Characterization of RsMYB28 and RsMYB29 transcription factor genes in radish (Raphanus sativus L.).

Glucosinolates (GSLs) are important secondary metabolites in Brassicaceae plants. Previous studies have mainly focused on GSL contents, types, and biosynthesis-related genes, but the molecular characterization patterns of GSL biosynthesis-related transcription factors remain largely unexplored in radish (Raphanus sativus L.). To isolate transcription factor genes regulating the GSL biosynthesis, genomic DNA and cDNA sequences of RsMYB28 and RsMYB29 genes were isolated in radish. Two R2R3-MYB domains were identified in the deduced amino acid sequences. Subcellular localization and yeast-one hybrid assays indicated that both the RsMYB28 and RsMYB29 genes were located in the nucleus and possessed transactivation activity. Reverse transcription quantitative analysis showed that the RsMYB28 and RsMYB29 genes were expressed in seeds, leaves, stems, and roots at the seedling, taproot thickening, and mature stages. Both genes were highly expressed during the seedling and taproot thickening stages. The expression level of RsMYB28 was found to be up-regulated following wounding, glucose, and abscisic acid treatments, whereas RsMYB29 was up-regulated following wounding and methyl jasmonate treatments. These results provide insights into the biological function and characterization of the RsMYB28 and RsMYB29 genes, and facilitate further dissection of the molecular regulatory mechanism underlying the GSL biosynthesis in radish.