ISHS Acta Horticulturae 131: In Vitro Culture, XXI IHC
BREEDING OF LOW TEMPERATURE TOLERANT POINSETTIA (EUPHORBIA PULCHERRIMA) AND CHRYSANTHEMUM BY MEANS OF MUTATION INDUCTION IN IN VITRO CULTURE |
| Authors: | W. Preil, M. Engelhardt, F. Walther |
| Abstract:
Single cells and small aggregates from suspension cultures of poinsettia, cv. "Preduza" and of chrysanthemum, cv. "Puck" were x-irradiated and then exposed for 170 days to in vitro stress temperatures (poinsettia: 12° C; chrysanthemum: 8° C). Calli with embryo like structures and initiated shoot differentiations were transferred to optimal temperatures (24° C) at the end of the stress period. Regenerated plants were grown in greenhouse under natural short-day conditions up to flowering at stress temperatures: 14° C / 12° C (day/ night) for poinsettia and 10° C / 10° C for chrysanthemum. Among 977 tested poinsettias only four plants were selected representing the cultivar-typical phenotype but without leaf-shedding during low temperature stress. 16 plants among 2 112 chrysanthemums induced flowers at 10° C. This demonstrates that most of the plantlets selected after in vitro temperature stress were no mutants. They are obviously non-heritable phenotypes with modified physiological response (epigenetic changes). In experiments to confirm the mutatively changed nature of the few selected plants following clonal propagation three poinsettia clones proved to be slightly better adapted to low greenhouse temperatures compared to the original cultivar. The differences were of high statistical significance. Two selected chrysanthemum clones flowered 7 – 10 days earlier than the original variety under summer greenhouse conditions as well as under 14° C or 10° C temperature regime. These plants are considered as real physiological mutants. | |
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