Heterologous expression of wheat TaRUB1 gene enhances disease resistance in Arabidopsis thaliana.

KEY MESSAGE: Expression of TaRUB1 gene in Arabidopsis thaliana elevates the level of disease-related genes in response to pathogen invasion through the accumulation of callose, necrotic cells, and the outbreak of ROS. Ubiquitin (Ub) and ubiquitin-like proteins are highly conserved in sequence and can covalently bind and modify many intracellular proteins which can be recognized and degraded by 26S proteasome. Post-translational modification of proteins has become a hot research spot today. In the previous study, a cDNA of related-to-ubiquitin protein belonged to ubiquitin-like proteins, whose spatial structure comprised Ub and NEDD8, was obtained from wheat SN6306 by suppression-subtractive hybridization and was named TaRUB1. TaRUB1 is induced by wheat powdery mildew and significantly upregulated in resistant wheat SN6306. In this study, heterologous expression of TaRUB1 in A. thaliana was used to study the function of this gene in response to pathogen Pseudomonas syringae pv. Tomato DC3000 (Pst DC3000). Transgenic A. thaliana showed relatively fewer disease symptoms, accompanied by common inhibition of living body parasitic defense responses, accumulation of more callose and reactive oxygen species (ROS), and concentrated cell death, simultaneously antioxidant enzyme activities of superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase were higher than those in wild-type (WT) plant after infection with Pst DC3000. Meanwhile, hypersensitive cell death, which was possibly ROS burst, was also observed in transgenic A. thaliana. By quantitative reverse transcription-polymerase chain reaction analysis, some marker genes for hypersensitive response showed significantly higher transcriptional expression level in transgenic A. thaliana, which activates system-acquired resistance, than that of WT plants. Heterologous expression of TaRUB1 can significantly enhance resistance to Pst DC3000 in A. thaliana, suggesting that TaRUB1 is related to plant disease resistance.