Developed BL-EF to acquire plant growth-promoting functions under salt stress by introducing the ACC deaminase gene.

The application of plant growth-promoting rhizobacteria (PGPR) is a novel and effective strategy to ameliorate soil salinity and increase agricultural productivity. ACC deaminase (ACCD) in PGPR plays a key role in alleviating salt stress and promoting plant growth. This study aimed to investigate the potential of ACCD-producing strain BL-EF to mitigate salt stress in tomato plants. The ACCD gene was introduced into the non-PGPR Escherichia coli to successfully construct to construct BL-EF and produce catalytically active ACCD. The results showed that strain BL-EF significantly increased the height of tomato plants by 30.94% and 44.63%, under both normal and salt stress conditions, respectively. Strain BL-EF also modulated the photosynthetic pigmentation process in plants, promoting plant growth and increasing tomato tolerance to salt stress. The osmoregulatory system improved and the antioxidant enzyme activities increased to counteract reactive oxygen species-induced activities inoculated with BL-EF compared with those not inoculated with BL-EF. In addition, the inoculation with BL-EF strains increased soil enzyme activities and enhanced nutrients availability in the soil for plants uptake. In conclusion, the inoculation of ACC deaminase-producing strain BL-EF holds immense potential to alleviate salt stress in tomato plants, offering significant benefits to the agricultural sector.