In the present study, the applicability of four wide-spectrum light-emitting diodes (LEDs) emitting warm light (AP67, AP673L, G2, and NS1) was determined for the micropropagation of five popular ornamental plant species: Chrysanthemum × grandiflorum, Gerbera jamesonii, Heuchera × hybrida, Ficus benjamina, and Lamprocapnos spectabilis. Plantlets were grown in a growth room with a 16-h photoperiod. The photosynthetic photon flux density was set at 62-65 μmol m −2 s −1. The composition of the media and subculture timing were adjusted to the needs of each species tested. The results were compared to the cool daylight-emitting fluorescent (FL) control (TLD 36W/54). In most of the species studied (except for F. benjamina), the highest propagation ratios, or ratios similar to the FL control, were observed under the red-and far-red-abundant G2 LEDs. NS1 spectrum (with the highest proportion of blue and green light) was also efficient for G. jamesonii and L. spectabilis, and it provided a similar propagation ratio as the FL control. Light quality affected shoot length, number of leaves, callus regeneration, and the biosynthesis of chlorophyll. This influence, however, was species-dependent. Lighting conditions did not affect the dry matter and rooting in most of the species tested, except for G. jamesonii. The substitution of FLs with G2 LEDs can result in a 50% reduction of annual electricity costs, while the application of NS1 lamps can generate savings of up to 75%. In conclusion, the G2 LED lighting system seemed to be the most suitable in terms of propagation efficiency, plantlet quality, and cost reduction.

No abstract

Classical mutation breeding using physical factors is a common breeding method for ornamental crops. The aim of our study was to examine the utility of ovaries excised from irradiated inflorescences of Chrysanthemum × morifolium (Ramat.) as explants for breeding purposes. We studied the in vitro regeneration capacity of the ovaries of two chrysanthemum cultivars: ‘Profesor Jerzy’ and ‘Karolina’ preceded by irradiation with high-energy photons (total dose 5, 10 and 15 Gy) and high-energy electrons (total dose 10 Gy). Growth and inflorescence parameters of greenhouse acclimatized regenerants were recorded, and ploidy level was estimated with flow cytometry. The strong impact of genotype on regeneration efficiency was recorded—cultivar ‘Karolina’ produced only 7 viable shoots, while ‘Profesor Jerzy’ produced totally 428 shoots. With an increase of irradiation dose, the regeneration decreased, the least responsive were explants irradiated with 15 Gy high-energy photons and 10 Gy high-energy electrons. Regenerants of ‘Profesor Jerzy’ obtained from these explants possessed shorter stem and flowered later. The highest number of stable, color and shape inflorescence variations were obtained from explants treated with 10 Gy high-energy photons. Variations of inflorescences were predominantly changes of shape—from full to semi-full. New color phenotypes were dark yellow, light yellow and pinkish, among them only the dark yellow phenotype remained stable during second year cultivation. None of the regenerants were haploid. The application of ovaries irradiated within the whole inflorescence of chrysanthemum can be successfully applied in the breeding programs, provided the mother cultivar regenerate in vitro efficiently.

No abstract

No abstract

In chrysanthemum, breeders seek for desirable characteristics of the inflorescence, which can first be established once the plant is mature. The present study aims to determine whether measurement of DNA content can be useful in the detection of somaclonal variants and/or separation of chimera components in chrysanthemum at the early in vitro multiplication stage. Eleven Chrysanthemum × morifolium (Ramat.) Hemsl. cultivars of the Lady group (a mother cultivar and ten of its radiomutants obtained by X-ray- or γ-irradiation; solid and periclinal chimeras) were propagated in vitro. Single-node explants were cultured in Murashige and Skoog (MS) medium, either without plant growth regulators (PGRs) or supplemented with 6-benzyladenine (BA) and indole-3-acetic acid (IAA). The nuclear DNA content was measured by flow cytometry (FCM) in the shoots produced in vitro. After acclimatization and growth of the plants in a glasshouse, inflorescence colour was recorded. The addition of PGRs to the medium almost doubled the mean number of shoots produced in vitro per explant, but caused a change in inflorescence colour of all (‘Lady Apricot’; periclinal chimera) or part of the plants (‘Lady Amber’; solid mutant and ‘Lady Salmon’; periclinal chimera). All radiomutants contained less DNA than the mother cultivar ‘Richmond’. There were significant differences in DNA content between plants of the same cultivar grown in media with or without PGRs for ‘Lady Apricot’ and ‘Lady Salmon’, but no phenotype alternation occurred in chrysanthemums produced in PGR-free medium compared to the original cultivars. Conversely, in medium with PGRs, chimeras produced flowers different from the original colour. In all except one cultivar (‘Lady Amber’; solid mutant) a lack of differences in genome size between plants grown in either medium coincided with a stable inflorescence colour. The occurrence of some plants of ‘Lady Amber’ with different inflorescence colour may be due to small DNA changes, undetectable by FCM. It can be concluded that FCM analysis of DNA content in young plantlets can be indicative of the stability of inflorescence colour in chrysanthemum, especially chimeric cultivars, and for mutant detection.

No abstract

No abstract