The present study confirms the occurrence of secondary somatic embryos in peach palm and describes a feasible protocol for regeneration of peach palm in vitro. Further optimizations include the use of explants obtained from adult palms and improvement of somatic embryo conversion rates.

The present study aimed at developing temporary immersion bioreactor techniques for multiplication of cacao somatic embryos. Temporary Immersion System (TIS), i.e. flooding of plant tissue at regular time intervals provides an efficient way to propagate plants. Somatic embryos were regenerated in twin flask bioreactors. The TIS proved to be suitable for mass regeneration of somatic embryos and for their subsequent direct sowing. The number of embryos after 3 months of culture was significantly higher in TIS cultures than in the solid medium variant. TIS also improved embryo development regarding the conversion to torpedo shaped forms. Matured embryos derived from TIS and pre-treated with 6% sucrose were converted into plants after direct sowing. Additionally to the influence of culture conditions on the development of somatic embryogenesis the content and composition of free amino acids were analysed. The content of free amino acids in somatic embryos rose as immersion frequency increased. The endogenous free GABA content in embryogenic callus was significantly higher than in non-embryogenic callus.

Somatic embryogenesis has been described in peach palm as a reliable method for its in vitro multiplication and conservation. In this study, we evaluated the possible role of arabinogalactan proteins (AGPs) during this morphogenetic pathway. The presence of Yariv reagent, a synthesized chemical antibody that specifically binds AGP molecules, affected somatic embryos and callus development rate, but no effect was observed on fresh weight increment. This substance also had profound effects on embryo morphology: somatic embryos presented loose cells in the protoderm and no signs of polarization could be observed. To better evaluate the role of AGPs, analyses of specific monoclonal antibodies (MAbs) against different AGP epitopes revealed a specific pattern of distribution for each epitope. MAb JIM13 had differential expression and showed intense signal on the embryogenic sector and some immediately adjacent layers. MAb JIM7 against pectin recognized cell walls and a specific layer over the developing somatic embryo, as well as over the shoot meristem region of mature somatic embryos. This corresponds to an extracellular matrix surface network (ECMSN) associated with the development of somatic embryos and closely related to the expression of MAb JIM13. Scanning electron microscopy confirmed the presence of an ECMSN covering a specific group of cells and ultra-structural analyses revealed that the ECMSN had lipophilic substances.

The arabinogalactan protein (AGP) fractions of embryogenic and non‐embryogenic callus lines of Euphorbia pulcherrima Willd. ex. Klotzsch were analysed over a cultivation period of 9 weeks using the β‐glucosyl Yariv reagent and an anti‐AGP antibody (LM2). The amount of AGPs detected with the Yariv reagent increased in embryogenic cultures during the development of somatic embryos. The embryogenic and non‐embryogenic callus contained different sets of AGPs characterized with the Yariv reagent and the LM2 monoclonal antibody. AGPs recognized by LM2 are localized primarily in the protodermal cells of globular somatic embryos. The development of somatic embryos of E. pulcherrima appears to be associated with the presence of particular AGPs.

The present study describes a protocol for plant regeneration via somatic embryogenesis in temporary immersion system (TIS) for Camptotheca acuminata. Somatic embryos were induced by culturing hypocotyl segments from 14-day-old in vitro grown C. acuminata seedlings in TIS. Hypocotyl segments were placed in culture vessels modified with a mechanical device to support the fixation of explants. Cultures were maintained under a 16 h photoperiod with a light intensity of 60 lmol m -2 s -1 PPF at 25 ± 1°C. After 16 weeks of incubation embryogenic calli were formed above the edge of the mechanical device in the basal Murashige and Skoog (MS) medium containing 35 g l -1 sucrose and without hormonal supplementation. For plantlet regeneration, somatic embryos at cotyledonary stage were cultured in three different concentrations of 6-benzylamino-purine (0.5, 1.0 and 1.5 mg l -1 BAP) and in plant growth regulator (PGR) free medium. In general, 0.5 mg l -1 BAP was found to be the most effective concentration for growth and development of Camptotheca embryos in TIS. Conversion of somatic embryos into plantlets was also successfully achieved on sterile substrates moistened with 0.5 mg l -1 BAP. Plantlets derived from cotyledonary embryos were rooted in vitro with 0.5 mg l -1 indole-3-butyric acid (IBA) before transfer to ex vitro conditions.

The arabinogalactan protein (AGP) fractions of embryogenic non-embryogenic callus contained different sets of AGPs charand non-embryogenic callus lines of Euphorbia pulcherrima acterized with the Yariv reagent and the LM2 mono-Willd. ex. Klotzsch were analysed over a cultivation period of clonal antibody. AGPs recognized by LM2 are localized primarily in the protodermal cells of globular somatic em-9 weeks using the -glucosyl Yariv reagent and an anti-AGP antibody (LM2). The amount of AGPs detected with the bryos. The development of somatic embryos of E. pulcherrima appears to be associated with the presence of particular Yariv reagent increased in embryogenic cultures during the development of somatic embryos. The embryogenic and AGPs.