An integrated approach to overcome crossing incongruity in woody ornamentals

In woody ornamentals, interspecific hybridisation offers enormous possibilities to introgress new and desired traits in commercial plant species. In interspecific crossing programs of Rhododendron, Hibiscus and Buddleia multiple crossing incongruities could be observed: pollen tube growth inhibition and ploidy differences as well as absence of seed germination, hybrid albinism and lack of growth vigour. Frequently, also unilateral crossing incompatibility was seen. After most crossings embryo rescue was a necessary step to overcome some of these barriers. In obtained interspecific F1-hybrids of Hibiscus evidence for the production of unreduced gametes could be found.