Nucleus substitution between Petunia species using gamma ray-induced androgenesis.

The ovaries of two different Petunia species: Petunia hybrida (hort) and Petunia parodii (Steere) were irradiated with τ-ray doses ranging from 50 to 1,000 Gy before pollination. Seed setting occurred after 4 days preculture on a non-sterile medium. Ovaries transformed into fruits were then cultivated aseptically with the following results: (1) τ-ray doses ranging from 200 to 1,000 Gy led to the development of two types of plants: haploids 2n=x=7 and overdiploids 2n>2x=14. (2) The androgenetic origin of haploids was ascertained by using genetic markers. The origin of overdiploids is discussed. (3) Androgenetic haploids contained the chloroplasts of the irradiated female parent. No visible change of cp DNA patterns was observed after irradiation. (4) The four possible androgenetic events were successfully obtained between the two Petunia species: hybrida haploids with hybrida or parodii cytoplasm, and parodii haploids with parodii or hybrida cytoplasm.