Overexpression of AtOxR gene improves abiotic stresses tolerance and vitamin C content in Arabidopsis thaliana.

BACKGROUND: Abiotic stresses are serious threats to plant growth, productivity and result in crop loss worldwide, reducing average yields of most major crops. Although abiotic stresses might elicit different plant responses, most induce the accumulation of reactive oxygen species (ROS) in plant cells leads to oxidative damage. L-ascorbic acid (AsA, vitamin C) is known as an antioxidant and H2O2-scavenger that defends plants against abiotic stresses. In addition, vitamin C is also an important component of human nutrition that has to be obtained from different foods. Therefore, increasing the vitamin C content is important for improving abiotic stresses tolerance and nutrition quality in crops production. RESULTS: Here, we show that the expression of AtOxR gene is response to multiple abiotic stresses (salt, osmotic, metal ion, and H2O2 treatment) in both the leaves and roots of Arabidopsis. AtOxR protein was localized to the Endoplasmic Reticulum (ER) in yeast and Arabidopsis cells by co-localization analysis with ER specific dye. AtOxR-overexpressing transgenic Arabidopsis plants enhance the tolerance to abiotic stresses. Overexpression of AtOxR gene resulted in AsA accumulation and decreased H2O2 content in transgenic plants. CONCLUSIONS: In this study, our results show that AtOxR responds to multiple abiotic stresses. Overexpressing AtOxR improves tolerance to abiotic stresses and increase vitamin C content in Arabidopsis thaliana. AtOxR will be useful for the improvement of important crop plants through moleculer breeding.

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

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⁺.