Effect of Irradiation Conditions on Mutation Rate Induced by Gamma-Ray Irradiation in Foxtail Millet (Setaria italica (L.) P. Beauv.)

Foxtail millet (Setaria italica (L.) P. Beauv.) is a highly self -pollinated diploid grass of Eurasia, which shows a remarkable morphological diversity. Recent studies suggest that foxtail millet can be a suitable cereal for genetic and molecular studies. Mutants provide good information on the genetics of morphological diversity. In the present paper, effects of irradiation conditions on mutation rate induced by gamma-ray irradiation in foxtail millet are reported. Seeds were irradiated with gammarays under dry and wet conditions. Then the growth of M_1 plants, and the frequency and kind of chlorophyll mutants in the M_2 generation were examined. Difference in irradiation conditions influenced the growth of M_1 plants little, but it greatly influenced the rate of chlorophyll mutation. The xantha trait was induced as four to seven times as frequently as the albino trait, which was opposite to the result obtained in rice. Considering the genome conservation in the grass family, this result has many implications. The frequency of chlorophyll mutants in Mi panicles was less than 25 % in most cases, suggesting that the panicle of foxtail millet is derived from plural initial cells