 4 or 6 cysteine residue motif. These genes and subsequent proteins vary in number, sequence, and function but evolutionary genomics research shows that they are adapted from the plant immune system for the new function of symbiont manipulation. In this review we present the current understanding of NCR peptide biology, expression, and function. We examine NCR genomic and biochemical features, and explore their roles in shaping symbiotic outcomes. Finally, we discuss emerging applications and key open questions. Understanding host manipulation of bacterial symbionts within plant tissues gives researchers targets for engineering more efficient nitrogen fixing symbioses. In addition, NCR peptides show promise as therapeutic agents with potential to control both plant and animal pathogens.
Keywords: Symbiosis, legume-rhizobia, Mutualism and antagonism, plant peptides, antimicrobial peptides, gene family evolution Style Definition: Heading 6 Style Definition: Heading 5 Style Definition: Heading 4 Style Definition: Heading 3 Style Definition: Heading 2 Style Definition: Heading 1 Moved (insertion) [1] Formatted: Font: Bold symbiosis, symbiotic relationships Indent: First line: 0.5" Formatted: Font: Italic, No underline investigated a M Font: Italic
Received: 02 May 2025; Accepted: 12 Aug 2025.
Copyright: © 2025 Eaker, Rowe and Friesen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Maren Friesen, Washington State University, Pullman, United States
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