Seed-Biopriming of Durum Wheat with Diazotrophic Plant Browth Promoting Bacteria (PGPB) Enhanced Tolerance to Fusarium Head Blight (FHB) and Salinity Stress

Abstract Background The use of bioinoculants based on plant growth-promoting bacteria (PGPB) to promote plant growth under biotic and abiotic stresses is in full expansion. To our knowledge much work has not been, thus far, done on seed-biopriming of durum wheat for tolerance to biotic and abiotic stresses. In the present work, we report detailed account of the effectiveness a potent bacterial strain with proven plant growth-promoting ability and antimicrobial activity. The isolate was selected following screening of several bacterial strains isolated from halophytes that grow in a coastal saline soil in Tunisia for their role in enhancing durum wheat tolerance to both salinity stress and head blight disease.Results Accordingly, Bacillus strains MA9, MA14, MA17 and MA19 were found to have PGPB characteristics as they produced indole-3-acetic acid, siderophores and lytic enzymes, fixed free atmospheric nitrogen, and solubilized inorganic phosphate, in vitro . The in vivo study that involved in planta inoculation assays under control (25 mM NaCl) and stress (125 mM NaCl) conditions indicated that all PGPB strains significantly ( P < 0.05) increased the total plant length, dry weight, root area, seed weight, nitrogen, protein and total mineral content. On the other hand, strain MA17 reduced Fusarium Head Blight (FHB) disease incidence in wheat explants by 64.5%, showing that the strain has antifungal activity as was also displayed by in vitro inhibition study.Conclusions Both in vitro and in vivo studies showed that MA9, MA14 MA9, MA14, MA17 and MA19 strains were able to play the PGPB role. Yet, biopriming with Bacillus strain MA17 offered the highest bioprotection against FHB, plant growth promotion, and salinity tolerance. Hence, the MA17 strain should further be evaluated under field condition and formulated for commercial production. Besides, the strain could further be evaluated for its potential role in bioprotection and growth promotion of other crop plants. We believe, the strain has potential to significantly contribute to wheat production in the arid and semi-arid region, especially the salt affected Middle Eastern Region, besides its potential role in improving wheat production under biotic and abiotic stresses in other parts of the world.