Isolation and Callus Production from Cotyledon Protoplasts of Cucumis metuliferus

In North Carolina, approximately 8% of the cucumber (Cucumis sativus) yield is lost to root-knot nematodes (Meloidogyne spp.) (Main and Gurtz, 1989). No resistance was found in cucumber after screening of 900 cultigens for resistance to Meloidogyne incognita race 3 (Walters, 1991). African horned cucumber (Cucumis metuliferus) has resistance to M. incognita (Fassuliotis, 1967; Walters, 1991), as well as other diseases such as squash mosaic virus and watermelon mosaic virus (Provvidenti and Robinson, 1974). There would be benefit in transferring nematode resistance into the gene pool of C. sativus from C. metuliferus. However, traditional sexual hybridization techniques have been unsuccessful in producing hybrids between C. metuliferus and cucumber, probably due to differences in chromosome number (Deakin et al., 1971) or incompatibility barriers. In some crops, use of protoplast fusion has allowed barriers to sexual hybridization to be overcome.