Heterologous Expression of Arabidopsis rty Enhances Drought Tolerance in Strawberry (Fragaria × ananassa Duch.)

Abstract

Background Strawberry ( Fragaria × ananassa Duch.) is an important fruit crop worldwide. It was particularly sensitive to drought stress because of their fibrous and shallow root systems. Mutation of Arabidopsis thaliana ROOTY ( RTY ) results in increased endogenous auxin levels and roots and shoot growth, but the effects of this gene in strawberry remain unclear. Results Here, we heterologously expressed Arabidopsis rty in strawberry plants and examined the effects of rty expression on the hormonal and physiological properties of the plants. Heterologous expression of rty induced IAA accumulation and increased the production of adventitious roots as well as trichomes on the abaxial leaf surface of the transgenic plants. Furthermore, the transgenic strawberry plants had increased ABA accumulation and stomatal closure. The transgenic strawberry plants exhibited enhanced water use efficiency and a reduced water loss rate. Additionally, peroxidase and catalase activities were significantly higher in the transgenic plants than in the untransformed controls, and the transgenic plants were more drought tolerant than the wild-type plants. Our results uncover a transgenic approaches can be used to overcome the inherent trade-off between plant growth and drought tolerance by enhancing water use efficiency and reducing water loss rate under water shortage conditions. Conclusions In this study, the rty gene improves hormone-mediated drought tolerance in transgenic strawberry. We demonstrated that the heterologous expression of rty in strawberry improved drought tolerance by promoting auxin and ABA accumulation. These phytohormones together brought about various physiological changes that improved drought tolerance via increased root production, trichome density, and stomatal closure. This study provides the basis for future genetic modifications of strawberry to improve drought tolerance.