Yellow pinks: interspecific hybridization between Dianthus plumarius and related species with yellow flowers

Interspecific hybridization was carried out with the aim of transferring yellow flower colour from yellow-flowered carnations (2n=2x=30) and Dianthus knappii (2n=2x=30) to a white-flowered cultivar of the garden pink, Dianthus plumarius (2n=6x=90). These hybrids were difficult to make but a small number were produced from both cross combinations. All the progeny from the crosses with carnations were pink but those from crosses with D. knappii were pale cream-yellow, with some variation in intensity between plants. Differences were observed in chromosome number between hybrids, which were either tetraploid, which is the expected situation, or pentaploid. Observations on pollen mother cell meiosis and pollen production in D. knappii revealed that the plants were producing unreduced (diploid) gametes at significant frequencies. Analysis of the flower pigments showed that the yellow flower colour of D. knappii resulted from the presence of high levels of flavone and flavonol glycosides whereas those of yellow carnations were chalcones. Thus, the Fl hybrids with D. knappii were yellow because they contained the same pigments as D. knappii but the hybrids with the carnations were pink due to their ability to convert chalcones through to dihydroflavones and then to anthocyanins. (C) 1998 Elsevier Science B.V. All rights reserved.