The Enterobacter sp. SA187 stimulates stress-responsive genes and promotes salt and heat stress tolerance in tomato plants

Enterobacter sp. SA187, is a plant growth-promoting bacterium (PGPB) with potential to enhance abiotic stress tolerance in various crops. This study evaluated the impact of inoculation of SA187 to salinity and heat stress tolerance of Solanum lycopersicum L, tomato. Different alterations in the physiological, biochemical and molecular responses against the salt and heat stress due to the beneficial association of tomato plants with SA187 were investigated. Colonization by SA187 significantly enhanced tomato plants growth under both saline and heat stress condition. It induced an enhancement of > 90 % in the morphological and physiological processes resulting in an increased root hair growth and higher plant biomass. The inoculation also caused a 65 % decline in Na⁺/K⁺ ratio, increased chlorophyll content and improved the antioxidant enzyme activity of Superoxidase dismutase (SOD), Peroxidase (POD), and Catalase (CAT), particularly under salt and heat stress conditions. The RNA-seq analysis produced clean reads that ranged from 33,812,161 to 44,114,539 across the different groups of treatment, which were successfully assembled into 35,825 annotated genes. Transcriptomic analysis of the genes involved in the enhancement of the physiological and biochemical processes revealed at least a 2-fold increase in the expression of NHX3 and ERF4 in leaves, SOS2, SOS4, and SULTR3;5 in leaves and roots. For heat stress, SA187-colonized tomato plants displayed higher expression of heat shock protein genes in leaves such as HSP17.4B, HSP17.6, HSP22.0, and HSP26.5. These findings show the possibility of using the Enterobacter sp. SA187 as a sustainable solution for enhancing crop tolerance and productivity in challenging environmental conditions.