Improving plant salt tolerance using the endophytic halophile Vreelandella salis sp. nov.

Soil salinity is a pervasive abiotic stress that severely constrains global crop productivity, demanding sustainable biotechnological solutions. This study characterized Vreelandella salis strain PAMB 3232ᵀ, a novel species of halophilic endophytic bacterium isolated from the shoot of the halophyte Suaeda maritima. Polyphasic analyses confirmed the taxonomic delineation of PAMB 3232ᵀ. This strain exhibits remarkable halotolerance, sustaining growth in up to 24% (w/v) NaCl. Genomic analysis revealed an enrichment of genes associated with metabolic resilience, particularly those involved in carbohydrate and amino acid metabolism, as well as cofactor and vitamin biosynthesis. Inoculation with strain PAMB 3232ᵀ significantly enhanced growth in Brassica rapa, increasing the shoot fresh weight by 26% under non-saline conditions and by 17.0% under salinity stress (200 mM NaCl). Physiological analyses further indicated enhanced stress tolerance, reflected by improved K+/Na+ homeostasis and reduced malondialdehyde (MDA) accumulation. Moreover, rhizosphere microbiome profiling revealed that inoculation reshaped the rhizosphere microbial community. Under salinity, the rhizosphere network showed increased connectivity and modularity, with Pseudomonadota serving as key hubs and enrichment of beneficial Bacillota. Collectively, these results indicate that V. salis PAMB 3232ᵀ enhances crop salt tolerance via coordinated physiological and microbiome-mediated effects, supporting its potential as a microbial inoculant for salt-affected agriculture.