INTERSPECIFIC SOMATIC HYBRIDS BETWEEN WILD POTATO SOLANUM ACAULE BITT. AND ANTHER-DERIVED DIHAPLOID POTATO (SOLANUM-TUBEROSUM L.)

Solanum acaule Bitt. is a disomic tetraploid (4x) wild potato species which is resistant to several potato diseases. Introgression of diseas e resistance and abiotic stress tolerance to the tetrasomic tetraploid (4x) cultivated potato (S. tuberosum L.) gene pool via crossing has b een limited due to the difference in the endosperm balance number. In the present study, protoplast fusion was applied to produce hexaploid (6x) somatic hybrids between the parental lines, tetraploid (4x) S. ac aule and two anther derived dihaploid (2x) lines of S. tuberosum cv. W hite Lady. One callus (0.4%) of a total of 229 calli obtained regenera ted into shoots in the fusion combination S. acaule (+) White Lady 15. dh.8.2.2. All the regenerated shoots were confirmed to be interspecifi c somatic hybrids using species-specific RAPD markers. In another fusi on combination, S, acaule (+) White Lady 7.dh.23.1.1, fifteen calli (5 %) regenerated into a total of sixteen shoots from 289 calli. All the analysed somatic hybrids between S. acaule and S. tuberosum were hexap loid. The mean DNA content (2C value) of the combination S. acaule (+) White Lady 15.dh.8.2.2 somatic hybrids (4.55 pg), was approximately t he sum (4.69 pg) of the DNA contents of the parental lines, S. acaule (2.95 pg) and S. tuberosum (1.74 pg). In the greenhouse, the two somat ic hybrids analysed were normal in their morphological characteristics and more vigorous than their parental lines. Most of the morphologica l characteristics were closer to the tetraploid S. acaule than to the dihaploid S. tuberosum. The interspecific somatic hybrids are currentl y being tested for frost tolerance and glycoalkaloid composition.