In this study, we analyzed the morphological, cytological, and molecular changes induced by different doses of 60Co-γ radiation on root cuttings of the ground-grown chrysanthemum ‘Pinkling’ plants whose survival and height were decreased with increasing radiation dose. A variety of mutants were observed among irradiated ‘Pinkling’ plants; floral mutations included alteration of floral types, term ligulate floret number, capitulum diameter, and floral colour. Meiotic observation of mutants showed that the frequency of chromosome aberrations increased with radiation dose. The mutants were further analyzed using ISSR markers and on the basis of polymorphic DNA banding patterns, floral mutants were genotypically distinguished. Eighteen polymorphic ISSR primers produced 110 scorable bands, of which 93 (84.5%) were polymorphic. The percentage of polymorphism ranged from 60% to 100%. Jaccard’s dissimilarity coefficients varied from 0.337 to 1.000, which attested to the high genetic variability induced by irradiation. It is concluded that gamma ray irradiation induces a sufficient frequency of mutations and that ISSR analysis may offer a useful molecular marker for the detection of mutants in chrysanthemum. The present findings provide valuable information for future breeding of ‘Pinkling’.

The current study investigated the effects of gamma radiation on the death rate, morphological traits and meiotic abnormalities in ground-grown chrysanthemum ‘Donglinruixue’, and inter-simple sequence repeat (ISSR) markers were used to identify the DNA polymorphism among mutants. The results showed that the death rate significantly increased with increase in radiation dose. Semi-lethal (LD50) dose was approximately 35 Gy. Compared with unirradiated control, plant growth was significantly inhibited. After irradiation, a series of morphological variations and cytological aberrations occurred in radiated plants. The peak in variation frequency appeared at 35 Gy. In total, ISSR analysis produced 72 scorable bands, of which 64 (88.89%) were polymorphic. The current study demonstrated that gamma irradiation generates a sufficient number of induced mutations and that ISSR analysis offered a useful molecular marker analysis for the identification of mutants.

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