Articles
INDUCTION OF HAPLOID PLANTS IN POLISH ONION CULTIVARS
The process of gynogenesis was conducted on media described by Campion, et al. (1990, 1992).
The buds were taken from two Polish cultivars (‘Wolska’ and ‘Kutnowska’), grown in a greenhouse (bulbs potted on January 5, buds collected in May and June), and from three cultivars (‘Wolska’, ‘Czerniakowska’ and ‘Rawska’) grown in a field (bulbs planted in April, buds collected in August). Nine combinations of media, three different temperature conditions and buds of different sizes were used for the cultures.
Cultivar ‘Wolska’ grown in a greenhouse gaves an average of 2.2 embryos per 100 buds, but only 0.26 % of developing embryos if it was gown in a field.
Around 2000 buds were cultured in both combinations.
The yield of embryos obtained by gynogenesis from cv. ‘Kutnowska’ grown in a greenhouse was very close to that from ‘Wolska’. Among cultivars grown in a field, ‘Rawska’ produced the highest number of embryos.
The A1 medium, followed by F6 or B regeneration media after 14 days of culture, was the most useful for the induction of embryos from donor plants grown in a greenhouse.
However, the F6 medium followed by a transfer to another F6 or B media showed to be the best for buds from plants grown in a field.
Only 52 % of embryos or young plantlets plated on the multiplication medium continued their growth, forming adventitious shoots, which were subsequently rooted.
Around 60 % of young plants survived the adaptation to in vivo conditions.
The evaluation of the ploidy level of the obtained plants by counting the chromosome number in root tip cells, collected while plants were being moved from in vitro culture to the soil, revealed that 58 % of them were diploid, 33 % were haploid and 9% were polyploid.