Optimal dose of Gamma radiation for <i>Phaseolus vulgaris</i> L. cultivar 'BAT-93' <i>in vitro</i> plants regeneration

Abstract

The application of Gamma radiations combined with tissues cultures in common bean constitutes a tool to accelerate the programs of genetic improvement. The determination of the optimal radiation dose is an important aspect to be defined in order to generate genetic variability. For this reason, the objective of this study was to determine the optimal dose of Gamma radiation for regenerating Phaseolus vulgaris L. cultivar 'BAT-93'in vitro plants. It were applied doses of 20, 30, 40, 50 or 60, Gy to mature seeds and an unirradiated control was included. The seeds were in vitro germinated and the cotyledonary nodes with two cotyledon was used for callus formation. Per mutagenic treatment and the control without irradiation 100 seeds were used. The evaluations were made 21 days after the radiation was applied. The percentage of explants that formed calluses and its fresh weight (g) were recorded. With these values, the mean lethal dose (LD50) was determined. In the regeneration, the number of shoots per callus was determined, from these values the mean Reductive Dosage (GR50) was calculated. The main affectations occurred in the callus formation and in the shoots regeneration. The dose of 30 Gy was selected for the massive treatments of common bean cv. 'BAT-93' seeds with Gamma radiations. This dose was closer to the LD50 and GR50). Keywords:in vitro culture, common bean, radiosensitivity, seeds