Fig. 3.

Schematic representation of the stimulation of plant growth by a PGPB containing ACC deaminase. Stress increases both IAA and ethylene synthesis within the plant ultimately decreasing plant growth. With PGPB strains that contain ACC deaminase, ethylene levels are decreased thereby relieving some of the growth inhibition that increased ethylene causes. This enables the bacterial IAA to continue to promote plant growth. Thus, PGPB that produce both IAA and ACC deaminase lower the extent that a wide range of environmental stresses inhibit plant growth. SAM S-adenosyl-methionine. These PGPB protect plants against the inhibitory effects of ethylene-producing stresses that include drought, flooding, temperature extremes, high salt, metal and organic contaminants, insect and nematode predation, and both fungal and bacterial phytopathogens