How do beneficial microbes protect plants against plant root pathogens?
The mechanisms by which beneficial microorganisms control diseases caused by plant root pathogens are not completely understood. Three modes of action can contribute to the protective activity of beneficial microbes: (1) competition for nutrients in soil and the rhizosphere, (2) competition for infection sites and root colonization, and/or (3) induced systemic resistance . Pathogenic and beneficial microorganisms can occupy the same ecological niche, indicating that competition for infection sites is certainly one of the modes of action involved in bio-protection (Salerno et al. 2000). However, competition for infection sites alone does not necessarily fully explain all the bio-control activity of beneficial microbes. Additionally, many microorganisms have the ability to induce systemic resistance against various pests and diseases. Induced resistance is defined as an enhancement of the plant’s defensive capacity against a broad spectrum of pathogens and pests that is acquired after ap
