Abstract: Tepals of Hyacinthus orientalis L. were used as explants to induce the formation of ovules through controlling the level of 6-BA and 2, 4-D in the media. Anatomical studies using light microscopy showed that the development of in vitro ovules resembled that of in planta. To investigate the temporal and spatial expression pattern of homads1 during in vitro ovule initiation, which is involved in the determination of ovule identities in Hyacinthus, RNA in situ hybridization was carried out. The hybridization signals were first detected in some cells along the edge of carpel-like organ, from which the ovules were derived, and then restricted to the ovule primordial and ovules. The results indicated that homads1 plays an important role in the initiation and development of in vitro ovules. Further expression analysis by RT-PCR indicated that homads1is induced by low level of 6-BA and 2, 4-D duringin vitro ovule initiation and development. This study may provide some clues to understand the molecular mechanism of ovule development regulated by hormones. 

Key words: Hyacinthus orientalis L., Ovule, Flower bud, Gene, Expression analysis, Plant growth regulator