Amrhein Anton, Zhang Mingxiao, Hacquard Stéphane, Heintz-Buschart Anna, Wippel Kathrin
Department of Plant-Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany.
Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands.
PLoS Biol. 2025 Jul 15;23(7):e3002882. doi: 10.1371/journal.pbio.3002882. eCollection 2025 Jul.
The plant root microbiota is crucial for nutrient acquisition, development, and disease suppression. Although commensal bacteria display host preference, their beneficial impact on their cognate host and mechanisms of species selection by the plant are still unclear. We use bacterial culture collections derived from the two model species Arabidopsis thaliana (At) and Lotus japonicus (Lj) to design synthetic communities (SynComs) and test their protective function upon exposure of At Col-0 to the detrimental root-colonizing At-derived Pseudomonas isolate R401. Lj-derived SynComs were fully protective, whereas At-derived SynComs displayed full protective activity only towards a R401 mutant impaired in the production of inhibitory exometabolites. The protective phenotypes were associated with a reduced titer of the R401 opportunistic pathogen. In vitro antagonist assays, in planta and in vitro bacterial community profiling, as well as strain-swapping and strain-dropout experiments revealed that competition among commensal Pseudomonas strains and R401 determines the success of the opportunist, independent of the original host or the phylogeny of the commensals. Furthermore, we determine the carbon utilization potential of these isolates, which may explain the competition with the detrimental strain and the role of host-secreted compounds. Our results provide evidence that intra-genus interactions within SynComs modulate plant health and disease, and that an individual beneficial strain can be sufficient to outcompete an opportunistic relative. This has implications for the successful development of beneficial microbial consortia for agriculture.
植物根系微生物群对养分获取、生长发育和病害抑制至关重要。尽管共生细菌表现出宿主偏好，但它们对同源宿主的有益影响以及植物选择物种的机制仍不清楚。我们利用从两种模式植物拟南芥（At）和百脉根（Lj）中获得的细菌培养物来设计合成群落（SynComs），并在将At Col-0暴露于有害的根部定殖的At来源的假单胞菌分离株R401时测试它们的保护功能。Lj来源的SynComs具有完全的保护作用，而At来源的SynComs仅对抑制性胞外代谢产物产生受损的R401突变体表现出完全的保护活性。保护表型与R401机会致病菌的滴度降低有关。体外拮抗试验、植物体内和体外细菌群落分析，以及菌株交换和菌株缺失实验表明，共生假单胞菌菌株与R401之间的竞争决定了机会致病菌的成败，这与原始宿主或共生菌的系统发育无关。此外，我们确定了这些分离株的碳利用潜力，这可能解释了与有害菌株的竞争以及宿主分泌化合物的作用。我们的结果提供了证据，表明SynComs内的属内相互作用调节植物健康和疾病，并且单个有益菌株就足以胜过机会致病菌。这对农业有益微生物群落的成功开发具有重要意义。
