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Badano wpływ jakości światła i ciemności na tempo regeneracji kalusa embriogennego Gymnocalycium mihanovichii (FRIČ ET GÜRKE) BRITTON ET ROSE f. aurantiaca in vitro. Stwierdzono, że przyrost kalusa na zmodyfikowanej pożywce MS bez regulatorów wzrostu był największy pod światłem żółtym oraz czerwonym. Największa zaś liczba kalusów zregenerowała struktury embrioidalne pod światłem żółtym, dziennym oraz czerwonym.
Astrophytum asterias (Zucc.) Lem. is a cactus which is among those most desired by producers and collectors all across the world and, at the same time, a species threatened with extinction in the natural environment. Micropropagation techniques can be helpful both in terms of its ex situ protection and its popularisation on the market, thus satisfying the needs of cacti breeders and collectors. Somatic embryogenesis is the most effective method of multiplication and it involves the formation of somatic embryos from vegetative cells. The medium, light conditions and type of explant demonstrate the key effect on its efficiency. Auxin 2,4-D (2,4-Dichlorophenoxyacetic acid) is most frequently applied to embryogenesis induction. In the present study we determined the effect of its concentration and light conditions on the efficiency of Astrophytum asterias somatic embryogenesis. Seeds were placed on the modified MS medium with a reduced content of macronutrients and sucrose ½MS (pH 5.7 – before autoclaving). All the in vitro cultures were incubated in the growth room (24 ± 2°C, 16 h light/8 h dark photoperiod, the intensity of quantum irradiation: 24.3 μmol·m⁻²·s⁻¹). After 14 days 70% of the seeds were produced of seedlings. To regenerate somatic embryos, halves of green seedlings were placed on the modified MS medium with auxin 2,4-D added at different concentrations: 5; 7 and 10 mg·dm⁻³, the MS0 medium without growth regulators was our control. To verify the effect of light conditions, half of explants were incubated in the light, and half in the dark. After 10 weeks of culture, the regenerated embryos were isolated, counted and measured. They were produced on all the media types, in both light conditions. The present research confirmed a positive effect of 2,4-D and light on the number of explants forming embryoid structures and on the number of regenerating embryos. The most number of embryos per 1 explant (1.8) were obtained on the MS7 medium (7 mg·dm⁻³ 2,4-D) in the light conditions.
Genetic and phenotypic stability of plants obtained via somatic embryogenesis may be disrupted. The reason can be an indirect regeneration of somatic embryos via callus or a high concentration of growth regulators added at the induction stage of somatic embryos. Somatic embryogenesis of ‘Lady Salmon’ (chimeric) and ‘Lady Vitroflora’ (non-chimeric) cultivars was induced on modified Murashige and Skoog (MS) media, supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D) and kinetin (KIN) or 6-benzylaminopurine (BAP). Flow cytometry (FCM) revealed that the plants derived from somatic embryos of both cultivars maintained the ploidy of control plants obtained from the meristem. The colour and pigment content of the inflorescence of plants derived from somatic embryos of ‘Lady Vitroflora’ were similar to the original control plants. However, the ray florets of clones of ‘Lady Salmon’ did not contain carotenoids, characteristic for this cultivar, and consequently produced flowers of different colours. Thus, somatic embryogenesis in chrysanthemums can be applied for separating periclinal chimera components for chimeric cultivars and for receiving an additional source of variation in the breeding of cultivars. In the case of genetically homogeneous cultivars it can be used in production laboratories for cloning plants in vitro via somatic embryogenesis.
The present research investigated the number of chromosomes in the cells of apical meristems of roots for three original Dendranthema grandiflora Tzvelev cultivars and the derivative cultivars obtained due to radiomutation. It was shown that only in one mutation cultivar, ‘Bronze Wonder’, the number of chromosomes differed from that of the original cultivar, ‘Lilac Wonder’.
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