Introgression of yellow flower colour in Buddleja davidii by means of polyploidisation and interspecific hybridisation

Van Laere K., Van Huylenbroeck J., Van Bockstaele E. , 2011. Introgression of yellow flower colour in Buddleja davidii by means of polyploidisation and interspecific hybridisation . Hort. Sci. (Prague), 38: 96–103. To introduce yellow colour in the commercial Buddleja davidii (2n = 4x = 76) assortment, an interspecific breeding programme with B. globosa (2n = 2x = 38) was started. The first step was to perform chromosome doubling in B. globosa. Two of the obtained tetraploid B. globosa plants were subsequently used as male parent in interspecific crosses with the white flowering B. davidii cv. Nanhoensis Alba. In total 182 interspecific crosses were made and 18 F1 hybrids were obtained. Genome size measurements, chromosome counts and genomic in situ hybridisation (GISH) analysis proved the hybrid nature of most of the F1 hybrids. Plant morphology also expressed hybrid characteristics. F1 seedlings inherited the yellowish flower colour from