Micro-Tuber Production in Diploid and Tetraploid Potato after Gamma Irradiation of <i>in Vitro</i> Cuttings for Mutation Induction

Abstract

Micro-tubers are important propagules in potato breeding and potato production, and they are also dormant and easily transported and therefore good targets for mutation induction in potato mutation breeding. A prerequisite for mutation breeding is to determine optimal mutation treatments . Therefore, radio-sensitivity tests of a tetraploid and a diploid potato to gamma irradiation were undertaken. Effects of different gamma sources on radio-activity were also studied. In vitro potato cuttings were gamma irradiated using a wide dose range (0, 3, 6, 9, 12, 15 and 20 Gy). The irradiated cuttings were then cultured to induce micro-tubers directly in vitro . Micro-tuber morphotypes were assessed after irradiation of cuttings using three gamma sources with emission activities of 1.8, 7.07 and 139 Gy/min. The diploid species ( Solanum verrucosum ) was more radio-sensitive than the tetraploid cultivar Desirée ( Solanum tuberosum ). Gamma dose rates had significant influences on subsequent micro-tuber production at various mutant generations. Effects included reductions in the number, size and weight of micro-tubers produced. Gamma dose was more lethal for the diploid potato genotype and micro-tubers produced were small compared to those produced by the tetraploid genotype after irradiation. Different treatments are recommended for diploid and tetraploid potato irradiation in producing large mutant micro-tuber populations. The mutant micro-tuber populations may then be screened for interesting mutations/trait for both genetics and plant breeding purposes.