Raising Beet Tolerance to Salinity through Bioaugmentation with Halotolerant Endophytes

Increasing land salinization in recent decades has led to a decrease in crop productivity worldwide. We hypothesized that bioaugmentation of beetroot (Beta vulgaris) with halotolerant endophytic bacterial strains isolated from the obligatory halophytic plant Salicornia europaea L. may mitigate salt stress in new host plants. Therefore, we investigated the effects of inoculation with Pseudomonas stutzeri ISE12 or Kushneria marisflavi CSE9 on B. vulgaris growth in substrates enriched with various NaCl concentrations (0, 50, 150, 300 mM). The results of this study indicated that bioaugmentation with either bacteria resulted in improved growth parameters and increased chlorophyll content, as well as decreased proline and hydrogen peroxide concentrations, in B. vulgaris organs. However, K. marisflavi CSE9 was more efficient in achieving salt stress mitigation than P. stutzeri ISE12. In conclusion, the range of salinity tolerance seems to be a key parameter in the selection of strains for beet inoculation. The selected halotolerant endophytes (P. stutzeri ISE12 and K. marisflavi CSE9) isolated from the roots of obligatory halophytic S. europaea may be employed for plant growth promotion, especially in saline areas, and have potential applications in sustainable agriculture.