Studies have shown that some microorganisms autochthonous from stressful environments are bene-
ficial when used with autochthonous plants, but these microorganisms rarely have been tested with
allochthonous plants of agronomic interest. This study investigates the effectiveness of drought-adapted
autochthonous microorganisms [Bacillus thuringiensis (Bt) and a consortium of arbuscular mycorrhizal
(AM) fungi] from a degraded Mediterranean area to improve plant growth and physiology in Zea mays
under drought stress. Maize plants were inoculated or not with B. thuringiensis, a consortium of AM fungi
or a combination of both microorganisms. Plants were cultivated under well-watered conditions or
subjected to drought stress. Several physiological parameters were measured, including among others,
plant growth, photosynthetic efficiency, nutrients content, oxidative damage to lipids, accumulation of
proline and antioxidant compounds, root hydraulic conductivity and the expression of plant aquaporin
genes. Under drought conditions, the inoculation of Bt increased significantly the accumulation of nutrients.
The combined inoculation of both microorganisms decreased the oxidative damage to lipids and
accumulation of proline induced by drought. Several maize aquaporins able to transport water, CO2 and
other compounds were regulated by the microbial inoculants. The impact of these microorganisms on
plant drought tolerance was complementary, since Bt increased mainly plant nutrition and AM fungi
were more active improving stress tolerance/homeostatic mechanisms, including regulation of plant
aquaporins with several putative physiological functions. Thus, the use of autochthonous beneficial
microorganisms from a degraded Mediterranean area is useful to protect not only native plants against
drought, but also an agronomically important plant such as maize.