Cadmium (Cd) stress is an obstacle for crop production, quality crops, and sustainable agriculture. An important role is played by the application of eco-friendly approaches to improve plant growth and stress tolerance. In the current study, a pre-sowing seed treatment with Rhizobium leguminosarum strains, isolated from the leguminous plants Phaseolus vulgaris (strain Pvu5), Vicia sylvatica (strain VSy12), Trifolium hybridium (strain Thy2), and T. pratense (strain TPr4), demonstrated different effects on wheat (Triticum aestivum L.) plant growth under normal conditions. Among all tested strains, Thy2 significantly increased seed germination, seedling length, fresh and dry biomass, and leaf chlorophyll (Chl) content. Further analysis showed that Thy2 was capable of producing indole-3-acetic acid and siderophores and fixing nitrogen. Under Cd stress, Thy2 reduced the negative effect of Cd on wheat growth and photosynthesis and had a protective effect on the antioxidant system. This was expressed in the additional accumulation of glutathione and proline and the activation of glutathione reductase. In addition, Thy2 led to a significant reduction in oxidative stress, which was evidenced by the data on the stabilization of the ascorbate content and the activity of ascorbate peroxidase. In addition, Thy2 markedly reduced Cd-induced membrane lipid peroxidation and electrolyte leakage in the plants. Thus, the findings demonstrated the ability of the R. leguminosarum strain Thy2, isolated from T. hybridium nodules, to exert a growth-promoting and anti-stress effect on wheat plants. These results suggest that the Thy2 strain may enhance wheat plant growth by mitigating Cd stress, particularly through improving photosynthesis and antioxidant capacity and reducing the severity of oxidative damage. This may provide a basic and biological approach to use the Thy2 strain as a promising, eco-friendly candidate to combat Cd stress in wheat production.

Plants are constantly faced with both abiotic and biotic stresses, which seriously reduce their productivity. We evaluated the potential of endophytic bacteria Bacillus subtilis (strain 10-4) alone, and when mixed with salicylic acid (SA), to meliorate drought and Fusarium root rot (FRR) stresses in Triticum aestivum L. All microbiological, molecular, and physio-biochemical parameters were assessed using classical and modern methods. The findings demonstrated B. subtilis 10-4 alone, and especially mixed with SA, significantly improved wheat growth and ameliorated the damaging influence of drought, FRR, and drought + FRR. An important contribution to observed growth-stimulating and protective effects of B. subtilis 10-4 and SA on plants revealed the ability of bacteria to produce auxins, siderophores, lipopeptides surfactin, and to colonize internal plant tissues. Additionally, bio-priming of seeds with B. subtilis 10-4 alone, and especially mixed with SA, decreased stress-induced (drought, FRR, drought + FRR) lipid peroxidation and amino acid proline accumulation in plants, thereby indicating a protective effect on plant cells against reactive oxygen species and osmotic damages. Current research provides novel insights into the potential and mechanism of B. subtilis 10-4 and SA in the mitigation of combined drought + FRR stresses in wheat.

We obtained constructs pHT01-GFP and pHT43-RFP. Recombinant plasmids were transferred into endophytic Bacillus subtilis (strains 10-4 and 26D).

Maximum growth-stimulating and protective effect of endophytic bacteria Bacillus subtilis 10-4 on wheat plants under normal and drought stress conditions reached when its applied in composition with salicylic acid were discovered.