PRODUCTION AND IDENTIFICATION OF SOMATIC HYBRIDS BETWEEN SOLANUM-TUBEROSUM AND S-PAPITA BY USING THE ROLC GENE AS A MORPHOLOGICAL SELECTABLE MARKER

A successful hybridization of a diploid clone of Solanum tuberosum wit h a rolC-transgenic, diploid S. papita clone is reported. By using lea f explants of this S. papita clone, which after transformation express ed kanamycin resistance, intact protoplasts were obtained, but these p rotoplasts did not develop to microcalli or regenerate to mature plant s. However, protoplasts of the S. tuberosum clone showed a high capaci ty to regenerate plants from isolated protoplasts. On a medium contain ing kanamycin only calli regenerated to plants, which revealed a rolC phenotype (reduced apical dominance with a large number of adventitiou s shoots and a pale green color of leaves) and later on turned out to be true hybrids. Self fusions of S. papita never developed to microcal li and those of S. tuberosum ceased to develop on the kanamycin-contai ning medium. Identification of somatic hybrids was done by RFLP and RA PD analysis. In the greenhouse, out of four selected hybrids only FK3. 1 was successfully crossed with two standard S. tuberosum varieties (D atura, Desiree). Out of all the seeds germinated, only rolC-negative F -1 seedlings were further characterized. Within the seedling populatio n obvious differences were evident in respect of the S. papita and S. tuberosum characteristics.