CDNA-AFLP analysis on 2 Osmanthus fragrans cultivars with different flower color and molecular characteristics of OfMYB1 gene

Abstract

In this study, we carried out cDNA-AFLP analysis on petals of 2 Osmanthus fragrans cultivars, yielding 102 cDNA fragments. OfMYB1 gene was cloned and the molecular characteristics were studied. The Osmanthus fragrans cultivars ‘Dangui’ and ‘Yingui’ differ considerably in floral coloration and volatiles. We carried out cDNA-AFLP analysis on petals of the two cultivars to isolate genes involved in the production of floral pigments and aromatic chemicals. Using 256 primer combinations, we detected 390 differentially expressed fragments, yielding 102 cDNA fragments. Of the differentially expressed transcripts, 45 were upregulated in ‘Yingui’ and 57 were upregulated in ‘Dangui’. The differentially expressed genes were involved in several metabolic and signal transduction pathways. According to the cDNA-AFLP analysis, a 72-bp fragment was upregulated in ‘Dangui’, sequence comparison of the differentially expressed transcript-derived fragment showed this to be a MYB transcription factor. The cDNA of OfMYB1 was 749 bp long and contained a coding sequence of 585 bp encoding a polypeptide of 195 amino acids. A phylogenetic analysis placed the OfMYB1 gene within the subgroup containing “nyWsV/M E/DDlWP/S” motif. Protoplast transformation experiment showed that OfMYB1 protein accumulated in cell nuclei. Yeast one hybrid assay confirmed that OfMYB1 acted as a transcriptional activator to regulate expression of OfPAL gene. The differential expression patterns of OfMYB1 and anthocyanin biosynthetic pathway genes (OfCHS, OfCHI, OfDFR and OfANS) in the 2 O. fragrans cultivars suggested that OfMYB1 may not regulate the expression of these genes.