Soil microbes’ role in plant germination and growth under salt stress

One significant consequence of climate change is the rising sea levels, which contribute to the intrusion of saltwater towards the inland and groundwater placing extreme salt stress on many plants. Beneficial interactions with microorganisms may be crucial for ameliorating salt stress and facilitating the ecosystem services plants provide. We aimed to test if microbes aid plants in coping with salinity stress and to identify potential applications for enhancing plant resilience in the face of ongoing environmental changes. We set up a factorial experiment that manipulated the introduction of field collected soil microbes, the salinity of these introduced microbes, and the salinity of the water in which plants were grown (freshwater vs. saltwater). To identify the impact of native microbes on the survival of plants in high stress environments, specifically we examined how a Liatris spicata, a freshwater plant would germinate and grow in salt environments. The overall germination of L. spicata showed that native microbes from high salinity sites positively affect the growth of plants in saltwater. Germination rate was significantly higher (25.8 %) in plants with microbes compared to control plants. Both saltwater exposure and microbial presence had a significant effect on plant growth, suggesting that the impact of saltwater on plant growth depends on the presence of microbes. Our results revealed a significant decrease in the number of microbial colony-forming units (CFUs) in response to saltwater treatment (p < 0.001). Both fungal and bacterial CFUs were significantly reduced in saltwater-treated soils compared to freshwater soils. These findings highlight the potential role of native soil microbes in enhancing plant resilience to salinity stress, offering valuable insights for improving plant survival and productivity in increasingly saline environments.