2017 ASHS Annual Conference

Somatic embryogenesis, the process by which single somatic cells develop into plants, has become a valuable tool for genetic engineering. The ability to insert specific genes into plants is especially important for wine grapes because unique sensory components are lost in conventional breeding so that they cannot be improved by adding important traits such as disease resistance. However, Somatic embryos (SE) germination and the ability to grow them into plants remains a limiting factor in the pipeline of producing the number of plants needed for trait evaluation, especially for muscadine (Vitis rotundifolia Michx) grape. Other Vitis sp including Euvitis (the European, Vitis vinifera L. grapes and the American bunch grapes, Vitis labrusca L., are also difficult to germinate. An array of treatments were previously tested to improve the efficiency of SE germination and plant recovery. These include various concentrations of plant growth regulators partial desiccation, low-temperature storage or a combination of one or more of these treatments. For all of the plants reported here, germination of SEs and their conversion into plantlets have been improved significantly. Grape seeds need both cold treatment and desiccation to germinate, and by utilizing the same treatment for grape SEs, our hope was to improve the efficiency for their germination. Our objective was to determine whether cold and/or desiccation treatment will improve the germination and plant recovery of Vitis SEs. I hypothesized that a combination of temperature and desiccation treatments will be most effective in increasing embryo germination. SEs are routinely maintained on X6 (bunch grape) and DMX (muscadine) media. To initiate germination, cotyledonary-stage SE (CSE) will be selected for one of the following treatments after which they will be placed on a MS based germination media, with or without 6-Benzylaminopurine (BA). BA was previously found to improve grape somatic embryo germination. Cultivars tested: Existing somatic embryos of the Euvitis or bunch grape cultivar, Thompson Seedless (TS) and the Muscadine cultivar, Fry. Germination frequency was determined by counting the number of germinated SE with shoots and roots. Statistical analysis was accomplished to compare the relative germination percentages among the treatments to determine if any one was better than the BA or non-BA media controls. Results showed that shoots proliferated after four days when treated prior with 10 days of desiccation. Cold treatment gave rise to a dormant phase while combination treatments varied across cultivars.