Transfer of PLRV resistance from Solanum verrucosum Schlechdt to potato (S-tuberosum L.) by protoplast electrofusion

Somatic fusions between an accession of the diploid wild species Solanum ve rrucosum and a dihaploid S. tuberosum genotype were produced in order to in corporate resistance to potato leafroll virus (PLRV). In total 15 somatic h ybrids out of 16 regenerants were obtained. Identification of hybrids was b ased on additive RAPD patterns, general morphological characteristics, chro mosome numbers and chloroplast counts in stomata guard cells. A field trial was performed with the hybrids, their two parents and the control cultivar Kennebec to assess field performance and phenotypic variability. Yield par ameters varied considerably among somatic hybrids. Some of the hybrids gave significantly higher yields, tuber numbers and tuber weights than both par ents. Pollen fertility of hybrids ranged from 19 to 77%. Twelve hybrids wer e found to be resistant to PLRV.