The biochemistry and genetics of floral scent production as part of the petunia pollination syndrome

Floral scent plays a major role in flower discrimination by pollinators in the Petunia genus. By providing specific signals to pollinators, floral scent can significantly contribute to the plant pollination efficiency and reproductive success. Fragrant petunias mostly emit volatile benzenoids and phenylpropanoids from their petals, and time of emission coincides with foraging behavior of the preferred pollinators, thus making it an ideal model for investigating the role of scent as part of a pollination syndrome. Research on the biochemistry and genetics of petunia scent has developed intensively, with many biosynthetic steps being characterized and a draft petunia genome that is publicly available. In this thesis, we characterized a caffeoyl-CoA O-methyltransferase (CCoAOMT) from fragrant petals that leads to volatile phenylpropene production. We also demonstrated a link between CCoAOMT and anthocyanin production. Furthermore, we investigated the rhythmic volatile production in wild and cultivated petunia using recombinant inbred lines and promoter modification of the key regulator ODORANT1, respectively. Our results indicate that the timing of the expression of ODORANT1 determines the bouquet of volatiles produced.