Poster: Secondary Metabolism

Abs # 290: A gene responsible for colour variegation in flowering peach

Presenter:	Uematsu, Chiyomi , uematsu@lyra.vega.or.jp
Authors	Uematsu, Chiyomi  (A)   Katayama, Hironori  (B)   Arakawa, Osamu  (C)   Martin, Cathie  (D)
Affiliations:	(A): Botanical Gardens, Graduate School of Science, Osaka City University (B): Experimental Farm, Faculty of Agriculture, Kobe University (C): Faculty of Agriculture and Life Science, Hirosaki University (D): Department of Cell and Developmental Biology, John Innes Centre

A gene encoding a MYB-like transcription factor structurally similar to proteins controlling anthocyanin synthesis in other species was isolated from flowering peach. It is known that some peach trees bear pink flowers (PFs) and variegated flowers (VFs) within one tree. Although this phenotype is probably caused by the activity of a transposon, transposable elements have not yet been isolated from woody species. HPLC analysis indicated that cyanidin-3-glucoside was the major pigment in PFs. VFs contained only 1 to 7 % compare to PFs. The expression of chalcone synthase (CHS), dihydroflavonol 4-reductase (DFR) and anthocyanidin synthase (AS) was investigated by RT-PCR using RNA extracted from pink flower buds (PFBs) and variegated ones (VFBs). The CHS gene was expressed both in PFBs and VFBs. The DFR gene and the AS gene were expressed only in PFBs. These results suggested that the variegated phenotype involved mutation of a gene encoding a transcription factor regulating the latter part of the anthocyanin biosynthesis pathway. Complementation of pigment synthesis in white sectors was examined using five genes encoding transcription factors from Antirrhinum majus; Rosea1, Rosea2, Venosa, Mutabilis and Delila. These genes were used for transient expression by means of particle bombardment. Only Rosea1 could restore pigment synthesis. To isolate the gene functionally homologous to Rosea1 from flowering peach, RT-PCR cloning and 5'RACE were performed using oligonucleotides based on the Rosea1 sequence. A full length of cDNA encoding a MYB-like transcription factor was obtained from PFBs. This gene was expressed in PFBs but expression was not detected in VFBs, so this gene is a good candidate for the one responsible for colour variegation.