One of the main abiotic stresses that threaten the survival of wheat (Triticum spp. ) is drought. The present work aims to evaluate the ability of different plant growth promoting microorganisms (PGPMs) to alleviate the effects of dehydration in wheat and to understand the mechanisms involved. Wheat seeds (Triticum aestivum L. ssp. cv. ‘Galera’) inoculated with the strains Priestia megaterium CDFICOS₀1, Peribacillus frigoritolerans CDFICOS₀2, Pseudomonas canadensis CDFICOS₀3, Azotobacter chroococcum CDFICOS₀4 or Pichia kluyveri CDFICOS₀5 were exposed to prolonged drought by water shortage after which agronomic parameters, biochemical markers of abiotic stress and expression of genes related to plant response to water stress were measured. The behaviour of the PGPM strains evaluated varied in alleviating plant water stress, allowing two groups to be differentiated. The application of strains CDFICOS₀1, CDFICOS₀2 and CDFICOS₀3 resulted in an enhancement of crop production, with increases in aerial fresh biomass of 59%, 18%, and 38%, respectively, compared to the control. These strains also stimulated ethylene and/or abscisic acid metabolism. In contrast, strains CDFICOS₀4 and CDFICOS₀5 were also able to promote mechanisms related to the plant response to abiotic stress (MDA, proline, H2O2), but did not exert any physiological effect at plant level. In fact, they reduced the yield, with decreases in aerial fresh biomass of 43% and 21%, and in aerial dry biomass of 33% and 20%, respectively.
Anta-Fernández et al. (Tue,) studied this question.