Halophyte-associated salt-tolerant rhizobacteria: ecological adaptation, mechanistic pathways, and translational relevance for wheat salinity tolerance

Csengele Barta, Beatrice Kelemen, Stan Svojanovsky, Phoenix Ariel Schlorff, Gyongyi Szekely

Background
Soil salinization is an expanding constraint to agricultural productivity worldwide, particularly in irrigated and arid regions and strongly limits wheat growth and yield. Although breeding and biotechnology have produced cultivars with improved ion-exclusion and tissue-level tolerance, these advances alone do not fully mitigate salinity-induced disruptions in rhizosphere processes and microbial activity. Salt-tolerant plant growth-promoting rhizobacteria (ST-PGPR) represent a complementary biological strategy and halophyte-derived strains are increasingly explored due to their pre-adaptation to saline environments. However, the influence of ecological origin on functional relevance and field performance remains poorly understood. This review synthesizes existing evidence on ST-PGPR effects in salinity-affected wheat with emphasis on inoculant origin.
Scope
We critically reviewed controlled-environment and field studies evaluating salt-tolerant PGPR in wheat under salinity stress. We compared the use of halophyte-derived versus non-halophyte-derived strains, summarized mechanistic contributions to nutrient acquisition, ion homeostasis, osmotic adjustment and oxidative stress mitigation and evaluated how these mechanisms translate into field-level yield responses. We also identified gaps in field validation and experimental design. Controlled studies consistently demonstrate physiological benefits of ST-PGPR, including improved germination, biomass, antioxidant capacity and stress resilience, although responses vary with wheat genotype and salinity intensity. Field evidence, however, remains limited, fragmented and mostly based on strains from non-saline soils, with inconsistent yield outcomes and few multi-season trials.
Conclusion
Halophyte-derived ST-PGPR represent a promising yet underexplored biological resource for saline agroecosystems. Translational success will require multi-site, multi-year field validation, assessment of persistence and ecologically-informed inoculant design to bridge controlled efficacy and reliable agronomic performance.