THE EFFECT OF FLOWER BUD SIZE AND PRE-TREATMENT ON CALLUS INDUCTION AND PLANT REGENERATION IN ANTHER CULTURE OF PETUNIA 'PURPLE WAVE'
Usually anther culture is used for haploid production but it may also have potential for developing plants with various ploidy levels which can be used in plant breeding programmes. Flower buds of Petunia Purple Wave were distributed into 3 groups (4-6, 7-10 and 11-14 mm bud length) to investigate their morphogenetic competence. Five pre-treatments (cold 5±1°C, heat 33±1°C, starvation, cold with starvation and heat with starvation) were applied for 3, 5 and 8 days to 760 anthers. Anthers were cultured on an induction medium according to SANGWAN and NORREEL (1975) supplemented with 0.1 mg/L BA and 1 mg/L NAA, incubated for one month at 25°C in the dark and then transferred into the light. Callus development was observed after 2 weeks on the induction medium. After 2 months calli were transferred to MS-medium with 2 mg/L BA for shoot regeneration. Shoots were isolated and rooted on half-strength MS-medium. No difference regarding the morphogenetic competence of anthers in lengths between 4 and 10 mm was found. The results showed the necessity of pre-treatment to enhance callus formation rates. By the pre-treatments the number of callus forming anthers increased compared to the control (up to 35 vs. 10%). The duration of pre-treatment was optimal between three and five days. Callus formation was stimulated by heat and cold with starvation pre-treatments. However, most (56%) of all regenerated plants were obtained after cold pre-treatment. Finally, 39 plants were acclimatised and transferred into the greenhouse. The ploidy level of regenerated plants was determined indirectly by measuring stomata and pollen length. Thirty plants were diploid and 9 plants were tetraploid. Reasons for this high ratio of tetraploid plants will be investigated in further studies. The method described is a useful tool to generate tetraploids which are valuable in breeding programmes.
Chaar, M., Pinker, I., Grieger, P. and Böhme, M. (2012). THE EFFECT OF FLOWER BUD SIZE AND PRE-TREATMENT ON CALLUS INDUCTION AND PLANT REGENERATION IN ANTHER CULTURE OF PETUNIA 'PURPLE WAVE'. Acta Hortic. 961, 375-382
tetraploid Petunia, ploidy determination, microspore stage, cold, heat, starvation