Effect of cytokinins on expression of radish CLE genes

CLE (CLAVATA3/ENDOSPERM SURROUNDING REGION) peptides are peptide phytohormones playing the important role in the regulation of various type meristem development and also in the interaction between plants and parasites and symbionts. At the same time, the interaction of CLE peptides with other phytohormones, participating in these processes, is essentially unstudied. Using real-time RT-PCR, we analyzed expression of some genes encoding CLE peptides in radish (Raphanus sativus var. radicula Pers.) under normal conditions and after treatment with the cytokinin 6-benzyladenine. Even after short-term (30 min) action of cytokinin, expression of group A CLE genes was manifold suppressed, whereas cytokinin did not affect expression of group B CLE genes. Radish lines contrasting in the trait “spontaneous tumor formation” demonstrated similar dynamics of CLE gene expression in response to cytokinin treatment but differed in the levels of their expression. A possibility of interaction between CLE peptides and cytokinins in the spontaneous development of tumors in radish lines is discussed. The important part of the work was the selection of optimal reference genes for the analysis of radish gene expression by real-time RT-PCR method. Most stable expression was observed for the genes of ubiquitin (RsUBQ) and glyceraldehydes-3-phosphate dehydrogenase (RsGAPDH).