Modulation of Triticum aestivum L. tolerance to combined abiotic/biotic stresses by endophytic plant growth promoting bacteria Bacillus subtilis

Wheat (Triticum aestivum L.) is one of the most important cereal food crops worldwide. Various abiotic and biotic stresses or their combinations lead to crop losses (up to 50-82%) and pose a serious threat to the agricultural industry and food security. Plant growth-promoting endophytic bacteria Bacillus subtilis are considered as a bioactive and eco-friendly strategy for plant protection. Earlier, we have shown B. subtilis 10-4 has a growth-promoting and anti-stress effect on wheat under water deficiency. Here, we investigated the effect of B. subtilis 10-4 and B. subtilis 10-4+salicylic acid (SA) on growth and tolerance of wheat (cv. ‘Omskaya-35’) to combined drought (12%PEG) and Fusarium culmorum. 12%PEG and F. culmorum led to yellowing of leaves (in addition to traces of the root damages). Inoculation with 10-4 and especially 10-4+SA reduced the fusarium development in wheat under drought. Similar effects were revealed for growth parameters. Also, 10-4 (especially 10-4+SA) reduces stress-induced lipid peroxidation (MDA). Such physiological effect may be connected with the ability of strain 10-4 to colonize the internal tissues of host-plant and regulate metabolism from the inside. The obtained construct based on the plasmid pHT01 and the green fluorescent protein (gfp) gene, by which was modified the strain 10-4, will allow revealing the nature of the symbiotic relationships between the strain 10-4 and host-plant. The findings indicate that application B. subtilis 10-4 and its composition with SA may be an effective strategy to increase wheat tolerance to the combined abiotic/biotic stresses.