TITLE:
Transforming the Snapdragon Aurone Biosynthetic Genes into Petunia Alters Coloration Patterns in Transgenic Flowers
AUTHORS:
Chen-Kuen Wang, Yi-Chin Chin, Chih-Yu Lin, Po-Yen Chen, Kin-Ying To
KEYWORDS:
Agrobacterium-Mediated Transformation, Aurone, Compound Identification, Flower Color, Genetic Engineering, HPLC Profiling, Suppression, Transgene-Induced Gene Silencing
JOURNAL NAME:
Advances in Bioscience and Biotechnology,
Vol.6 No.12,
December
18,
2015
ABSTRACT: Aurones belong to a small class of flavonoids that provide yellow color in some floricultural plants
including snapdragon. To explore novel flower coloration, two full-length cDNAs encoding chalcone
4'-O-glucosyltransferase (designated as SRY4'CGT) and aureusidin synthase (designated as SRYAS1) in the aurone biosynthetic pathway were cloned from yellow flowers of snapdragon (Antirrhinum
majus cv. Ribbon Yellow). Binary vectors were constructed and transformed separately
into Petunia hybrida harboring blue flowers. Only a few flowers in 4 out of 9 transgenic SRY4'CGT plants showed variegated blue-white sectors; as time passed, amounts of variegated flowers and
proportion of white sectors in the background blue color of the new-born flowers gradually increased,
until finally, the petal color was completely white in all late-born flowers. In contrast, a
few flowers in 3 out of 13 transgenic SRYAS1 plants showed variegated blue-white sectors; but, the
amounts of variegated flowers did not increase over the whole flowering stage, and no complete
white flowers were observed. RNA samples isolated from blue and white sectors of T1 transgenic SRY4'CGT plants were analyzed by reverse transcription-PCR, transgenic SRY4'CGT transcripts
were detected in both sectors; however, transcripts of an upstream gene, chalcone synthase (CHS),
were abundantly detected in the blue sectors but largely reduced in the white sectors, suggesting
that the expression of CHS gene was suppressed in white sectors of transgenic plants. Furthermore,
HPLC coupled with mass spectrometry demonstrated cyandin, malvidin and their derivatives were
absent in white sectors, causing the white phenotype. Our findings may be attractive to molecular
breeders.