Abstract. Daucus carota L. cell lines secrete a characteristic set of arabinogalactan proteins (AGPs) into the medium. The composition of this set of AGPs changes with the age of the culture, as can be determined by crossed electrophoresis with the specific AGP-binding agent, g-glucosyl Yariv reagent. Addition of AGPs isolated from the medium of a non-embryogenic cell line to an explant culture initiated the development of the culture to a non-embryogenic cell line. Without addition of AGPs or with addition of carrot-seed AGPs an embryogenic cell line was established. Three-month-old embryogenic cell lines usually contain less than 30% of dense, highly cytoplasmic cells, i.e. the embryogenic cells, but when carrot-seed AGPs were added this percentage increased to 80%. Addition of carrot-seed AGPs to a two-year-old, non-embryogenic cell line resulted in the re-induction of embryogenic potential. These results show that specific AGPs are essential in somatic embryogenesis and are able to direct development of cells.

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J. 1995. Somatic emhryogenesis of Cyclamen persicum in liquid medium. -Physiol. Plant. 94: 605-612.A method is described for the production of somatic embryos of Cyclamen persicum Mill, in liquid medium. Five steps are involved; initiation of embryogenic cell lines, proliferation of pro-embryogenic masses (PEMs) on auxin-containing medium, development of somatic embryos on hormone-free medium with high osmolarity, germination and subsequent piantlet formation. Cell lines were initiated by culturing the explant. the seedling tuber, directly in liquid medium. Three parameters were important for obtaining embryogenic cell lines: explant density, hormone concentrations and subculture regime. The rate of uptake of the hormones 2,4-dichlorophenoxyacetic acid (2,4-D) and kinetin influenced the formation of PEMs. Highly embryogenic cell lines were obtained only when PEMs had formed within 5-7 weeks. PEMs were proliferated for at least 24 months and could be isolated from each subculture for the production of somatic embryos. A high sucrose content (175 mA/) in the development medium without hormones ensured efficient embryo development from PEMs. A subsequent subculture in low sucrose concentration (58 mA/) induced tbe formation of a tuber, thus promoting gennination. Arabinogaiactan-proteins (AGPs) from carrot seeds and AGPs bound by the monoclonal antibody ZUM 18 increased the number of PEMs in a culture, showing that the activity of AGPs is not species specific.Key words -Arabinogaiactan-proteins, Cyclamen persicum.. somatic embryogenesis. M. Kreuger {corresponding author} et ai. S&G Seeds,

J. 1996. Genetically stable celi lines of cucumber for the large-scale production of diploid somatic embryos. -Physiol. Plant. 97: 303-310.For the initiation of embr\'ogenic cucumber (Cucumis sativus L.) cell lines, from excised radicles, directly in liquid medium, the culture regime, explant density' and type and concentration of hormones were adjusted so that pro-embryogenic masses (PEMs) were formed within about 8 weeks. The established cucumber cell lines were maintained for severai years without loss of embryogenic and genetic stability. The ploidy level of somatic embryos from different cucumber eel! lines was either diploid or tetraploid and depended on the ploidy level of Ihe cell line. Cucumber cell lines that produced only diploid embryos were obtained by selecting completely diploid explant material and growing 11 in the dark during the initiation phase, Mixoploid explants could lead to tetraploid or mixoploid cell lines. Isolation and additional selection and subculturing of single PEMs resulted in either completely diploid or tetraploid eel! lines, indicating that all ceils of individual PEMs are either diploid or tetraploid. The embryogenic cucumber cell lines, differing only in ploidy level, were indistinguishable in growth rate and embrj'ogenic potential and were genetically stable over several years. Kev words -Cucumis sativus, genetic stability, somatic embryogenesis.M. Kreuger (corresponding author,.^48) et aL.