ISHS Acta Horticulturae 280: I International Symposium on In Vitro Culture and Horticultural Breeding
SOMATIC MUTAGENESIS OF GERBERA JAMESONII HYBR.: IRRADIATION AND IN VITRO CULTURE |
| Authors: | U. Laneri, R. Franconi, P. Altavista |
| Abstract:
Shoots from in vitro plantlets of the pink gerbera cv. Rebecca were irradiated with a single dose of 20 Gy gamma rays (9,8 Gy/h) and then micropropagated for two cycles; after rooting, the plantlets were cultivated in the greenhouse and analysed for morphological mutations. Irradiation treatment induced a 25% reduction of propagation rates in each cycle. Out of 247 non-contaminated initial shoots, 129 (52%) produced a clonal progeny showing flower variations and among the 1250 adult plants derived from irradiated shoots, 187 (15%) were variants. The observed variations affected flower morphology (e.g. number, length and width of ligulae) and colour. Out of 187 MV2 variant plants, 6 plants (with at least 2 flowers) were presumably solid mutants. The remaining 97% showed chimerism at various levels: 44.4% plants had both normal and uniformly mutant flowers, 4.8% had different uniformly mutant flowers (intra-plant chimerism); 47.6% plants had flower deformations and/or colour sectors (intra-inflorescence chimerism). Out of 424 variant flowers, 147 (35%) were chimeric; of the uniformly variant flowers, 26% showed only single morphological variations, 13% only colour variations and the remaining flowers showed a combination. There were 13 morphological and 6 colour types of variants. In contrast, of 321 control plants derived from 40 non-irradiated shoots, none showed flower variation. We conclude that in 'Rebecca' more than two micropropagation cycles are necessary to increase the percentage of solid mutants. In spite of this limitation, the proposed scheme appears to be a quick tool to induce variability without gross genome modification. | |
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