Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, Massachusetts 01003, USA.
Plant Biology Graduate Program, University of Massachusetts Amherst, Massachusetts 01003, USA.
Nat Plants. 2017 May 4;3(5):17048. doi: 10.1038/nplants.2017.48.
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.
豆科植物与根瘤菌之间的固氮共生关系与人类社会和全球生态息息相关。最近，人们在理解植物与其原核伙伴之间的分子相互作用方面取得了一项突破，即在某些豆科植物中，宿主会利用多种被称为结瘤半胱氨酸丰富（NCR）肽的抗菌肽来控制这种共生关系的结果。在这种植物主导的情况下，细菌会受到这些抗菌肽的亚致死毒性的影响，从而导致其繁殖潜力受到限制。然而，最近的遗传研究为这一机制增添了意想不到的转折：某些 NCR 肽对于细菌适应成功共生所需的细胞内环境是必不可少的，而缺乏这些肽会破坏共生关系。同时，一些根瘤菌菌株已经进化出一种肽酶来专门降解这些抗菌肽，使细菌能够逃避宿主的控制。这些发现挑战了人们对“抗菌”肽的固有观念，支持了这样一种观点，即它们在生物相互作用中的作用不仅限于对微生物伙伴的毒性。
