Embryo-rescue in the genus Tulipa L.; successful direct transfer of T. kaufmanniana Regel germplasm into T. gesneriana L.

Summary Embryo-rescue was studied as a means to overcome post-fertilization barriers in interspecific crosses in the genus Tulipa. With compatible T. gesneriana L. cultivar crosses, ovule culture was found to be superior to isolated embryo culture. Complete plantlet formation was possible from an embryo size of about 0.5 mm onwards.In the interspecific cross T. gesneriana x T. kaufmanniana, which is hampered by embryo breakdown, successful rescue of abortive embryos was demonstrated. Optimal embryo-rescue was achieved in cultures started seven to nine weeks after pollination. With cultures initiated at a later time, the rate of success decreased. A low number of germinative seeds were obtained after normal ripening of the seed pods, but by using ovule culture the efficiency of seedling formation could be increased dramatically.The ovule culture procedure will allow novel crosses and will offer new possibilities for the introduction of desirable genes into tulip cultivars.