Transformation of cucumber tissues by microprojectile bombardment: identification of plants containing functional and non-functional transferred genes.

The microprojectile bombardment method was used to transfer DNA into embryogenic callus of cucumber (Cucumis sativus), and stably transformed cucumber plant lines were obtained. A total of 107 independently regenerated cucumber plants were assayed for the presence and expression of the transferred Nos-NPTII gene (encoding nopaline synthase-neomycin phosphotransferase II). Genomic blot hybridization analyses showed that a high percentage (16%) of the cucumber plants were transformed with Nos-NPTII; however, only about 25% of these transgenic plants expressed Nos-NPTII. Inactivity of Nos-NPTII in many of the transformed cucumber plants may be associated with the transfer of multiple copies of Nos-NPTII. PCR and genomic blot hybridization analyses were used to show that the transferred gene was inherited in the subsequent plant generation.