Confirmation of hybridity using GISH and determination of 18S rDNA copy number using FISH in interspecific F(1) hybrids of Tecoma (Bignoniaceae).

Interspecific hybridization in Tecoma Juss. was conducted to develop novel forms for the nursery industry. We report fertile hybrids from the cross T. garrocha Hieron. (pistillate parent) × T. stans (L.) Juss. ex Kunth. Leaf morphology of the F(1) hybrids of T. garrocha × T. stans was intermediate between the parents. GISH also confirmed hybridity. The F(1) hybrids were successfully backcrossed to both parents and self-pollinated to produce BC and F(2) progeny. Tecoma garrocha , T. stans, and T. guarume A. DC. 'Tangelo' were self-fertile. The F(1) hybrids also were crossed with T. capensis (Thunb.) Lindl. and T. guarume 'Tangelo', resulting in three-species hybrids. FISH conducted on F(1) hybrids identified four copies of the 18S internal transcribed spacer region. Further analysis using FISH has the potential to provide information on the evolution of Bignoniaceae and the potential role of polyploidy.