ARS | Publication request: Anthocyanin regulatory/structural gene expression in Phalaenopsis

Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 13, 2008
Publication Date: January 21, 2009
Repository URL: http://hdl.handle.net/10113/28169
Citation: Ma, H., Pooler, M.R., Griesbach, R.J. 2009. Anthocyanin regulatory/structural gene expression in Phalaenopsis. Journal of the American Society for Horticultural Science. 134:88-96.

Interpretive Summary: Anthocyanins are plant pigments that contribute to red or purple coloration in leaves, flowers, and fruit. Anthocyanin biosynthesis involves the interaction of several families of regulatory factors including R-like MYC, R2R3-MYB, and WDR proteins. To determine the roles of these proteins in anthocyanin biosynthesis, we compared the expression of these proteins in orchid (Phalanenopsis) species that had either white (anthocyanin-free) or red (anthocyanin-containing) flowers. We found that regulatory gene Mybs showed similar expression levels in both species, but sequencing of randomly selected clones revealed that the anthocyanin-specific regulatory gene Mybs only appeared in the red-flowering species. Several full-length anthocyanin-related Mybs were isolated from the red-flowering orchid species and introduced into the white-flowering species to induce anthocyanin expression.

Technical Abstract: Partial cDNA fragments of Myb, Myc, Wd, Chs and Dfr genes were generated by Reverse Transcription-PCR using total RNA isolated from flowers of P. amabilis (L.) Blume (anthocyanin-free) and P. schilleriana Rchb. f. (anthocyanin-containing) and cloned into a TOPO vector. RT-PCR revealed that the structural gene Dfr was expressed at significantly higher level in P. schilleriana, as compared with P. amabilis. Regulatory gene Mybs showed similar expression levels, but sequencing of randomly selected clones of the expected insert size revealed that the anthocyanin-specific regulatory gene Mybs only appeared in P. schilleriana. Several full-length anthocyanin-related Mybs, with and without 5UTR, were isolated from P. schilleriana, and several were made into expression constructs and transiently expressed in P. amabilis to induce anthocyanin expression.