The 2012 ASHS Annual Conference

Eggplant, Solanum melongena, fruit color is an important determinant of fresh product quality.  Marketable fruit color varies from white to green through varying shades of violet to black.  The genes responsible for the biosynthesis of anthocyanin compounds in eggplant that contribute to fruit color are not well characterized.  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.  These transcription factors form a complex that binds to structural gene promoters, thereby modulating gene expression.   In order to determine the genetic basis for tissue 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 dark violet pigmented and white non-pigmented fruit.  Gene expression was evaluated in fruit from respective genotypes at various stages of development ranging from small post-anthesis fruit to full-size marketable fruit.  Biosynthetic gene transcript levels were significantly higher in anthocyanin pigmented tissue than in non-pigmented tissue with greatest differences observed for Ans transcript levels.  Myb and Myc transcript levels were also higher in anthocyanin pigmented tissue in developing fruit with Myc levels exhibiting much greater fold increases in comparison to those observed for Myb.  No differences were observed in expression of the Wd gene between anthocyanin pigmented and non-pigmented fruit.  Differences observed in gene expression for eggplant versus related Solanaceous species will be discussed.  The results are important for elucidating the genetic control of pigment biosynthesis and development of new plants with enhanced fruit quality and nutritive value.