Shoot formation from explant cultures of fourteen potato cultivars and studies of the cytology and morphology of regenerated plants

Plants were regenerated in quantity from cultured excised stem, rachis or leaf pieces of 13 potato (Solarium tuberosum L.) cultivars using modifications of a two-step procedure. Pronounced differences were observed in the response of different cultivars and explant sources to medium formulations containing different auxins or cytokinins. A few plants were recovered from tuber pieces of seven cultivars by a different two-step procedure. Morphological differences from control plants were observed in some of the primary regenerants. Anthocyanin pigmentation of tubers was scored and stable changes to red-splashed white or white tubers were found in some plants regenerated from cv. Desiree. Regenerants from the particoloured cultivars Cara and King Edward often lost this trait but it returned to varying extents in subsequent generations. Most of the regenerated plants (87 per cent) contained the euploid number of chromosomes (2n = 4x = 48). The methods are suitable for production of plants for assessment of somaclonal variation in a range of genotypes.