Recently, the Innovation Team of Agricultural Microbial Resources of the Institute of Agricultural Resources and Regional Planning (IARRP) of the Chinese Academy of Agricultural Sciences (CAAS) was invited to publish a comprehensive review article in FEMS Microbiology Reviews, summarizing the mechanisms of root colonization by plant beneficial rhizobacteria.

The colonization of roots by beneficial rhizobacteria is of great significance for the health and growth of plants, and can be developed to support the production of microbial fertilizers for sustainable agriculture. Compared to the two typical plant-associated microbial groups -- namely plant soilborne pathogens and plant symbiotic microorganisms (such as rhizobia and mycorrhizal fungi) -- the colonization mechanisms of rhizobacteria that closely interact with plants without forming a symbiotic relationship are still not deeply understood, despite being the main force in the agricultural microbial production.

Taking the process of root colonization by plant beneficial rhizobacteria as a clue, the article provides a detailed summary of the bacterial signal perception and microbial molecular regulation pathways involved in chemotaxis, root surface adhesion, biofilm formation on the root surface, and endophytism. The influence and mechanisms of root exudates and plant immunity on root colonization are discussed. The article also highlights the promoting effect of "cry for help" responses on the colonization of beneficial rhizobacteria and compares the similarities and differences between the colonization processes of the non-symbiotic rhizobacteria, the plant soilborne pathogens, and the plant symbiotic microorganisms in the rhizosphere. Finally, the article proposes strategies for enhancing the colonization capacity of plant beneficial rhizobacteria through regulation and domestication.

Figure 1: Plant Beneficial Bacteria Colonization Process

Figure 2: Similarities and Differences in Rhizosphere Colonization between Non-symbiotic Beneficial Microorganisms and Plant Pathogens and Symbiotic Microorganisms.

The article is co-first-authored by Professor Yunpeng Liu from the Innovation Team of Agricultural Microbial Resources of the IARRP, and Associate Professor Zhihui Xu from Nanjing Agricultural University. It is correspondingly authored by Professor Ruifu Zhang.

Paper link: https://doi.org/10.1093/femsre/fuad066