Coordinated regulation of biosynthetic and regulatory genes coincides with anthocyanin accumulation in developing eggplant fruit

Authors: Stommel, John; Dumm, Judith

Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2015
Publication Date: 4/17/2015
Citation: Stommel, J.R., Dumm, J.M. 2015. Coordinated regulation of biosynthetic and regulatory genes coincides with anthocyanin accumulation in developing eggplant fruit. Journal of the American Society for Horticultural Science. 140:129-135.

Interpretive Summary: Eggplant fruit color varies from white to green through varying shades of violet to black. Relatively little is known concerning the genes responsible for these varied fruit colors. We evaluated the activity of genes involved in production of violet eggplant fruit pigments. High levels of gene activity resulted in accumulation of violet pigments and violet to black fruit color. Conversely, low levels of gene activity resulted in low levels of violet pigments and white to green fruit color. This information on eggplant fruit color will be useful to scientists studying biosynthetic pathways responsible for production of plant pigments and facilitate development of novel pigmented eggplant varieties.

Technical Abstract: Violet to black pigmentation of eggplant (Solanum melongena) fruit is attributed to anthocyanin accumulation. Model systems support the interaction of biosynthetic and regulatory genes for anthocyanin biosynthesis. Anthocyanin structural gene transcription requires the expression of at least one member of each of three transcription factor families - MYC, MYB and WD40. In order to determine the genetic basis for anthocyanin pigmentation in eggplant fruit, we utilized real-time PCR to evaluate the expression of anthocyanin biosynthetic (Chs, Dfr, Ans) and regulatory (Myc, Myb, Wd) genes in S. melongena genotypes that produce fruit with dark violet or white coloration, respectively. Gene expression and anthocyanin content was evaluated in fruit at various stages of development ranging from small post-anthesis fruit to full-size marketable fruit. Anthocyanin content increased 10-fold in developing violet colored fruit, with average levels nearly 500-fold greater than those measured in white fruit. Coincident with anthocyanin content, biosynthetic gene transcript levels were significantly higher in violet tissue than in white tissue with greatest differences observed for Ans transcript levels. Myb and Myc transcript levels were also higher in violet pigmented tissue in developing fruit with Myc levels exhibiting much greater fold increases that closely mirrored anthocyanin levels in developing fruit. No differences were observed in expression of the Wd gene.