Harnessing haloarchaea from halophyte Atriplex nummularia rhizosphere to enhance salt stress tolerance in maize seedlings

Abstract Soil salinization is a critical global issue threatening agricultural productivity and significantly reducing the availability of arable land. Effective mitigation and recovery strategies are vital for sustaining food production, especially in the context of climate change. Halophytic plants, such as Atriplex nummularia, have shown potential for remediating saline soils, though their large-scale application remains limited. An alternative approach involves leveraging microorganisms adapted to saline environments to enhance plant stress tolerance. In this study, we investigated the microbiome of A. nummularia under saline and non-saline irrigation conditions to identify extremophilic microorganisms that promote salt stress tolerance. Through 16S rRNA analysis, we identified members of the genus Haladaptatus exclusively in the rhizosphere of salt-irrigated plants. These microorganisms were isolated and inoculated into maize crop systems to evaluate their ability to confer salt tolerance. Our results demonstrate that Haladaptatus strains significantly enhance salinity tolerance in maize, with a marked increase in the relative abundance of archaeal 16S rRNA in soils as NaCl irrigation levels rise. This study provides the first evidence that Haladaptatus, an archaeon isolated from the rhizosphere of a halophyte, can significantly enhance salt tolerance in an agriculturally important crop. These findings suggest a promising biotechnological application for improving crop resilience in saline environments, offering a sustainable strategy for addressing soil salinization and securing food production in the context of global climate challenges.