Transcriptional regulation of enzymes involved in ROS metabolism and abiotic stress resistance in rolC- transformed cell cultures

The rolC (root locus C ) gene from Agrobacterium rhizogenes belongs to the family of plast oncogenes causing significant changes in plant growth and morphology. The overexpression of the rolC provokes the suppression of reactive oxygen species (ROS) generation and reinforces stress tolerance in transgenic cells. In this study, we tested whether this effect is associated with changes in the expression of oxidative and antioxidative enzymes such as NADPH oxidase (termed respiratory burst oxidase homologs; RBOH), superoxide dismutase, catalase, and ascorbate peroxidase. The expression of genes, encoding RcRBOHs and AtRBOHs, the major producers of ROS, was two times lower in both Rubia cordifolia and Arabidopsis thaliana rolС -expressing cultures. Temperature and salt stresses induced expression of Rboh genes, yet this effect was significantly less evident in transgenic calli. The mRNA transcript abundance of most of the antioxidant genes was strongly inhibited in rolC -expressing cultures under normal conditions. However, expression levels of antioxidant enzymes were 1.5 times higher in transgenic calli compared to the control under tested abiotic stresses. Our results indicate that RolC specifically regulates NADPH oxidase and antioxidant genes expression to suppress ROS production. In summary, these effects result in an increased tolerance of rolC -expressing cells to abiotic stress conditions.