Confirmation of hybridity using GISH and determination of 18S rDNA copy number using FISH in interspecific F1hybrids ofTecoma(Bignoniaceae)

Abstract

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 F1hybrids of T. garrocha × T. stans was intermediate between the parents. GISH also confirmed hybridity. The F1hybrids were successfully backcrossed to both parents and self-pollinated to produce BC and F2progeny. Tecoma garrocha , T. stans, and T. guarume A. DC. ‘Tangelo’ were self-fertile. The F1hybrids also were crossed with T. capensis (Thunb.) Lindl. and T. guarume ‘Tangelo’, resulting in three-species hybrids. FISH conducted on F1hybrids 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.