Modulation of NADPH-oxidase gene expression in rolB-transformed calli of Arabidopsis thaliana and Rubia cordifolia

• Full-length Rboh genes from Rubia cordifolia were identified.
• The RcRboh1 gene was regulated by temperature stresses, but not by NaCl or MeJA.
• The RcRboh3 gene represents stable isoform of R. cordifolia NADPH oxidase.
• The rolB gene induced the expression of both stress-inducible and stable Rboh genes.

Expression of rol genes from Agrobacterium rhizogenes induces reprogramming of transformed plant cells and provokes pleiotropic effects on primary and secondary metabolism. We have previously established that the rolB and rolC genes impair reactive oxygen species (ROS) generation in transformed cells of Rubia cordifolia and Arabidopsis thaliana. In the present investigation, we tested whether this effect is associated with changes in the expression levels of NADPH oxidases, which are considered to be the primary source of ROS during plant–microbe interactions. We identified two full-length NADPH oxidase genes from R. cordifolia and examined their expression in non-transformed and rolB-transformed calli. In addition, we examined the expression of their homologous genes from A. thaliana in non-transformed and rolB-expressing cells. The expression of Rboh isoforms was 3- to 7-fold higher in both R. cordifolia and A. thaliana rolB-transformed cells compared with non-transformed cells. Our results for the first time show that Agrobacterium rolB gene regulates particular NADPH oxidase isoforms.