The Genetic Basis of Flower Color Differences in Nicotiana tabacum

Abstract

Nicotiana tabacum L accessions vary in flower color from light pink to magenta. The differences in flower color are attributable to differences in anthocyanin content. To determine the genetic basis of flower color differences, we generated transcriptomes and quantified transcript levels of flavonoid biosynthetic genes in four N. tabacum accessions and their diploid progenitors. High expression ratios of the flavonol synthase (FLS) gene to dihydroflavonol 4-reductase (DFR) gene are found in light-pink flowers, suggesting that competition between the FLS and DFR enzymes for the same substrates may drive the flux of the flavonoid biosynthetic pathway toward producing flavonols at the expense of anthocyanins, resulting in light-pink flowers. The high FLS:DFR expression ratio appears to be attributable to DFR activation later in development in light-pink flowers.