ELECTROFUSION OF PROTOPLASTS OF ANTHER-DERIVED DIHAPLOID LINES OF COMMERCIAL POTATO CULTIVARS

Somatic hybrids of anther-derived dihaploid (2x) potato (Solanum tuber osum L.) lines were produced by electrofusion of protoplasts. Using RA PD (randomly amplified polymorphic DNA) markers, six new combinations of dihaploid parental lines from cultivars Matilda, Nicola, Pito, Stin a, Van Gogh and White Lady were identified. RAPD marker identification of the putative hybrids was mostly done using two distinct parental l ine specific primers. 43% of the 76 regenerated calli from the six com binations produced hybrid shoots. Most of the somatic hybrids were tet raploid (4x), but in four fusion combinations plants of hexaploid (6x) , octoploid (8x) or mixoploid level were also identified by chromosome counts or flow cytometric nuclear DNA analysis. The mean nuclear DNA content (2C value) of the tetraploid and hexaploid somatic hybrids was lower than the expected DNA content (i.e. the 2C values of the origin al tetraploid cultivars or the sum of the 2C values of the dihaploid f usion parents). Some somatic hybrids having the expected nuclear DNA c ontent were also found.