In Norway spruce, as in many other conifers, the germination capacity of somatic embryos is strongly influenced by the desiccation phase inserted after maturation. The intensity of drying during desiccation eminently affected the formation of emblings (i.e., seedlings developed from somatic embryos). Compared to non-desiccated embryos, the germination capacity of embryos desiccated at 100% relative humidity was about three times higher, but the reduction of relative humidity to 95% and 90% had a negative effect on the subsequent embryo development.
Tags: Norway spruce
Desiccation as a post-maturation treatment helps complete maturation of Norway spruce somatic embryos: carbohydrates, phytohormones and proteomic status
Exposure of Norway spruce (Picea abies) somatic embryos and those of many other conifers to post-maturation desiccation treatment significantly improves their germination. An integration analysis was conducted to understand the underlying processes induced during the desiccation phase at the molecular level. Carbohydrate, protein and phytohormone assays associated with histological and proteomic studies were performed for the evaluation of markers and actors in this phase.
Autophagy is an evolutionary conserved catabolic process deemed to maintain or restore cellular and organismal homeostasis. In plants, basal autophagy is essential for growth and development, it is required for nutrient remobilization during senescence and nutrient deficiency, for removal of organelles and macromolecules formed during plant development or damaged by environmental stresses.
In summary, the exposure of Norway spruce EC to UV-B radiation at different stages of maturation had the strongest effect on cell viability of embryos at early stages of development and resulted in the inhibition of somatic embryo development and/or the substantial decrease in the number of embryos. The extent of cell damage was dependent on the UV-B dose applied, as well as the embryo developmental stage, and might be related to differentiation of the outermost cell layers and formation of protoderm.
Conifer somatic embryogenesis (SE) is a process driven by exogenously supplied plant growth regulators (PGRs). Exogenous PGRs and endogenous phytohormones trigger particular ontogenetic events. Complex mechanisms involving a number of endogenous phytohormones control the differentiation of cells and tissues, as well as the establishment of structures and organs. Most of the mechanisms and hormonal functions in the SE of conifers have not yet been described.
Polyamines putrescine (Put), spermidine (Spd), and spermine (Spm) are ubiquitous, small aliphatic polycations found in eukaryotic organisms, which regulate vital developmental and physiological events. They play an important role in diverse plant growth and developmental processes and adaptation to environmental stresses. Among other functions, spermidine stimulates the process of autophagy across species including yeast, animals, and even humans.
Somatic embryogenic culture can be induced from immature zygotic embryos extirped from seeds in the course of summer.
Quantification of histochemical detection of polyphenolic compounds in somatic embryos of Norway spruce
Under standard cultivation conditions, Norway spruce somatic embryos (SEs) accumulate polyphenolic compounds mostly in the root cap. In response to UV-B, the accumulation of polyphenolics increases in protodermal cells and subprotodermal cortical cells and idioblasts in hypocotyl and cotyledons where they can attenuate UV-B stress. To quantify polyphenolic compounds accumulated in somatic embryos on the histological level resin sections were prepared, stained with Toluidine Blue.
Somatic embryogenesis is a developmental process where a plant somatic cell dedifferentiate to a totipotent embryonic stem cell that has the ability to give rise to an embryo under appropriate conditions. Desiccation is the final phase of normal embryonic development in most angiosperms and appears to be important in the transition from embryogeny to the ability to germinate and form normal seedlings.
It is necessary to find convenient and measurable criteria for the evaluation of seeds/embryos quality before germination because of a long time interval between the preparation of seeds or embryos (before germination) and obtaining the seedlings or emblings. The success of all treatments before germination is assessed by the quality of the newly formed plants only.