Molecular cloning and characterization of seven class III peroxidases induced by overexpression of the agrobacterial rolB gene in Rubia cordifolia transgenic callus cultures.

Here, seven new class III peroxidase genes of Rubia cordifolia L., RcPrx01-RcPrx07, were isolated and characterized. Expression of the Prx genes was studied in R. cordifolia aerial organs as well as in cells transformed with the rolB and rolC genes of Agrobacterium rhizogenes and cells transformed with the wild-type A. rhizogenes A4 strain. In rolC- and rolB-transformed cells, the rol genes were expressed under the control of the 35S promoter, whereas in A. rhizogenes A4-transformed cells the rol genes were expressed under the control of their native promoters. All studied peroxidase genes were greatly upregulated in rolB-overexpressing cells. In contrast, overexpression of the rolC gene and expression of the rol genes under the control of their native promoters had little effect on the abundance of peroxidase transcripts. In accordance with this observation, peroxidase activity was substantially increased in rolB cells and was slightly affected in other transformed cells. Our results indicate that rolB strictly affects the regulation of a set of seven R. cordifolia class III peroxidases.