Maternal haploids of Petunia axillaris (Lam.) B.S.P. via culture of placenta attached ovules.

Hybridization of Petunia axillaris and P. parodii with Nicotiana tabacum was attempted using the method of in vitro pollination and fertilization. Seedlings were produced when the Petunia species and N. tabacum were used as the maternal parents; however, most of these had the identical somatic chromosome complement of the maternal parent. With crosses involving P. axillaris as the maternal parent, a low frequency of haploids was also produced. Due to the potential of haploids in basic and applied genetic research, additional experiments were carried out to determine whether in vitro pollination was necessary to stimulate haploid production and to more closely define the optimal time for ovule excision and culture. Four treatments were applied to accomplish these objectives. They were: placentas cultured prior to the time of anthesis, with and without pollination, and placentas cultured after the time of anthesis, with and without pollination. In vitro pollination had no effect on the frequency of haploids produced. Placenta attached ovules cultured prior to the time of anthesis produced significantly more haploids than those cultured after anthesis. The preanthesis treatment produced a frequency of 6.5 haploids per 100 ovaries cultured. The culture of placenta attached ovules provides an alternative to anther culture as a means for haploid production.