Ectopic expression of SpABR1 positively regulates drought stress tolerance through the ABA-dependent pathway and by promoting ROS scavenging in Arabidopsis

Abstract

Glucosyltransferases, Rab-like GTPase activators and Myotubularins (GRAM) domain-containing proteins are essential for plant growth and reactions to abiotic stresses. The desert shrub willow Salix psammophila C. is native to arid and semi-arid areas and has strong tolerance of abiotic stresses. We previously identified a GRAM domain-containing protein, SpABR1, as a hub gene in the response of S. psammophila to drought stress. In this study, SpABR1 was isolated and functionally characterized. Analysis of expression patterns revealed highest SpABR1 expression in the roots. Additionally, GUS staining revealed the upregulation of SpABR1 in response to drought stress and ABA treatment. Overexpression of SpABR1 resulted in enhanced tolerance to drought stress and heightened ABA sensitivity. Compared to wild-type (WT) plants, plants with overexpressed SpABR1 exhibited increased activities of antioxidant enzymes under drought stress. In SpABR1 overexpression plants, there was higher expression of stress-related genes and ABA biosynthesis-related genes compared to WT plants under drought stress conditions. Additionally, results from a yeast one-hybrid screening assay and luciferase analysis revealed that SpNAC2 is an up-regulated gene that directly interacts with the promoter region of SpABR1 to activate its expression. Our findings revealed a positive role of SpABR1 in drought stress and provided insight into its regulatory network.