Showing papers on "Mutation breeding published in 2003"

Wide variety of flower-color and -shape mutants regenerated from leaf cultures irradiated with ion beams

Abstract: The efficiency of ion-beam irradiation combined with tissue culture in obtaining floral mutants was investigated and compared with those of gamma rays and X-rays in carnation. Leaf segments of carnation plants in vitro were irradiated with the 220 MeV carbon ions, and cultured till the shoot regenerated. The carbon ion had the highest effect in reducing the regeneration frequency, and the RBE value with respect to gamma-rays was four. The higher mutation frequency and the wider mutation spectrum were obtained in plants irradiated with the carbon ions than low LET radiations. Three new carnation varieties developed by ion-beam irradiation were applied for the registration of the Japanese Ministry of Agriculture, Forestry and Fisheries. The results indicate that ion beam irradiation could induce wide variety of flower-color and -shape mutants, and that the combined method of ion-beam irradiation with tissue culture is useful to obtain the commercial varieties in a short time.

Zygotic embryo culture and mutation breeding in avocado (persea americana mill).

Abstract: Mutation induction and biotechnological techniques are current approaches used in plant breeding. At present work, both methodologies were combined in order to obtain a mutation-breeding model in avocado. In vitro germination and rooting of zygotic embryos, sprout multiplication and plantlets adaptation in Cuban avocado varieties were studied. Percentage of germinated entire embryos were higher using mature than immature embryos. Near of 80 % of entire plantlets obtained by embryo culture technique were adapted to greenhouse conditions. Based on inhibition of entire sprout fraction, radiosensibility curves for Duke and Hass varieties were developed. Inhibition of entire sprout fraction was described by a second order polynomial equation. Fit of experimental data and theoretical model was equal to 0.96 and 0.95 for Hass and Duke radiosensibility curves, respectively. LD50 values defined as the dose, at which the 50 % of entire sprout fraction are inhibited, were determined in 27 and 28 Gy for Hass and Duke varieties, respectively. Gamma-rays mutagenic doses for zygotic embryos of both varieties were also established between 19 and 25 Gy. Applied mutagenic dose did not affect significantly plantlets development. However, leaf and root anomalies, atrophied and chlorophyll-deficient shoots and albinism were observed at doses higher than LD50 values. The usefulness of the combined approach to improve avocado varieties was discussed. This in vitro methodology appears as an alternative to traditional breeding methods, particularly for improving agronomic characteristics as rot-root resistance and salt tolerance in avocado.