ISHS Acta Horticulturae 1007: II All Africa Horticulture Congress
INVESTIGATION OF CROSSING BARRIERS BETWEEN CALIBRACHOA AND PETUNIA SPECIES |
| Authors: | S. Olschowski, L. Meyer, V. Mußmann, M. Serek |
| Keywords: | embryo formation, interspecific hybridization, pollen tube growth, pollination |
| DOI: | 10.17660/ActaHortic.2013.1007.90 |
| Abstract:
Supercal and Calitunia are examples of known hybrids of Petunia and Calibrachoa. It is, however, not known if they are results of sexual crosses or protoplast fusion. Between the genera, there are presumably barriers for interspecific crossings. These barriers have been investigated in our study with an attempt to overcome them. Investigations of pollen tube growth in the stylus, growth of pollen tubes into the ovaries and embryo formation in different crossing combinations were performed. Pollen tubes grew completely through the style in all crossing combinations except Calibrachoa × Petunia. In further experiments the crossing variant Petunia × Calibrachoa showed 85% pollen tube growth in the ovaries, 15% in Petunia × Supercal and 95% Supercal × Calibrachoa. Genotypic differences in the crossing acceptance using different Petunia and Calibrachoa genotypes were also observed. Embryo formation was successful in Petunia × Calibrachoa with 75, 85% in Supercal × Calibrachoa, but only 5% embryo formation in Supercal × Petunia. In all of these crosses, however, no seeds germinated upon sowing. Termination of embryo development in the early stage was probably caused by post-fertilization barriers. Some of these barriers might be overcome by embryo rescue methods. In vitro pollination was tested, but no ingrowth of pollen tubes into the egg cells was observed. | |
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