Interspecific crosses of lily by in vitro pollinated ovules.

Abstract. Because of pre-and post-fertilization barriers, successful interspecific crosses have not been reported for Liliurn using Asiatic hybrid as the mother to cross with Oriental or Lilium longiflorum. Using an in vitro ovular pollination method, where pollen tubes directly penetrate isolated ovules, this study demonstrated that 1) the Brewbaker and Kwack agar plate containing sucrose (10%), with the isolated ovules being placed ca. 1mm apart from the pollen, is optimal for pollination, 2) interspecific crossing barriers do not occur during penetration of the pollen tubes into the micropyle. 3 micropylar penetration can be obtained in all kinds of intra- and inter-specific cross combinations of lily cultivars, 4) multiple penetration occurs, in which the penetrating pollen tubes pass the embryo sac without entering the synergid cells, 5) a small amount of pollen tube penetrates the synergid cells in the A x 0 cross, and 6) completion of pollen tube penetration (8-12 h after germination) is much earlier than the division of the generative cell in sperm cells (17 h after germination), which may be the primary cause for the failure in fertilization.