2. Modes of action of BACs

The main modes of action of BCAs are antibiosis, competition, mycoparasitism, and stimulation or enhancement of plant defense [7]. BCAs usually relay on more than one mode of action to antagonize the pathogen i.e. presence of one dominant mode of action does not exclude the others. Table 1 summarizes the reported modes of action used against mycotoxigenic fungi in each crop.

(i) Antibiosis encompasses the production of secondary metabolites such as antibiotics [19–21], lytic enzymes [22] and other proteins [23] that are able to suppress the growth, weaken the virulence or kill the pathogenic fungi.

(ii) Competition occurs when two or more fungi compete for the same essential nutrients required for their growth and development [24, 25]. Another type of competition is exclusion by occupying the same niche [26, 27].

(iii) Mycoparasitism or hyperparasitism is a direct parasitic attack of one fungus by another one which eventually causes death of the host pathogen [28–30].

(iv) Colonization of the plant, by beneficial micro-organisms can trigger local or systemic defense responses, thus enhancing resistance against plant pathogens [31, 32].
