Biocontrol of soil borne diseases by plant growth promoting rhizobacteria

Biological control has received increasing interest in recent decades as one of the alternatives to chemical pesticides in the field of plant disease control, especially after the increased awareness of the dangers of pesticides to the environment in general and human health in particular, and the emergence of resistance to pesticides in some causes. Biological control is defined as any conditions or procedures in which a particular organism or substances produced from a living organism are used to reduce infection with a particular pathogen. Plant growth promoting rhizobacteria (PGPR) are able to stimulate growth and resistance against plant diseases when they are able to have a positive effect on the plant health, and then demonstrate good competitive qualities and capabilities over existing rhizosphere communities. PGPR affects plant growth improvement by fixing atmospheric nitrogen, siderophore production dissolving insoluble phosphates, and releasing hormones. In this review, we tried to focus on the potential effects of PGPR as an effective and safe technique for plant disease resistance. PGPR play a major role in plant disease resistance through induced systemic resistance (ISR), antibiotics, hydrogen cyanide, Lytic enzyme, degradation of toxins, competition for nutrients, and parasitism.