Harnessing the plant‑associated microbiome: Rhizosphere and endophyte plant growth‑promoting bacteria (PGPB) to mitigate salt stress in the Egyptian wheat

Salt stress poses a significant threat to wheat productivity, particularly in arid and semi-arid regions such as Egypt, where soil salinity severely limits crop yield and long-term agricultural sustainability. With increasing recognition of the plant-associated microbiome as a key component of crop resilience, this study investigated the potential of plant growth-promoting bacteria (PGPB) and plant–microbe interactions to alleviate salt-induced stress in two contrasting Egyptian wheat cultivars: the salt-tolerant Sakha 93 and the salt-sensitive Sids1. Bacterial isolates from both rhizospheric and endophytic niches were collected from saline-irrigated wheat and identified using 16S rRNA gene sequencing. Functional characterization identified Pseudomonas stutzeri and Pantoea agglomerans as promising PGPB candidates based on their ability to produce indole acetic acid, ACC deaminase, and siderophores, fix nitrogen, and tolerate high salinity. In greenhouse trials under salinity gradients (0–15 dS/m), both strains improved wheat growth metrics, though Pantoea agglomerans, particularly in Sakha 93, led to significant increases in biomass, root length, seed yield, and proline content. Pseudomonas stutzeri showed beneficial but comparatively moderate effects. These results suggest that endophytic PGPB, especially under saline conditions, may confer enhanced stress tolerance due to superior colonization and physiological modulation. The findings support the use of halotolerant microbial bioinoculants in combination with salt-tolerant genotypes as a viable strategy to enhance wheat resilience and productivity in saline environments.