Adverse effect of urease on salt stress during seed germination in Arabidopsis thaliana

• Loss of function of AtUrease enhances salt tolerance during seed germination.
• Inhibiting urease activity improved the salt stress tolerance of WT seeds.
• The urease inhibitor significantly decreased the NH4+ level in WT seeds.

Seed germination is a critical stage in the development of crops that grow in saline soils. We noticed that seeds of an Arabidopsis urease mutant have significantly increased salt stress tolerance. To understand why, we treated the wild type (WT) with a urease inhibitor and found that its salt stress tolerance was also improved. We hypothesized that urease acting on urea generates NH4+, which probably exacerbates salt stress. As expected, the urease inhibitor significantly decreased the NH4+ level in WT seeds. These findings suggest that blocking urease activity improves salt tolerance during seed germination by lowering the concentration of NH4+.