School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK.
Warwick Medical School, University of Warwick, Coventry, CV4 7AL, UK.
Microbiome. 2023 Jul 3;11(1):146. doi: 10.1186/s40168-023-01592-0.
Despite the knowledge that the soil-plant-microbiome nexus is shaped by interactions amongst its members, very little is known about how individual symbioses regulate this shaping. Even less is known about how the agriculturally important symbiosis of nitrogen-fixing rhizobia with legumes is impacted according to soil type, yet this knowledge is crucial if we are to harness or improve it. We asked how the plant, soil and microbiome are modulated by symbiosis between the model legume Medicago truncatula and different strains of Sinorhizobium meliloti or Sinorhizobium medicae whose nitrogen-fixing efficiency varies, in three distinct soil types that differ in nutrient fertility, to examine the role of the soil environment upon the plant-microbe interaction during nodulation.
The outcome of symbiosis results in installment of a potentially beneficial microbiome that leads to increased nutrient uptake that is not simply proportional to soil nutrient abundance. A number of soil edaphic factors including Zn and Mo, and not just the classical N/P/K nutrients, group with microbial community changes, and alterations in the microbiome can be seen across different soil fertility types. Root endosphere emerged as the plant microhabitat more affected by this rhizobial efficiency-driven community reshaping, manifested by the accumulation of members of the phylum Actinobacteria. The plant in turn plays an active role in regulating its root community, including sanctioning low nitrogen efficiency rhizobial strains, leading to nodule senescence in particular plant-soil-rhizobia strain combinations.
The microbiome-soil-rhizobial dynamic strongly influences plant nutrient uptake and growth, with the endosphere and rhizosphere shaped differentially according to plant-rhizobial interactions with strains that vary in nitrogen-fixing efficiency levels. These results open up the possibility to select inoculation partners best suited for plant, soil type and microbial community. Video Abstract.
尽管人们知道土壤-植物-微生物组的联系是由其成员之间的相互作用形成的，但对于单个共生体如何调节这种形成过程知之甚少。对于农业上重要的固氮根瘤菌与豆科植物的共生体如何根据土壤类型受到影响，人们了解得更少，但如果我们要利用或改进这种共生体，就必须了解这些知识。我们研究了在三种不同的土壤类型中，模型豆科植物紫花苜蓿与固氮效率不同的根瘤菌菌株（中华根瘤菌和慢生根瘤菌）共生时，植物、土壤和微生物组是如何被调节的，这三种土壤类型在养分丰度上存在差异，以研究土壤环境在根瘤形成过程中对植物-微生物相互作用的作用。
共生的结果是安装了一个潜在有益的微生物组，导致养分吸收的增加，而不是简单地与土壤养分丰度成正比。包括 Zn 和 Mo 在内的许多土壤肥力因素，而不仅仅是经典的 N/P/K 养分，与微生物群落的变化有关，并且可以在不同的土壤肥力类型中看到微生物组的变化。根内生区是受这种根瘤菌效率驱动的群落重塑影响更大的植物微生境，这表现为放线菌门成员的积累。反过来，植物在调节其根际群落方面也发挥着积极作用，包括制裁低氮效率的根瘤菌菌株，导致特定植物-土壤-根瘤菌菌株组合的根瘤衰老。
微生物组-土壤-根瘤菌的动态强烈影响植物的养分吸收和生长，其中内生区和根际区根据植物与固氮效率水平不同的菌株的相互作用而有差异。这些结果为选择最适合植物、土壤类型和微生物群落的接种伙伴提供了可能性。视频摘要。
