2018 ASHS Annual Conference

Woody plant breeding is a long-term commitment and a breeding cycle usually takes 5-30 years. Cross incompatibility (late abortion) and seed germination are challenging and time-consuming. To speed up woody plant breeding cycles, immature embryo germination in vitro were investigated and reviewed. To avoid embryo abortion and pest and disease contamination, immature embryos should be excised from the mother plants as soon as they are visible and could be removed from the fruits. After fruit maturation, it is hard to dissect embryos and prepare sterilized explants for culture. Timing to collect immature embryos should be investigated bi-weekly or monthly. Majority of immature embryos should be placed in dark conditions for the first two weeks for initiation of germination. Quarter strength of Murashige and Skoog (MS) medium should be explored for the initial germination and other media such as WPM with extra sugar could work as well. Each germinated micro-seedling is a clone and we can regenerate it through micro-cuttings and/or somatic embryogenesis. Woody horticultural plants (Ilex crenata and Kalmia latifolia as examples) with successful immature embryo germination (embryo rescue) had been reviewed and summarized. Successful immature embryo germination should be able to avoid late embryo developmental abortion and yield cross breeding seedlings at the same growing season for woody plants, instead of additional 1-3 years for seed harvesting and germination. The procedures for immature embryo germination were technically challenged, but significantly speeded up woody plant breeding cycles.