Comparison of in vitro haploid induction in balm (Melissa officinalis)

The generation of haploids in lemon balm (Melissa officinalis L.) is the prerequisite for accelerated development of homozygous lines. Wide experiments to induce sporophytic development were arranged. Donor plants of lemon balm were established in a greenhouse, climate chambers and in vitro. For haploid induction, different variations of media and culture conditions e.g. pretreatment with cold and heat were tested. Sporophytic development of pollen was induced in anther and microspore culture. Callus developed sporadically in anther culture. Multi-cellular structures and microcallus generated from microspores. In vitro cultivated ovules became dark brown and somatic callus generated at the cut surface. Cultivation of ovaries maintained swelling on medium, but undeveloped embryos died.