ISHS Acta Horticulturae 560: IV International Symposium on In Vitro Culture and Horticultural Breeding
INDUCTION OF TETRAPLOIDS FOR BREEDING HARDY ORNAMENTALS |
| Authors: | J.B. Rose, J. Kubba, K.R. Tobutt |
| Keywords: | colchicine, flow cytometry, tetraploidy, in vitro, Buddleia, Syringa, Sorbus |
| Abstract:
The induction of tetraploids has three main uses for the East Malling breeding programme: to equalise ploidy prior to crossing two taxa of unequal ploidy; to restore fertility of sterile interspecific hybrids; and to produce changes in organ size and plant habit. Traditionally induction of tetraploidy using colchicine was done in vivo but more recently in vitro techniques have been developed. We have combined the application of colchicine to nodal explants in vitro with the use of flow cytometry to develop tetraploids in three genera. Tetraploid plants of Buddleia globosa, which is naturally a diploid, were produced, and have been crossed with the natural tetraploid B. davidii ‘Nanhoensis Alba’, to introgress yellow flower colour into B. davidii. Tetraploids were produced of two sterile hybrids of Syringa vulgaris x S. pinnatifolia. If fertile they will allow further rounds of crossing to be made, to combine the flower size of the former with the pinnate leaves of the latter. Tetraploids of Sorbus aucuparia ‘Biessneri’ have been produced which we hope will prove more dwarfing than the original diploid, and, when used as a rootstock, will allow some of the other ornamental but vigorous Sorbus cultivars to be grown in small gardens. The in vitro application of colchicine to nodal explants enabled the rapid development of tetraploids in these three genera and could be applied to others. | |
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