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Random amplified polymorphic DNA (RAPD) markers were used to study the molecular characterization of 10 new radiomutants of chrysanthemum. The original cultivar ÔRichmondÕ differed in genetic distance from its Lady group mutants. The analysis of genetic similarity indices revealed low diversity within the radiomutants. The dendrogram obtained after cluster analysis separated the new cultivars as a group that differed from the original cultivar ÔRichmondÕ. The Lady group cultivars, derived from one original cultivar by radiomutation, could be distinguished from each other by using RAPD markers of only a single primer or sets of two or three primers. Polymerase chain reaction analysis proved the efficiency of the RAPD method for DNA fingerprinting of the original cultivar ÔRichmondÕ and its new radiomutants.

The subject of investigation was Chrysanthemum x grandiflorum (Ramat.) Kitam., FSatinbleu_. Leaf explants and internodes were excised from the middle part of the donor sterile plant. Two methods of explant inoculation were applied: explants were placed polarly and horizontally. Modified MS medium (Murashige and Skoog 1962), supplemented with 11.4 μM indoleacetic acid and 2.7 μM 6-benzylaminopurine, were prepared to induce adventitious bud formation. Four dates of explant inoculation on the medium were tested: January 15, April 15, July 15, and October 15. Thus, regeneration occurred in winter, spring, summer, and autumn. In the present study, a more intensive regeneration in FSatinbleu_ chrysanthemum was observed in summer and autumn than in spring and winter, irrespective of the kind of explant and the inoculation method.

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Chrysanthemums are amongst the most economically important flowers in the world. The protection and storage of these valuable genetic resources is of great importance. Today, cryopreservation, or the storage of biological material at the temperature of liquid nitrogen (-196°C), is believed to be the most promising long-term storage method. To optimise the cryopreservation protocol, the shoot tips of Chrysanthemum × grandiflorum /Ramat./ Kitam. 'Lady Orange' and 'Lady Salmon' mutants were cryopreserved using the encapsulation-dehydration technique. During the experiment, the influence of sucrose concentration (2, 3 and 6%) during preculture and the concentration of kinetin (0.25, 0.5, 0.75 and 1.0 mg dm -3 ) in the regrowth medium were tested. A higher survival rate was observed for 'Lady Salmon'. In general, the media with higher sucrose levels provided the best survival and recovery rates (35-40%). Kinetin had no influence on the survival rate; however, it influenced the morphogenesis of the plants. The lowest number of explants forming multiple shoots was observed on the medium with the lowest sucrose (during preculture) and kinetin (in the recovery medium) concentration. On the other hand, the best rhizogenesis efficiency was observed when 0.25 mg dm -3 kinetin was added. In conclusion, the composition of both preculture and recovery media need to be adjusted to single cultivars. The use of 3% sucrose (preculture) and 0.25 mg dm -3 kinetin (recovery) seems reasonable, since it guarantees a satisfying recovery rate of the explants and at the same time prevents the formation of callus and multiple shoots, stimulating the rooting instead.

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