A tomato ERF transcription factor, SlERF84, confers enhanced tolerance to drought and salt stress but negatively regulates immunity against Pseudomonas syringae pv. tomato DC3000

ERF proteins are plant-specific transcription factors that play significant roles in plant defense against various stresses. However, only little information regarding stress-related ERF genes is available in tomato (Solanum lycopersicum, Sl). In this study, a tomato ERF gene, SlERF84, was cloned and functionally characterized. The nucleus localization of SlERF84-sGFP was confirmed through a transient expression assay. Transactivation assays in yeast demonstrated that SlERF84 functions as a transcriptional activator. Real-time PCR analysis revealed that SlERF84 could be markedly induced by drought, salt and by several phytohormones (ABA, MeJA and ACC). Overexpression of SlERF84 in Arabidopsis endows transgenic plants with ABA hypersensitivity and enhanced tolerance to drought and salt stress. Histochemical staining assay showed that SlERF84 renders transgenic plants better ROS-scavenging capability. Pathogen inoculation assay revealed that SlERF84 might negatively modulate plant defense response to Pseudomonas syringae pv. tomato DC3000. Moreover, the transcript levels of pathogenesis-related genes AtPR1 and AtPR3 were compromised in transgenic Arabidopsis, as compared to that in Col-0 plants when inoculated with Pseudomonas syringae pv. tomato DC3000. These results suggest that SlERF84 functions as a stress-responsive transcription factor in differentially modulation of abiotic and biotic stress tolerance, and may have applications in the engineering of economically important crops.