IN-VITRO REGENERATION AND CYTOLOGICAL CHARACTERIZATION OF SHOOTS FROM LEAF EXPLANTS OF 3 ACCESSIONS OF SOLANUM-COMMERSONII

In vitro culture of explants were used to apply genetic or cell enginerring techniques to the sexually incompatible potato relative Solanum commersonii (2n = 2x = 24) Three accessions of S. commersonii were tested for regeneration from leaf explants using six different protocols. A two step-regeneration procedure gave the best results. Genetic variability for regeneration ability was found between accessions, and between clones within accessions. The accession PI 472834 regenerated at highest frequency. Clones with high regeneration ability were selected. Approximately 60% of regenerated plants were diploids and 40% were tetraploids. A very low frequency of chimeras was found. Leaf shape and chloroplast counts in guard cells were shown to be quick and reliable methods for estimating ploidy levels. Use of the diploid and tetraploid regenerants obtained for potato breeding is discussed.