Molecular aspects of plant growth promotion and protection by Bacillus subtilis

Bacillus subtilis is one of the most widely studied plant-growth promoting rhizobacteria. It is able to both promote plant growth as well as control plant pathogens through diverse mechanisms, including the improvement of nutrient availability and alteration of phytohormone homeostasis as well as the production of antimicrobials and triggering induced systemic resistance, respectively.

Even though its benefits for crop production have been recognized and studied extensively under laboratory conditions, the success of its application in fields varies immensely. It is widely accepted that agricultural application of B. subtilis often fails because the bacteria are not able to persist in the rhizosphere.

With this in mind, bacterial colonization of plant roots is a crucial step in the interaction between microbe and plant and seems therefore to be of great importance for its growth promotion and biocontrol effects. A successful root colonization depends thereby on both bacterial traits, including motility and biofilm formation, as well as on a signal interplay with the plant.

This review addresses the current knowledge about plant-microbial interactions of the B. subtilis species, including the various mechanisms for supporting plant growth as well as the necessities for the establishment of the relationship.