Transplantation of rhizosphere microbiome from tomato enhances salinity stress tolerance in chilli and bell pepper

Salinity stress adversely affects plant growth and development, leading to reduced quality and yield. Traditional approaches, including chemical amendments and bioinoculants, often show limited effectiveness under natural conditions. To overcome these limitations, this study employed a top-down rhizosphere engineering approach through rhizosphere microbiome transplantation (RMT) to mitigate salinity stress. First, a salt stress-acclimatized microbiome was generated by repeated plant growth cycles (PGCs) through RMT by ramping up salinity levels for multiple PGCs in a salt-susceptible tomato cultivar. Then, the generated salt stress-acclimatized rhizosphere microbiome was transplanted to mitigate salinity stress in chilli and bell pepper. RMT effectively increased various plant growth parameters in both plant model systems under salinity stress (150 mM in chilli and 170 mM in bell pepper). In RMT inoculated plants, there was a reduction in stress markers, viz. , malondialdehyde and proline levels. Further, the K + /Na + ratio increased by 1.94- to 3.47- fold in plants with RMT + salt stress. In addition, the expression level of salt stress-responsive gene, SlHKT1;1 , increased in RMT plants under salt stress in both chilli and bell pepper compared to only salt-treated plants. Our study showed that previously salt stress-acclimatized tomato RMT is an effective and sustainable strategy to enhance salinity tolerance in other plants under natural conditions. • Rhizosphere microbiome transplantation (RMT) performed under natural conditions. • Tomato rhizosphere transplanted in chill and bell pepper • Biochemical stress factors were reduced in RMT+salt treated plants. • Upregulation of SlHKT1;1 after RMT inoculation in chilli and bell pepper. • The efficacy of RMT was more prominent in chilli compared to bell pepper.