Figure 2. PGPB associated to plants stimulate growth during drought. Physiological plant processes (gray arrows) and mechanisms (white arrows) change according to stimulations determined by the associated PGPB (in blue in the plant drawing) in response to drought. On the left and the right sides of the plant drawing are reported the intensities of processes and mechanisms under water stress, in the absence or presence of the PGPB. For each process and mechanism represented in the same line, the lengths of the arrows indicate reduced/increased physiological responses. The black boxes indicate the specific promoting activities exerted by the PGPB in relation to the specific processes or mechanisms.