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Nodule cysteine-rich peptides maintain a working balance during nitrogen-fixing symbiosis

Nature Plants volume 3, Article number: 17048 (2017) Cite this article

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Abstract

The nitrogen-fixing symbiosis between legumes and rhizobia is highly relevant to human society and global ecology. One recent breakthrough in understanding the molecular interplay between the plant and the prokaryotic partner is that, at least in certain legumes, the host deploys a number of antimicrobial peptides, called nodule cysteine-rich (NCR) peptides, to control the outcome of this symbiosis. Under this plant dominance, the bacteria are subject to the sub-lethal toxicity of these antimicrobial peptides, resulting in limited reproductive potential. However, recent genetic studies have added unexpected twists to this mechanism: certain NCR peptides are essential for the bacteria to adapt to the intracellular environment needed for a successful symbiosis, and the absence of these peptides can break down the mutualism. Meanwhile, some rhizobial strains have evolved a peptidase to specifically degrade these antimicrobial peptides, allowing the bacteria to escape host control. These findings challenge the preconceptions about ‘antimicrobial’ peptides, supporting the notion that their role in biotic interactions extends beyond toxicity to the microbial partners.

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Figure 1: Rhizobia bacteroids undergo differentiation inside Medicago nodules.
Figure 2: Representative sequences of M. truncatula NCR peptides.
Figure 3: Model for the functions of NCR169, NCR211, and the HrrP peptidase in symbiotic nodule cells.
Figure 4: A proposed relationship between the effect of NCR peptides, the fate of bacteroids and the outcome of the symbiosis.

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Acknowledgements

This work is supported by USDA National Institute of Food and Agriculture AFRI award 2015-67013-22915 and National Science Foundation IOS program Award 1557994.

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Authors and Affiliations

  1. Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, 01003, Massachusetts, USA

    Huairong Pan & Dong Wang

  2. Plant Biology Graduate Program, University of Massachusetts Amherst, 01003, Massachusetts, USA

    Dong Wang

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Correspondence to Dong Wang.

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Pan, H., Wang, D. Nodule cysteine-rich peptides maintain a working balance during nitrogen-fixing symbiosis. Nature Plants 3, 17048 (2017). https://doi.org/10.1038/nplants.2017.48

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