Identification and expression analysis of a MYB family transcription factor in the parasitic plant Orobanche ramosa

MYB proteins are transcription factors (TFs) involved in the regulation of developmental processes in eukaryotes. A number of MYB genes have been identified from plants, but they have not been studied in parasitic plants. In this work, a member of the R2R3 MYB family of TFs was isolated from a complementary DNA library representing different developmental stages of the parasitic plant Orobanche ramosa. The pattern of expression of the gene was studied by in situ hybridisation. Alignment of the deduced Or-MYB1 protein with members of the MYB family showed the highest overall identity with MYB.Ph3 from petunia ( Petunia hybrida), NtMYBAS1/S2 from tobacco ( Nicotiana tabacum) and AtMYB101 from Arabidopsis thaliana. Amino acid sequence comparisons of DNA-binding domains showed that Or-MYB1 protein forms a closely related group with these proteins. Transcripts of Or-MYB1 were detected during all the developmental stages analysed, and in situ hybridisation showed that the expression was restricted to the parenchymatic cells proximal to the vascular vessels. These findings are consistent with a role of Or-MYB1 during early stages of development of O. ramosa, probably through the phenylpropanoid pathway.