Rhizobia and legumes form a symbiotic relationship resulting in the formation of root structures known as nodules, where bacteria fix nitrogen. Legumes release flavonoids that are detected by the rhizobial nodulation (Nod) protein NodD, initiating the transcriptional activation of nod genes and subsequent synthesis of Nod Factors (NFs). NFs then induce various legume responses essential for this symbiosis. Although evidence su...

Motility and chemotaxis are crucial processes for soil bacteria and plant–microbe interactions. This applies to the symbiotic bacterium Rhizobium leguminosarum , where motility is driven by flagella rotation controlled by two chemotaxis systems, Che1 and Che2. The Che1 cluster is particularly important in free‐living motility prior to the establishment of the symbiosis, with a che1 mutant delayed in nodulation and reduced in n...

Ecosystem engineers can generate hotspots of ecological structure and function by facilitating the aggregation of both resources and consumers. However, nearly all examples of such engineered hotspots come from long‐lived foundation species, such as marine and freshwater mussels, intertidal cordgrasses, and alpine cushion plants, with less attention given to small‐bodied and short‐lived animals. Insects often have rapid life c...

Engineering signalling between plants and microbes could be exploited to establish host‐specificity between plant‐growth‐promoting bacteria and target crops in the environment. We previously engineered rhizopine‐signalling circuitry facilitating exclusive signalling between rhizopine‐producing ( RhiP ) plants and model bacterial strains. Here, we conduct an in‐depth analysis of rhizopine‐inducible expression in bacteria. We ch...

The plant common symbiosis signalling (SYM) pathway has shared function between interactions with rhizobia and arbuscular mycorrhizal fungi, the two most important symbiotic interactions between plants and microorganisms that are crucial in plant and agricultural yields. Here, we determine the role of the plant SYM pathway in the structure and abundance of the microbiota in the model legume Medicago truncatula and whether this...

Most nitrogen (N) lost to the environment from grazed grassland is produced as a result of N excreted by livestock, released in the form of nitrous oxide (N 2 O) emissions, nitrate leaching and ammonia volatilisation. In addition to the N fertiliser applied, excreta deposited by grazing livestock constitute a heterogeneous excess of N, creating spatial hotspots of N losses. This study presents a yearlong N 2 O emissions map fr...

Background and aims Plant and bacteria are able to synthesise proline, which acts as a compound to counteract the negative effects of osmotic stresses. Most methodologies rely on the extraction of compounds using destructive methods. This work describes a new proline biosensor that allows the monitoring of proline levels in a non-invasive manner in root exudates and nodules of legume plants. Methods The proline biosensor was c...

Summary Rhizobium leguminosarum has two high‐affinity Mn 2+ transport systems encoded by sitABCD and mntH . In symbiosis, sitABCD and mntH were expressed throughout nodules and also strongly induced in Mn 2+ ‐limited cultures of free‐living cells. Growth of a sitA mntH double mutant was severely reduced under Mn 2+ limitation and sitA and mntH single mutants were more sensitive to oxidative stress. The double sitA mntH mutant...