Similarities and Differences in the GFP Movement in the Zygotic and Somatic Embryos of Arabidopsis

Intercellular signaling during embryo patterning is not well understood and the role of symplasmic communication has been poorly considered. The correlation between the symplasmic domains and the development of the embryo organs/tissues during zygotic embryogenesis has only been described for a few examples, including Arabidopsis. How this process occurs during the development of somatic embryos (SEs) is still unknown. The aim of these studies was to answer the question: do SEs have a restriction in symplasmic transport depending on the developmental stage that is similar to their zygotic counterparts? The studies included an analysis of the GFP distribution pattern as expressed under diverse promoters in zygotic embryos (ZEs) and SEs. The results of the GFP distribution in the ZEs and SEs showed that 1/the symplasmic domains between the embryo organs and tissues in the SEs was similar to those in the ZEs and 2/the restriction in symplasmic transport in the SEs was correlated with the developmental stage and was similar to the one in their zygotic counterparts, however, with the spatio-temporal differences and different PDs SEL value between these two types of embryos.

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An Arabidopsis AT-hook motif nuclear protein mediates somatic embryogenesis and coinciding genome duplication

Nature Communications ◽

10.1038/s41467-021-22815-8 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Omid Karami ◽

Arezoo Rahimi ◽

Patrick Mak ◽

Anneke Horstman ◽

Kim Boutilier ◽

...

Keyword(s):

Somatic Embryogenesis ◽

Somatic Embryos ◽

Nuclear Protein ◽

Genome Duplication ◽

Baby Boom ◽

Hormone Treatment ◽

Zygotic Embryogenesis ◽

Embryonic Cells ◽

Embryo Patterning ◽

Transcription Factor Genes

AbstractPlant somatic cells can be reprogrammed into totipotent embryonic cells that are able to form differentiated embryos in a process called somatic embryogenesis (SE), by hormone treatment or through overexpression of certain transcription factor genes, such as BABY BOOM (BBM). Here we show that overexpression of the AT-HOOK MOTIF CONTAINING NUCLEAR LOCALIZED 15 (AHL15) gene induces formation of somatic embryos on Arabidopsis thaliana seedlings in the absence of hormone treatment. During zygotic embryogenesis, AHL15 expression starts early in embryo development, and AH15 and other AHL genes are required for proper embryo patterning and development beyond the globular stage. Moreover, AHL15 and several of its homologs are upregulated and required for SE induction upon hormone treatment, and they are required for efficient BBM-induced SE as downstream targets of BBM. A significant number of plants derived from AHL15 overexpression-induced somatic embryos are polyploid. Polyploidisation occurs by endomitosis specifically during the initiation of SE, and is caused by strong heterochromatin decondensation induced by AHL15 overexpression.

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Histocytological Study of Somatic Embryogenesis in the Tree Cinnamomum camphora L. (Lauraceae)

Notulae Botanicae Horti Agrobotanici Cluj-Napoca ◽

10.15835/nbha47411655 ◽

2019 ◽

Vol 47 (4) ◽

pp. 1348-1358

Author(s):

Ruyue JING ◽

Peilan WANG ◽

Zhen HUANG ◽

Zhihui LI

Keyword(s):

Somatic Embryogenesis ◽

Somatic Embryos ◽

Single Cells ◽

Digital Object Identifier ◽

Zygotic Embryos ◽

Zygotic Embryogenesis ◽

Vascular Bundles ◽

Cinnamomum Camphora ◽

Embryogenic Calli ◽

Embryogenic Cells

Histocytological studies were conducted on primary, secondary, and malformed embryos produced during somatic embryogenesis of Cinnamomum camphora L. to better understand its development. Exploring its callus types and structures provided a theoretical basis for clarifying the mechanism of somatic embryogenesis, which may shed light on the mechanism of zygotic embryogenesis. We used immature zygotic embryos as explants to induce somatic embryos, forming many embryogenic calli that differentiated into mature somatic embryos. Our results showed that somatic embryogenesis of C. camphora was similar to that of zygotic embryos. We have been dedifferentiated four types of callus. Compared with non-embryogenic cells, embryogenic cells had a closer arrangement, larger nucleus, thicker cytoplasm, more starch granules and easier to stain into black. Somatic embryogenesis had two pathways: direct (predominate) and indirect (rare). Embryogenic cells of C. camphora could have either an internal or external origin, the latter being primary, for which occurrence sites include epidermis and near-epidermis (little internally). Mostly arising from single cells, C. camphora follows two developmental pathways: single-cell equal as opposed to unequal, wherein both divide to form multi-cell proembryos. However, multicellular origins can occasionally occur and feature physiological isolation during somatic embryo development. This development has four embryo stages: globular, heart-shaped, torpedo, and cotyledon, with procambium cells apparent in globular embryos and late cotyledons forming “Y-shaped” vascular bundles. Secondary embryos were present in all stages, directly occurring on primary embryo’s germ and radicle end surfaces. We conclude that secondary and primary embryos of C. camphora undergo similar developmental processes. At the same time, conjoined cotyledon embryos and morphological abnormal embryos were found, with an internal origin more likely to generate abnormal embryos. ********* In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 4, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue. *********

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Symplasmic Isolation Contributes to Somatic Embryo Induction and Development in the Tree Fern Cyathea delgadii Sternb

Plant and Cell Physiology ◽

10.1093/pcp/pcaa058 ◽

2020 ◽

Vol 61 (7) ◽

pp. 1273-1284

Author(s):

Małgorzata Grzyb ◽

Justyna Wróbel-Marek ◽

Ewa Kurczyńska ◽

Mirosław Sobczak ◽

Anna Mikuła

Keyword(s):

Somatic Embryo ◽

Somatic Embryos ◽

Microscopic Analysis ◽

Direct Somatic Embryogenesis ◽

Tree Fern ◽

Symplasmic Domains ◽

Symplasmic Transport ◽

Trisodium Salt ◽

Further Development ◽

Embryogenic Transition

Abstract In this report, we describe studies on symplasmic communication and cellular rearrangement during direct somatic embryogenesis (SE) in the tree fern Cyathea delgadii. We analyzed changes in the symplasmic transport of low-molecular-weight fluorochromes, such as 8-hydroxypyrene-1,3,6-trisulfonic acid, trisodium salt (HPTS) and fluorescein (delivered to cells as fluorescein diacetate, FDA), within stipe explants and somatic embryos originating from single epidermal cells and developing during 16-d long culture. Induction of SE is preceded by a restriction in fluorochrome distribution between certain explant cells. Microscopic analysis showed a series of cellular changes like a decrease in vacuole size, increase in vacuole numbers, and increased density of cytoplasm and deposition of electron-dense material in cell walls that may be related with embryogenic transition. In somatic embryos, the limited symplasmic communication between cells was observed first in linear tri-cellular embryos. Further development of the fern embryo was associated with the formation of symplasmic domains corresponding to the four segments of the plant body. Using symplasmic tracers, we provided evidence that the changes in plasmodesmata permeability are corelated with somatic-to-embryogenic transition and somatic embryo development.

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Somatic embryogenesis from immature and mature zygotic embryos and from cotyledons and needles of somatic plantlets of Larix

Canadian Journal of Forest Research ◽

10.1139/x94-015 ◽

1994 ◽

Vol 24 (1) ◽

pp. 100-106 ◽

Cited By ~ 32

Author(s):

M.A. Lelu ◽

K. Klimaszewska ◽

P.J. Charest

Keyword(s):

Somatic Embryogenesis ◽

Developmental Stage ◽

Somatic Embryos ◽

Zygotic Embryos ◽

Mature Tree ◽

Immature Zygotic Embryos ◽

Specific Combination ◽

Induction Frequency ◽

Initiation Frequency ◽

First Time

Induction of embryonal masses was achieved from full-sib immature zygotic embryos of Larixdecidua Mill., Larix × eurolepis A. Henry, and Larix × leptoeuropaea, and it was found to be affected by the developmental stage of the embryos. Furthermore, the expiant response depended on a specific combination of parental trees used for production of seeds. For the first time, induction was successful in L. decidua with mature zygotic embryos. These embryos were isolated from one of the three seedlots tested and induction frequency was 5%. Mature somatic embryos of L. × leptoeuropaea expressed an initiation frequency of 83%. Cotyledons and needles of plantlets derived from somatic embryos of L. × leptoeuropaea were used as expiants to induce somatic embryogenesis at a frequency of 8 and 3%, respectively. A cytokinin pretreatment seemed to enhance the frequency of induction. Mature somatic embryos were obtained from embryonal masses derived from expiants of different ontogenic age. Future opportunities of research into the induction of embryonal masses from mature tree tissues are discussed.

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Somatic embryogenesis in conifers

Canadian Journal of Botany ◽

10.1139/b91-237 ◽

1991 ◽

Vol 69 (9) ◽

pp. 1873-1899 ◽

Cited By ~ 154

Author(s):

T. E. Tautorus ◽

L. C. Fowke ◽

D. I. Dunstan

Keyword(s):

Somatic Embryogenesis ◽

Picea Glauca ◽

Somatic Embryos ◽

Zygotic Embryos ◽

Zygotic Embryogenesis ◽

Direct Gene Transfer ◽

Plantlet Production ◽

Substantial Progress ◽

Liquid Suspensions

Substantial progress has been made towards the development of systems for in vitro embryogenesis in conifers. Since the first report of somatic embryogenesis from zygotic embryos of Picea abies in 1985, cultured explants of at least 18 different coniferous species have been induced to produce somatic embryos. Somatic embryos have been cryopreserved, grown in liquid suspensions, and matured into plants. In addition, plantlets have been regenerated from protoplasts isolated from embryogenic suspensions of Picea glauca and Larix ×eurolepis, permitting studies into direct gene transfer and somatic hybridization. Currently however, it is only possible to obtain somatic embryogenesis from embryonic and juvenile explants. Furthermore, for most species the efficiency of plantlet production from somatic embryos is poor and remains a problem for the commercial utilization of this technology. Biochemical, cytological, and physiological studies of conifer somatic embryogenesis have resulted in improved knowledge concerning the origin of somatic embryos, storage product accumulation during embryo development, and similarities with zygotic embryos. Furthermore, the technique of indirect immunofluorescence microscopy has permitted investigations of the cytoskeleton in conifer cells and protoplasts, providing insights into cell division and morphogenesis. In this review, emphasis is placed on the more fundamental aspects of conifer somatic embryogenesis. Where possible, comparisons between zygotic and somatic embryogenesis are made. Key words: somatic embryogenesis, zygotic embryogenesis, conifers, review.

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An Arabidopsis AT-hook motif nuclear protein mediates somatic embryogenesis and coinciding genome duplication

10.1101/2020.01.03.892869 ◽

2020 ◽

Author(s):

Omid Karami ◽

Arezoo Rahimi ◽

Patrick Mak ◽

Anneke Horstman ◽

Kim Boutilier ◽

...

Keyword(s):

Somatic Embryogenesis ◽

Somatic Embryos ◽

Nuclear Protein ◽

Genome Duplication ◽

Baby Boom ◽

Hormone Treatment ◽

Zygotic Embryogenesis ◽

Embryonic Cells ◽

Embryo Patterning ◽

Transcription Factor Genes

AbstractPlant somatic cells can be reprogrammed to totipotent embryonic cells that are able to form differentiated embryos in a process called somatic embryogenesis (SE), by hormone treatment or through overexpression of certain transcription factor genes, such as BABY BOOM (BBM). Here we show that overexpression of the AT-HOOK MOTIF CONTAINING NUCLEAR LOCALIZED 15 (AHL15) gene induces formation of somatic embryos on Arabidopsis thaliana seedlings in the absence of hormone treatment. During zygotic embryogenesis, AHL15 expression starts early in embryo development, and AH15 and other AHL genes are required for proper embryo patterning and development beyond the heart stage. Moreover, AHL15 and several of its homologs are upregulated and required for SE induction upon hormone treatment, and they are required for efficient BBM-induced SE as downstream targets of BBM. A significant number of plants derived from AHL15 overexpression-induced somatic embryos are polyploid. Polyploidisation occurs by endomitosis specifically during the initiation of SE, assumingly due to AHL15-mediated heterochromatin decondensation coinciding with the acquisition of embryonic competency in somatic plant cells.

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The embryonic transcriptome of Arabidopsis thaliana

10.1101/479584 ◽

2018 ◽

Author(s):

Falko Hofmann ◽

Michael A. Schon ◽

Michael D. Nodine

Keyword(s):

Arabidopsis Thaliana ◽

Somatic Embryos ◽

Developmental Stages ◽

Zygotic Embryo ◽

Low Cost ◽

Superior Performance ◽

Zygotic Embryos ◽

Zygotic Embryogenesis ◽

Biological Processes

AbstractCellular differentiation is associated with changes in transcript populations. Accurate quantification of transcriptomes during development can thus provide global insights into differentiation processes including the fundamental specification and differentiation events operating during plant embryogenesis. However, multiple technical challenges have limited the ability to obtain high quality early embryonic transcriptomes, namely the low amount of RNA obtainable and contamination from surrounding endosperm and seed-coat tissues. We compared the performance of three low-input mRNA sequencing (mRNA-seq) library preparation kits on 0.1 to 5 nanograms (ng) of total RNA isolated from Arabidopsis thaliana (Arabidopsis) embryos and identified a low-cost method with superior performance. This mRNA-seq method was then used to profile the transcriptomes of Arabidopsis embryos across eight developmental stages. By comprehensively comparing embryonic and post-embryonic transcriptomes, we found that embryonic transcriptomes do not resemble any other plant tissue we analyzed. Moreover, transcriptome clustering analyses revealed the presence of four distinct phases of embryogenesis which are enriched in specific biological processes. We also compared zygotic embryo transcriptomes with publicly available somatic embryo transcriptomes. Strikingly, we found little resemblance between zygotic embryos and somatic embryos derived from late-staged zygotic embryos suggesting that the molecular basis of somatic and zygotic embryogenesis are distinct from each other. In addition to the biological insights gained from our systematic characterization of the Arabidopsis embryonic transcriptome, we provide a data-rich resource for the community to explore.Key MessageArabidopsis embryos possess unique transcriptomes relative to other plant tissues including somatic embryos, and can be partitioned into four transcriptional phases with characteristic biological processes.

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Spatio-temporal selection of reference genes in the two congeneric species of Glycyrrhiza

Scientific Reports ◽

10.1038/s41598-020-79298-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Yuping Li ◽

Xiaoju Liang ◽

Xuguo Zhou ◽

Yu An ◽

Ming Li ◽

...

Keyword(s):

Gene Expression ◽

Developmental Stage ◽

Reference Genes ◽

Developmental Stages ◽

Individual Factors ◽

Congeneric Species ◽

Spatio Temporal ◽

The Stability ◽

Different Tissues ◽

Selection Of

AbstractGlycyrrhiza, a genus of perennial medicinal herbs, has been traditionally used to treat human diseases, including respiratory disorders. Functional analysis of genes involved in the synthesis, accumulation, and degradation of bioactive compounds in these medicinal plants requires accurate measurement of their expression profiles. Reverse transcription quantitative real-time PCR (RT-qPCR) is a primary tool, which requires stably expressed reference genes to serve as the internal references to normalize the target gene expression. In this study, the stability of 14 candidate reference genes from the two congeneric species G. uralensis and G. inflata, including ACT, CAC, CYP, DNAJ, DREB, EF1, RAN, TIF1, TUB, UBC2, ABCC2, COPS3, CS, R3HDM2, were evaluated across different tissues and throughout various developmental stages. More importantly, we investigated the impact of interactions between tissue and developmental stage on the performance of candidate reference genes. Four algorithms, including geNorm, NormFinder, BestKeeper, and Delta Ct, were used to analyze the expression stability and RefFinder, a comprehensive software, provided the final recommendation. Based on previous research and our preliminary data, we hypothesized that internal references for spatio-temporal gene expression are different from the reference genes suited for individual factors. In G. uralensis, the top three most stable reference genes across different tissues were R3HDM2, CAC and TUB, while CAC, CYP and ABCC2 were most suited for different developmental stages. CAC is the only candidate recommended for both biotic factors, which is reflected in the stability ranking for the spatio (tissue)-temporal (developmental stage) interactions (CAC, R3HDM2 and DNAJ). Similarly, in G. inflata, COPS3, R3HDM2 and DREB were selected for tissues, while RAN, COPS3 and CS were recommended for developmental stages. For the tissue-developmental stage interactions, COPS3, DREB and ABCC2 were the most suited reference genes. In both species, only one of the top three candidates was shared between the individual factors and their interactions, specifically, CAC in G. uralensis and COPS3 in G. inflata, which supports our overarching hypothesis. In summary, spatio-temporal selection of reference genes not only lays the foundation for functional genomics research in Glycyrrhiza, but also facilitates these traditional medicinal herbs to reach/maximize their pharmaceutical potential.

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Seed storage proteins in developing somatic embryos of alfalfa: defects in accumulation compared to zygotic embryos

Journal of Experimental Botany ◽

10.1093/jxb/45.6.699 ◽

1994 ◽

Vol 45 (6) ◽

pp. 699-708 ◽

Cited By ~ 19

Author(s):

Joan E. Krochko ◽

David J. Bantroch ◽

John S. Greenwood ◽

J. Derek Bewley

Keyword(s):

Somatic Embryos ◽

Storage Proteins ◽

Seed Storage ◽

Seed Storage Proteins ◽

Zygotic Embryos

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Induction of Somatic Embryogenesis in Vulnerable Medicinal Plant Hedychium spicatum Buch-Ham ex Smith

Plant Tissue Culture and Biotechnology ◽

10.3329/ptcb.v23i2.17506 ◽

2014 ◽

Vol 23 (2) ◽

pp. 147-155 ◽

Cited By ~ 1

Author(s):

Dinesh Giri ◽

Sushma Tamta

Keyword(s):

Somatic Embryogenesis ◽

Medicinal Plant ◽

Somatic Embryos ◽

Synthetic Seeds ◽

Ex Situ ◽

Secondary Embryogenesis ◽

Zygotic Embryos ◽

High Concentration ◽

Cotyledon Explants ◽

Short Period

This protocol has been developed for somatic embryogenesis in Hedychium spicatum. Simultaneously, a method has also been developed for the production of synthetic seeds by using somatic embryos. Direct somatic embryos were developed on cotyledon explants of zygotic embryos on MS supplemented with high concentration of NAA (20.0 µM). Induction of secondary embryogenesis was best in 2,4-D supplemented medium fortified with activated charcoal. Germination of somatic embryos was enhanced by using GA3. Besides this, round and semi-hard beads of somatic embryos (synthetic seeds) could be produced by using 2% Na-alginate and 100 mM calcium chloride and more than 30% germination of synthetic seeds was achieved in MS. Well acclimated plants produced via somatic embryogenesis and/or synthetic seeds were transferred to field where more than 60% survived. This simple study enabled us to obtain a number of plantlets throughout the year each cycle requiring a short period of time. Besides propagation, this study provided an ex situ method for conservation of this vulnerable Himalayan species.D. O. I.http://dx.doi.org/10.3329/ptcb.v23i2.17506Plant Tissue Cult. & Biotech. 23(2): 147-155, 2013 (December)

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