Regeneration and molecular characterization of a male sterile interspecific somatic hybrid between Cichorium intybus and C. endivia

A single plant exhibiting male sterility was found among 288 regenerants derived from fusions between protoplasts of Cichorium intybus var. Cassel and protoplasts of C. endivia var. Traviata. The male sterility was characterized by the presence of non-dehiscent blue anthers without pollen or with very few non-viable pollen. The chloroplast genome seemed to be identical to that of C. intybus, and mitochondrial analysis by Southern hybridizations with mitochondrial probes showed fragments from two plants. Use of microsatellites as nuclear markers confirmed the hybrid nature of the tetraploid male sterile plant. The male sterility was maintained in a small progeny obtained from backcrosses with diploid fertile C. intybus var. Cassel and would be confirmed by two consecutive crosses with tetraploid fertile genotypes. This is the first time that a male sterile hybrid has been produced by protoplast fusion between two sexually compatible Cichorium species.