Production of Interspecific Hybrid Plants in Primula

The methods of production of inter-specific hybrids in Primula are categorized into four steps: (1) emasculation, (2) pollination, (3) rescue culture of immature embryo, and (4) confirmation of hybridity and ploidy level of the regenerated plants. Although most of the Primula species have a heteromorphic self-incompatibility system, an emasculation step is usually needed to avoid self-pollination since self-incompatibility is not always complete. At the rescue culture step, addition of plant hormones (e.g., auxin, cytokinin, and gibberellin) to the culture medium is proved to be effective. The hybridity of the plants is efficiently confirmed at seedling stage by DNA analysis in addition to the comparison of morphological characters. The analysis of relative DNA contents by flow cytometry is easy and rapid technique to confirm hybridity and to estimate ploidy level and genomic combination.