Somatic hybridization between an albino Cucumis melo L. mutant and Cucumis myriocarpus Naud.

Abstract

Cotyledon-derived protoplasts of an albino Cucumis melo L. mutant were electrofused with protoplasts of Cucumis myriocarpus Naud. Putative somatic hybrids were selected on the basis of albinism complementation and the different behaviour of the protoplast-derived cells of the parental species in a definite sequence of culture media. Somatic hybrids were characterized at a molecular level and we confirmed that the green calli recovered after fusion were interspecific hybrids. RFLP patterns that identify C. melo albino mutant and C. myriocarpus genomes could be obtained by digestion of PCR-derived DNA fragments containing the 18S–25S ribosomal DNA (rDNA) spacer region with the endonuclease Sau3A. This procedure revealed that all of the putative somatic hybrids had the C. melo Sau3A pattern band and only one showed the Sau3A pattern bands corresponding to both parents. In order to confirm that the selected calli were hybrids, a specific oligonucleotide MYR2 was designed according to the sequence diversity within the internal transcribed spacer (ITS) regions of C. melo and C. myriocarpus. ITS1 and MYR2 primers were used to specifically amplify an rDNA fragment of 457 bp from C. myriocarpus. As expected, the selected calli recovered after the fusions, contained the C. myriocarpus genome. Since these calli also showed the RFLP melon pattern it was clear that these hybrids combined both parental genomes.