Plant embryonic development

2025-10-18T20:59:07Z

2600:4040:51B8:5000:D966:B8BC:45EE:B70A: Removed superfluous comma.

{{Short description|Process after the fertilization of an ovule to produce a fully developed plant embryo}}
'''Plant embryonic development''', also '''plant embryogenesis''', is a process that occurs after the [[Fertilisation|fertilization]] of an [[ovule]] to produce a fully developed plant [[embryo]]. This is a pertinent stage in the plant life cycle that is followed by [[dormancy]] and [[germination]].<ref name=Mr.Yuttana>{{Cite journal|last1=Goldberg|first1=Robert|last2=Paiva|first2=Genaro|last3=Yadegari|first3=Ramin|title=Plant Embryogenesis: Zygote to Seed|journal=Science|date=October 28, 1994|volume=266|issue=5185|pages=605–614|doi=10.1126/science.266.5185.605|pmid=17793455|bibcode=1994Sci...266..605G|s2cid=5959508}}</ref> The [[zygote]] produced after fertilization must undergo various cellular divisions and differentiations to become a mature embryo.<ref name="Mr.Yuttana" /> An end stage embryo has five major components including the shoot apical [[meristem]], [[hypocotyl]], root meristem, [[root cap]], and [[cotyledon]]s.<ref name="Mr.Yuttana" /> Unlike the [[embryonic development]] in animals, and specifically in [[human embryonic development|humans]], plant embryonic development results in an immature form of the plant, lacking most structures like leaves, stems, and reproductive structures.<ref name=":1">{{Cite journal|last=Jurgens|first=Gerd|date=May 19, 1995|title=Axis formation in plant embryogenesis: cues and clues|journal=Cell|volume=81|issue=4|pages=467–470|doi=10.1016/0092-8674(95)90065-9|pmid=7758100|s2cid=17143479|doi-access=free}}</ref> However, both plants and animals including humans, pass through a [[phylotypic stage]] that evolved independently<ref>{{Cite journal|last1=Drost|first1=Hajk-Georg|last2=Janitza|first2=Philipp |last3=Grosse |first3=Ivo |last4=Quint |first4=Marcel | year=2017|title=Cross-kingdom comparison of the developmental hourglass|journal=Current Opinion in Genetics & Development|volume=45|pages=69–75|doi=10.1016/j.gde.2017.03.003|pmid=28347942|doi-access=free}}</ref> and that causes a developmental constraint limiting morphological diversification.<ref>{{Cite journal|last1=Irie|first1=Naoki|last2=Kuratani|first2=Shigeru|date=2011-03-22|title=Comparative transcriptome analysis reveals vertebrate phylotypic period during organogenesis|journal=Nature Communications|language=en|volume=2|doi=10.1038/ncomms1248|issn=2041-1723|pmc=3109953|pmid=21427719|article-number=248|bibcode=2011NatCo...2..248I}}</ref><ref>{{Cite journal|last1=Domazet-Lošo|first1=Tomislav|last2=Tautz|first2=Diethard|date=2010-12-09|title=A phylogenetically based transcriptome age index mirrors ontogenetic divergence patterns|journal=Nature|language=en|volume=468|issue=7325|pages=815–818|doi=10.1038/nature09632|issn=0028-0836|pmid=21150997|bibcode=2010Natur.468..815D|s2cid=1417664}}</ref><ref>{{Cite journal|last1=Quint|first1=Marcel|last2=Drost|first2=Hajk-Georg|last3=Gabel|first3=Alexander|last4=Ullrich|first4=Kristian Karsten|last5=Bönn|first5=Markus|last6=Grosse|first6=Ivo|date=2012-10-04|title=A transcriptomic hourglass in plant embryogenesis|journal=Nature|language=en|volume=490|issue=7418|pages=98–101|doi=10.1038/nature11394|pmid=22951968|bibcode=2012Natur.490...98Q|s2cid=4404460|issn=0028-0836}}</ref><ref>{{Cite journal|last1=Drost|first1=Hajk-Georg|last2=Gabel|first2=Alexander|last3=Grosse|first3=Ivo|last4=Quint|first4=Marcel|date=2015-05-01|title=Evidence for Active Maintenance of Phylotranscriptomic Hourglass Patterns in Animal and Plant Embryogenesis|url= |journal=Molecular Biology and Evolution|language=en|volume=32|issue=5|pages=1221–1231|doi=10.1093/molbev/msv012|issn=0737-4038|pmc=4408408|pmid=25631928}}</ref>

== Morphogenesis in eudicots == 

[[Embryogenesis]] in [[Eudicots|eudicot]] angiosperms occurs naturally as a result of single, or [[double fertilization]], of the ovule, giving rise to two distinct structures: the plant embryo and the [[endosperm]] which go on to develop into a seed. The zygote undergoes a series of cellular differentiations and divisions to produce a mature embryo. These morphogenic events form the basic cellular pattern necessary for the development of the shoot-root axis and the primary tissue layers. They also initiates the formation of meristematic regions.<ref name=":6">{{Cite journal |last1=Radoeva |first1=Tatyana |last2=Weijers |first2=Dolf |date=November 2014 |title=A roadmap to embryo identity in plants |journal=Trends in Plant Science |volume=19 |issue=11 |pages=709–716 |doi=10.1016/j.tplants.2014.06.009 |pmid=25017700 |bibcode=2014TPS....19..709R }}</ref>

[[File:Seed Development Cycle.svg|thumb|309x309px|Six moments in embryogenesis
{|
|-
| {{Ordered list |list_style_type=upper-roman |Two cell stage |Eight cell stage |Globular stage |Heart stage |Torpedo stage |Maturation }}
|| {{Ordered list |list_style_type=decimal |endosperm |single celled zygote |embryo |suspensor |cotyledons |shoot apical meristem (SAM) |root apical meristem (RAM) }}
|}
]]
[[File:Capsella bursa-pastoris, kiembol (Hanstein).jpg|thumb|309px|Closer look at the early embryo]]

=== Plant ===

Following fertilization, the zygote and endosperm are present within the ovule, as shown in stage I of the illustration on this page. The zygote subsequently undergoes an asymmetric transverse [[cell division]], producing to two distinct cells - a small apical cell positioned above a large basal cell.<ref name=":3">{{Cite journal|last1=West|first1=Marilyn A. L.|last2=Harada|first2=John J.|author-link2=John Harada|date=October 1993|title=Embryogenesis in Higher Plants: An Overview|journal=The Plant Cell|volume=5|issue=10|pages=1361–1369|doi=10.2307/3869788|pmid=12271035|pmc=160368|jstor=3869788 |bibcode=1993PlanC...5.1361W }}</ref><ref name="plant_dev">{{cite book |last1=Peris |first1=Cristina I. Llavanta |last2=Rademacher |first2=Eike H. |last3=Weijers |first3=Dolf |editor1-last=Timmermans |editor1-first=Marja C. P. |title=Plant development |date=2010 |publisher=Academic Press (imprint of Elsevier) |location=San Diego, CA |isbn=978-0-12-380910-0 |pages=1–27 |edition=1st |language=en |chapter=Chapter 1 Green Beginnings - Pattern Formation in the Early Plant Embryo}}</ref>
These cells differ in structure and function and give rise to distinct embryonic components thereby establishing [[Cell polarity|polarity]] in the developing embryo.
;apical cell:The apical cell, at the top, retains most of the [[cytoplasm]] from the original zygote.<ref name=":22">{{Cite journal|last1=Souter|first1=Martin|last2=Lindsey|first2=Keith|date=June 2000|title=Polarity and signaling in plant embryogenesis|journal=Journal of Experimental Botany|volume=51|issue=347|pages=971–983|doi=10.1093/jexbot/51.347.971|pmid=10948225|doi-access=free}}</ref> It gives rise to the '''hypocotyl''', '''shoot apical meristem''', and '''cotyledons'''.<ref name=":22"/>
;basal cell:The basal cell, below the apical cell, contains a large [[vacuole]]<ref name=":22"/> and gives rise to the '''hypophysis'''<ref name=":3" /> and the [[Suspensor#Plants|'''suspensor''']].<ref name=":3" />

=== Eight cell stage ===

After two rounds of longitudinal division and one round of transverse division, an eight-celled embryo is formed.<ref name=":103">{{Cite book|title=Raven Biology of Plants|last1=Evert|first1=Ray F.|last2=Eichhorn|first2=Susan E.|publisher=W. H. Freeman and Company|year=2013|location=New York|pages=526–530}}</ref> Stage II in the illustration above shows the embryo at this eight cell stage. According to Laux et al., four distinct domains are present at this stage.<ref name=":8">{{Cite journal|last1=Laux|first1=T.|last2=Wurschum|first2=T.|last3=Breuninger|first3=Holger|title=Genetic Regulation of Embryonic Pattern Formation|journal=The Plant Cell|year=2004|volume=6|issue=Suppl |pages=190–202|doi=10.1105/tpc.016014|pmid=15100395|pmc=2643395 |bibcode=2004PlanC..16S.190L }}</ref> The first two domains contribute to the embryo proper. The ''apical embryo domain'', gives rise to the shoot apical meristem and cotyledons. The second domain, the ''central embryo domain'', gives rise to the hypocotyl, root apical meristem, and parts of the cotyledons. The ''basal embryo domain form the third domain and contains'' the hypophysis. Which will later give rise to the radicle and the root cap. The final domain, the ''suspensor'', is located at the base of the embryo and connect it to the endosperm, facilitating nutrient transfer.<ref name=":0" />

=== Sixteen cell stage ===

Additional cell divisions occur, which leads to the sixteen cell stage. The four domains are still present, but they are more defined with the presence of more cells. The important aspect of this stage is the introduction of the protoderm, which is meristematic tissue that will give rise to the epidermis.<ref name=":103" /> The protoderm is the outermost layer of cells in the embryo proper.<ref name=":103" />

=== Globular stage ===

The name of this stage is indicative of the embryo's appearance at this point in embryogenesis; it is spherical or globular. Stage III, in the photograph above, depicts what the embryo looks like during the globular stage. 1 is indicating the location of the endosperm. The important component of the globular phase is the introduction of the rest of the primary meristematic tissue. The protoderm was already introduced during the sixteen cell stage. According to Evert and Eichhorn, the ground meristem and procambium are initiated during the globular stage.<ref name=":103" /> The ground meristem will go on to form the [[ground tissue]], which includes the pith and cortex. The procambium will eventually form the [[vascular tissue]], which includes the xylem and [[phloem]].<ref>{{Cite journal |last1=Armenta-Medina |first1=Alma |last2=Gillmor |first2=C. Stewart |last3=Gao |first3=Peng |last4=Mora-Macias |first4=Javier |last5=Kochian |first5=Leon V. |last6=Xiang |first6=Daoquan |last7=Datla |first7=Raju |date=2021-01-11 |title=Developmental and genomic architecture of plant embryogenesis: from model plant to crops |journal=Plant Communications |volume=2 |issue=1 |article-number=100136 |doi=10.1016/j.xplc.2020.100136 |pmid=33511346 |pmc=7816075 |bibcode=2021PlCom...200136A |issn=2590-3462}}</ref>

=== Heart stage ===
[[File:Embryo (PSF).png|thumb|Cotyledon location]]
According to Evert and Eichhorn, the heart stage is a transition period where the cotyledons finally start to form and elongate.<ref name=":103" /> It is given this name in eudicots because most plants from this group have two cotyledons, giving the embryo a heart shaped appearance. The shoot apical meristem is between the cotyledons. Stage IV, in the illustration above, indicates what the embryo looks like at this point in development. 5 indicates the position of the cotyledons.<ref name="Hugo A 2019">{{Cite journal |last1=Méndez-Hernández |first1=Hugo A. |last2=Ledezma-Rodríguez |first2=Maharshi |last3=Avilez-Montalvo |first3=Randy N. |last4=Juárez-Gómez |first4=Yary L. |last5=Skeete |first5=Analesa |last6=Avilez-Montalvo |first6=Johny |last7=De-la-Peña |first7=Clelia |last8=Loyola-Vargas |first8=Víctor M. |date=2019 |title=Signaling Overview of Plant Somatic Embryogenesis |journal=Frontiers in Plant Science |volume=10 |article-number=77 |doi=10.3389/fpls.2019.00077 |doi-access=free |issn=1664-462X |pmc=6375091 |pmid=30792725 |bibcode=2019FrPS...10...77M }}</ref>

=== Proembryo stage ===

The [https://pubmed.ncbi.nlm.nih.gov/24226374/ '''proembryo''' stage] is defined by the continued growth of the cotyledons and axis elongation.<ref name=":103" /> In addition, programmed cell death must occur during this stage. This is carried out throughout the entire growth process, like any other development.<ref name=":7">{{Cite journal|last1=Bozhkov|first1=P. V.|last2=Filonova|first2=L. H.|last3=Suarez|first3=M. F.|date=January 2005|title=Programmed cell death in plant embryogenesis|journal=Current Topics in Developmental Biology|volume=67|pages=135–179|doi=10.1016/S0070-2153(05)67004-4|pmid=15949533|isbn=978-0-12-153167-6}}</ref> However, in the torpedo stage of development, parts of the suspensor complex must be terminated.<ref name=":7" /> The suspensor complex is shortened because at this point in development most of the nutrition from the endosperm has been utilized, and there must be space for the mature embryo.<ref name=":22"/> After the suspensor complex is gone, the embryo is fully developed.<ref name=":8" /> Stage V, in the illustration above, indicates what the embryo looks like at this point in development.<ref>{{Cite journal |last1=Smith |first1=D. L. |last2=Krikorian |first2=A. D. |date=June 1990 |title=Somatic proembryo production from excised, wounded zygotic carrot embryos on hormone-free medium: evaluation of the effects of pH, ethylene and activated charcoal |journal=Plant Cell Reports |volume=9 |issue=1 |pages=34–37 |doi=10.1007/BF00232131 |issn=0721-7714 |pmid=24226374 |bibcode=1990PCelR...932131S }}</ref>

=== Maturation ===

The second phase, or postembryonic development, involves the maturation of cells, which involves cell growth and the storage of macromolecules (such as oils, starches and proteins) required as a 'food and energy supply' during [[germination]] and seedling growth. In this stage, the seed coat hardens to help protect the embryo and store available nutrients.<ref>{{Cite book|last=Raven|first=Peter H.|title=Biology of Plants; Fourth Edition|publisher=Worth Publishers, INC.|year=1986|isbn=0-87901-315-X|location=United States of America|page=379|language=English}}</ref> The appearance of a mature embryo is seen in Stage VI, in the illustration above.

== Dormancy ==
The end of embryogenesis is defined by an arrested development phase, or stop in growth. This phase usually coincides with a necessary component of growth called [[dormancy]]. Dormancy is a period in which a seed cannot germinate, even under optimal environmental conditions, until a specific requirement is met.<ref>{{Cite journal|last1=Baskin|first1=Jeremy M.|last2=Baskin|first2=Carol C.|date=2004|title=A classification system for seed dormancy|url=https://www.cambridge.org/core/services/aop-cambridge-core/content/view/024181C2EEE1FC55B9D7578660A5CB66/S0960258504000017a.pdf/classification_system_for_seed_dormancy.pdf|journal=Seed Science Research|volume=14|issue=1 |pages=1–16|via=Google Scholar|doi=10.1079/SSR2003150|bibcode=2004SeeSR..14....1B |doi-access=free|access-date=2018-04-17|archive-date=2019-02-13|archive-url=https://web.archive.org/web/20190213123719/https://www.cambridge.org/core/services/aop-cambridge-core/content/view/024181C2EEE1FC55B9D7578660A5CB66/S0960258504000017a.pdf/classification_system_for_seed_dormancy.pdf|url-status=live}}</ref> Breaking dormancy, or finding the specific requirement of the seed, can be rather difficult. For example, a seed coat can be extremely thick. According to Evert and Eichhorn, very thick seed coats must undergo a process called scarification, in order to deteriorate the coating.<ref name=":103"/> In other cases, seeds must experience stratification. This process exposes the seed to certain environmental conditions, like cold or smoke, to break dormancy and initiate germination.<ref>{{Cite journal |last=Nilsson |first=Ove |date=2022-06-20 |title=Winter dormancy in trees |journal=Current Biology |volume=32 |issue=12 |pages=R630–R634 |doi=10.1016/j.cub.2022.04.011 |issn=1879-0445 |pmid=35728543 |bibcode=2022CBio...32.R630N }}</ref>

== The role of auxin ==

[[Auxin]] is a hormone related to the elongation and regulation of plants.<ref name=":4">{{Cite journal|last1=Liu|first1=C|last2=Xu|first2=Z|last3=Chua|first3=N|title=Auxin Polar Transport Is Essential for the Establishment of Bilateral Symmetry during Early Plant Embryogenesis.|journal=The Plant Cell|volume=5|issue=6|pages=621–630|doi=10.2307/3869805|pmid=12271078|pmc=160300|jstor=3869805|year=1993|bibcode=1993PlanC...5..621L}}</ref> It also plays an important role in the establishment polarity with the plant embryo. Research has shown that the hypocotyl from both gymnosperms and angiosperms show auxin transport to the root end of the embryo.<ref name=":5">{{Cite journal|last1=Cooke|first1=T. J.|last2=Racusen|first2=R. H.|last3=Cohen|first3=J. D.|date=November 1993|title=The role of auxin in plant embryogenesis|journal=Plant Cell|volume=11|issue=11|pages=1494–1495|pmid=12271044|doi=10.1105/tpc.5.11.1494|pmc=160380}}</ref> They hypothesized that the embryonic pattern is regulated by the auxin transport mechanism and the polar positioning of cells within the ovule. The importance of auxin was shown, in their research, when carrot embryos, at different stages, were subjected to auxin transport inhibitors. The inhibitors that these carrots were subjected to made them unable to progress to later stages of embryogenesis. During the globular stage of embryogenesis, the embryos continued spherical expansion. In addition, oblong embryos continued axial growth, without the introduction of cotyledons. During the heart embryo stage of development, there were additional growth axes on hypocotyls. Further auxin transport inhibition research, conducted on ''Brassica juncea'', shows that after germination, the cotyledons were fused and not two separate structures.<ref>{{cite journal |last1=Hadfi |first1=K. |last2=Speth |first2=V. |last3=Neuhaus |first3=G. |title=Auxin-induced developmental patterns in Brassica juncea embryos |journal=Development |date=1998 |volume=125 |issue=5 |pages=879–87 |doi=10.1242/dev.125.5.879 |pmid=9449670}}</ref>

== Alternative forms of embryogenesis ==

=== Somatic embryogenesis ===
Somatic embryos are formed from plant cells that are not normally involved in the development of embryos, i.e. ordinary plant tissue. No endosperm or seed coat is formed around a somatic embryo. Applications of this process include: clonal propagation of genetically uniform plant material; elimination of viruses; provision of source tissue for genetic transformation; generation of whole plants from single cells called [[protoplast]]s; development of synthetic seed technology. Cells derived from competent source tissue are cultured to form an undifferentiated mass of cells called a [[Callus (cell biology)|callus]]. [[Plant growth regulators]] in the tissue culture medium can be manipulated to induce callus formation and subsequently changed to induce embryos to form the callus. The ratio of different [[plant growth regulators]] required to induce callus or embryo formation varies with the type of plant. Asymmetrical cell division also seems to be important in the development of somatic embryos, and while failure to form the suspensor cell is lethal to zygotic embryos, it is not lethal for somatic embryos.<ref name="Hugo A 2019"/>

=== Androgenesis ===
The process of androgenesis allows a mature plant embryo to form from a reduced, or immature, [[pollen]] grain.<ref name=":9">{{Cite journal|last1=Maraschin|first1=S. F.|last2=de Priester|first2=W.|last3=Spaink|first3=H. P.|last4=Wang|first4=M.|date=July 2005|title=Androgenic switch: an example of plant embryogenesis from the male gametophyte perspective|journal=Journal of Experimental Botany|volume=56|issue=417|pages=1711–1726|doi=10.1093/jxb/eri190|pmid=15928015|doi-access=free|hdl=1887/3665652|hdl-access=free}}</ref> Androgenesis usually occurs under stressful conditions.<ref name=":9" /> Embryos that result from this mechanism can germinate into fully functional plants. As mentioned, the embryo results from a single pollen grain. Pollen grains consists of three cells - one vegetative cell containing two generative cells. According to Maraschin et al., androgenesis must be triggered during the asymmetric division of microspores.<ref name=":9" /> However, once the vegetative cell starts to make starch and proteins, androgenesis can no longer occur. Maraschin et al., indicates that this mode of embryogenesis consists of three phases. The first phase is the ''acquisition of embryonic potential'', which is the repression of gametophyte formation, so that the differentiation of cells can occur. Then during the ''initiation of cell divisions'', multicellular structures begin to form, which are contained by the exine wall. The last step of androgenesis is ''pattern formation'', where the embryo-like structures are released out of the exile wall, in order for pattern formation to continue.<ref name=":9" />

After these three phases occur, the rest of the process falls in line with the standard embryogenesis events.<ref name=":9" />

==Plant growth and buds==
Embryonic tissue is made up of actively growing [[Cell (biology)|cells]] and the term is normally used to describe the early formation of tissue in the first stages of growth. It can refer to different stages of the [[sporophyte]] and [[gametophyte]] plant; including the growth of embryos in seedlings, and to meristematic tissues,<ref>Pandey, Brahma Prakash. 2005. Textbook of botany angiosperms: taxonomy, anatomy, embryology (including tissue culture) and economic botany. New Delhi: S. Chand & Company. p 410.</ref> which are in a persistently embryonic state,<ref>McManus, Michael T., and Bruce E. Veit. 2002. Meristematic tissues in plant growth and development. Sheffield: Sheffield Academic Press.</ref> to the growth of new buds on stems.<ref>Singh, Gurcharan. 2004. Plant systematics: an integrated approach. Enfield, NH: Science Publishers. p 61.</ref>

In both [[gymnosperm]]s and [[angiosperm]]s, the young plant contained in the seed, begins as a developing egg-cell formed after [[fertilization]] (sometimes without fertilization in a process called [[apomixis]]) and becomes a plant embryo.
This embryonic condition also occurs in the [[bud]]s that form on [[plant stem|stem]]s. The buds have tissue that has differentiated but not grown into complete structures. They can be in a resting state, lying dormant over winter or when conditions are dry, and then commence growth when conditions become suitable. Before they start growing into stem, leaves, or flowers, the buds are said to be in an embryonic state.<ref name=":0">{{Cite journal |last1=Dante |first1=Ricardo A. |last2=Larkins |first2=Brian A. |last3=Sabelli |first3=Paolo A. |date=2014 |title=Cell cycle control and seed development |journal=Frontiers in Plant Science |volume=5 |page=493 |doi=10.3389/fpls.2014.00493 |doi-access=free |issn=1664-462X |pmc=4171995 |pmid=25295050 |bibcode=2014FrPS....5..493D }}</ref>

== References ==

{{reflist}}

==External links==
{{wiktionary|hypophysis}}

{{DEFAULTSORT:Plant Embryogenesis}}
[[Category:Embryology]]
[[Category:Plant reproduction|Embryogenesis]]

Vero - Wikipedia - User contributions [en]

Plant embryonic development