How Soil Bacteria Genes Influence Plant Root Microbiome Formation

Jenn Hoskins
15th May, 2024

How Soil Bacteria Genes Influence Plant Root Microbiome Formation

The experimental design (a) and timeline (b) outline a comparison between the effects of wild-type Bacillus subtilis and a mutant lacking key biofilm genes on the tomato rhizosphere microbiome under varying levels of soil biodiversity.

Image adapted from: Nishisaka et al. / CC BY (Source)

Key Findings

  • The study by Embrapa focused on tomato plants grown in soils with varying microbial diversity to understand how Bacillus subtilis affects the rhizosphere microbiome and plant health
  • Wild-type B. subtilis (UD1022) was more effective at promoting beneficial rhizosphere microbiomes and enhancing plant growth compared to the mutant strain lacking EPS and TasA
  • The ability of B. subtilis to produce EPS and TasA is crucial for its effectiveness in promoting a healthy microbial community around plant roots
The relationship between plants and the diverse microbial communities in their rhizosphere (the soil region influenced by plant roots) is crucial for plant health and growth. The rhizosphere microbiome aids in nutrient acquisition, provides defense against pests and diseases, and helps plants cope with environmental stresses[2][3]. However, the mechanisms through which plants influence the composition and function of these microbial communities are not fully understood. Recent research by Embrapa has provided new insights into how specific bacterial genes affect rhizosphere microbiome assembly and plant health, with a focus on the beneficial bacterium Bacillus subtilis[1]. Bacillus subtilis is known for its ability to promote plant growth and mitigate both abiotic (non-living environmental factors) and biotic (living organisms) stresses. This bacterium can be particularly effective in enhancing plant health by recruiting and maintaining beneficial microbial communities in the rhizosphere[2][3]. The study conducted by Embrapa aimed to investigate the role of exopolymeric genes in B. subtilis, specifically focusing on the wild-type strain UD1022 and a mutant strain UD1022eps−TasA, which is defective in producing exopolysaccharide (EPS) and TasA protein. EPS and TasA are important components of the biofilm matrix that B. subtilis forms. Biofilms are structured communities of microorganisms that adhere to surfaces and are embedded in a self-produced matrix of extracellular polymeric substances. These biofilms are crucial for the bacterium's ability to colonize the rhizosphere and interact with plant roots[4]. By creating a mutant strain lacking EPS and TasA production, the researchers aimed to understand how these components influence the assembly of the rhizosphere microbiome and, consequently, plant health. The study was conducted using tomato plants grown in soils with varying levels of microbial diversity. This approach allowed the researchers to observe how the presence or absence of EPS and TasA affected the microbiome under different environmental conditions. The results showed that the wild-type B. subtilis strain UD1022 was more effective at promoting a beneficial rhizosphere microbiome compared to the mutant strain UD1022eps−TasA. Specifically, the wild-type strain enhanced the abundance of beneficial microorganisms that support plant growth and defense, while the mutant strain was less effective in doing so. These findings highlight the importance of specific bacterial traits in shaping the rhizosphere microbiome. The ability of B. subtilis to produce EPS and TasA appears to be crucial for its effectiveness in promoting a healthy microbial community around plant roots. This aligns with previous research indicating that plants can actively recruit beneficial microbes to their rhizosphere to enhance their growth and defense mechanisms[2][3]. Moreover, this study underscores the potential impact of plant domestication on the rhizosphere microbiome. Modern crop cultivars often have reduced genetic diversity compared to their wild ancestors, which may affect their ability to establish beneficial microbial associations[3]. By understanding the specific microbial traits that contribute to a healthy rhizosphere, researchers can develop strategies to improve crop resilience and productivity. This could involve breeding plants that are better at recruiting beneficial microbes or engineering microbial strains with enhanced traits for biofilm formation and plant interaction. In conclusion, the study by Embrapa provides valuable insights into the role of exopolymeric genes in B. subtilis and their impact on rhizosphere microbiome assembly and plant health. The findings emphasize the importance of microbial traits such as EPS and TasA production in promoting beneficial plant-microbe interactions. This research not only advances our understanding of plant-microbe relationships but also offers potential avenues for improving agricultural practices and crop performance through microbiome management.

GeneticsBiochemPlant Science

References

Main Study

1) Role of Bacillus subtilis exopolymeric genes in modulating rhizosphere microbiome assembly

Published 14th May, 2024

https://doi.org/10.1186/s40793-024-00567-4

Related Studies

2) The rhizosphere microbiome and plant health.

https://doi.org/10.1016/j.tplants.2012.04.001

3) Impact of plant domestication on rhizosphere microbiome assembly and functions.

https://doi.org/10.1007/s11103-015-0337-7

4) The rhizosphere microbiome: significance of plant beneficial, plant pathogenic, and human pathogenic microorganisms.

https://doi.org/10.1111/1574-6976.12028


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