In vitro methods for mutation induction in potato (Solanum tuberosum L.)
Potato (Solanum tuberosum L.) is an important vegetable and staple crop worldwide and mainly propagated vegetatively. Breeding of potato is problematic and therefore induced mutation is an attractive means of improving the crop. In vitro culture systems, and especially the production of microtubers, are ideal for such purposes in potato improvement. Radio-sensitivity testing (growth reduction, GR and lethal dose, LD) allows the determination of irradiation treatments (Gy) for mutation induction. Three schemes incorporating in vitro techniques were tested for mutation induction in potato namely: 1) irradiation of cuttings without leaves and subsequent dissociation of chimeras to produce plantlets or micro-tubers on M1V2 (or further generation) plantlets, 2) irradiation of cuttings with leaves and direct induction of mutant micro-tubers, and 3) induction and irradiation of micro-tubers. Variability among the potato genotypes to gamma irradiation was recorded. Optimized irradiation treatments for mutation induction were established for the various tissues/propagules: cutting growth (GR50, 9-6 to 20.6 Gy), cutting tuberization ability (LD50, 7.3 to 13 Gy) and micro-tuber sprouting ability (LD50, 20.6 to 54.8 Gy). Micro-tubers were found to be more resistant for in vitro mutation induction than in vitro cuttings. This study shows the susceptibility of different plant tissue/propagule and potato genotypes to gamma irradiation. Radio-sensitivity analyses showed that lower gamma doses are required when mutation induction is applied in combination with micro-tuberization.
Key words: Potato, gamma irradiation, stem cuttings, micro-tubers, in vitro tuberization.