Stoma — разлика између измена

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Stome su manje ako je njihov broj veći i obrnuto. Na njihov broj, veličinu, oblik i raspored u listu mogu da utiču ekološki činioci kao na primer:vlažnost staništa, mineralna ishrana, temperatura, svetlost. Položaj stoma prvenstveno zavisi od vlažnosti staništa. Kod većine biljaka one se nalaze u nivou epidermisa. Kod biljaka koje žive na suvim staništima stome su uvučene čime se smanjuje translacija.
Stome su manje ako je njihov broj veći i obrnuto. Na njihov broj, veličinu, oblik i raspored u listu mogu da utiču ekološki činioci kao na primer:vlažnost staništa, mineralna ishrana, temperatura, svetlost. Položaj stoma prvenstveno zavisi od vlažnosti staništa. Kod većine biljaka one se nalaze u nivou epidermisa. Kod biljaka koje žive na suvim staništima stome su uvučene čime se smanjuje translacija.

== Evolucija ==
{{rut}}
[[File:Tomato stoma observed through immersion oil.gif|thumb|Tomato stoma observed through immersion oil]]
There is little evidence of the evolution of stomata in the fossil record, but they had appeared in land plants by the middle of the Silurian period.<ref>{{Cite journal
| last1 = D. Edwards | first1 = H. Kerp
| last2 = Hass | first2 = H.
| year = 1998
| title = Stomata in early land plants: an anatomical and ecophysiological approach
| journal = Journal of Experimental Botany
| volume = 49
| pages = 255–278
| doi = 10.1093/jxb/49.Special_Issue.255
| issue = Special Issue
| doi-access = free
}}</ref> They may have evolved by the modification of [[conceptacles]] from plants' alga-like ancestors.<ref>{{cite book
| last = Krassilov | first = Valentin A.
| chapter = Macroevolutionary events and the origin of higher taxa
| pages=265–289
| chapter-url=https://books.google.com/books?id=tJeZC885-OcC&pg=PA265
| isbn = 978-1-4020-1693-6
| editor-first = Solomon P.
| editor-last= Wasser
| year = 2004
| publisher = Kluwer Acad. Publ.
| location = Dordrecht
| title = Evolutionary theory and processes : modern horizons : papers in honour of Eviatar Nevo }}</ref>
However, the evolution of stomata must have happened at the same time as the waxy [[Plant cuticle|cuticle]] was evolving&nbsp;– these two traits together constituted a major advantage for early terrestrial plants.

== Razviće ==

There are three major epidermal cell types which all ultimately derive from the outermost (L1) tissue layer of the [[shoot apical meristem]], called protodermal cells: [[trichome]]s, [[pavement cells]] and guard cells, all of which are arranged in a non-random fashion.

An asymmetrical cell division occurs in protodermal cells resulting in one large cell that is fated to become a pavement cell and a smaller cell called a meristemoid that will eventually differentiate into the guard cells that surround a stoma. This meristemoid then divides asymmetrically one to three times before differentiating into a guard mother cell. The guard mother cell then makes one symmetrical division, which forms a pair of guard cells.<ref name=":6">{{Cite journal|last1=Bergmann|first1=Dominique C.; Lukowitz, Wolfgang; Somerville, Chris R.|last2=Lukowitz|first2=W|last3=Somerville|first3=CR|date=4 July 2004|title=Stomatal Development and Pattern Controlled by a MAPKK Kinase|url=http://www.sciencemag.org/cgi/content/ful/304/5676/1494/DC1|journal=Science|volume=304|issue=5676|pages=1494–1497|doi=10.1126/science.1096014|pmid=15178800|bibcode=2004Sci...304.1494B|s2cid=32009729}}</ref> Cell division is inhibited in some cells so there is always at least one cell between stomata.<ref name=":7">{{Cite journal|last1=Pillitteri|first1=Lynn Jo|last2=Dong|first2=Juan|date=2013-06-06|title=Stomatal Development in Arabidopsis|journal=The Arabidopsis Book / American Society of Plant Biologists|volume=11|page=e0162|doi=10.1199/tab.0162|issn=1543-8120|pmc=3711358|pmid=23864836}}</ref>

Stomatal patterning is controlled by the interaction of many [[signal transduction]] components such as ''EPF'' (Epidermal Patterning Factor), ''ERL'' (ERecta Like) and ''YODA'' (a putative [[MAP kinase kinase kinase]]).<ref name=":7" /> Mutations in any one of the genes which encode these factors may alter the development of stomata in the epidermis.<ref name=":7" /> For example, a mutation in one gene causes more stomata that are clustered together, hence is called Too Many Mouths (''TMM'').<ref name=":6" /> Whereas, disruption of the ''SPCH'' (SPeecCHless) gene prevents stomatal development all together.<ref name=":7" /> &nbsp;Activation of stomatal production can occur by the activation of EPF1, which activates TMM/ERL, which together activate YODA. YODA inhibits SPCH, causing SPCH activity to decrease, allowing for asymmetrical cell division that initiates stomata formation.<ref name=":7" /><ref>{{Cite journal|last1=Casson|first1=Stuart A|last2=Hetherington|first2=Alistair M|date=2010-02-01|title=Environmental regulation of stomatal development|journal=Current Opinion in Plant Biology|volume=13|issue=1|pages=90–95|doi=10.1016/j.pbi.2009.08.005|pmid=19781980}}</ref> Stomatal development is also coordinated by the cellular peptide signal called stomagen, which signals the inhibition of the SPCH, resulting in increased number of stomata.<ref>{{Cite journal|last1=Sugano|first1=Shigeo S.|last2=Shimada|first2=Tomoo|last3=Imai|first3=Yu|last4=Okawa|first4=Katsuya|last5=Tamai|first5=Atsushi|last6=Mori|first6=Masashi|last7=Hara-Nishimura|first7=Ikuko|date=2010-01-14|title=Stomagen positively regulates stomatal density in Arabidopsis|journal=Nature|language=en|volume=463|issue=7278|pages=241–244|doi=10.1038/nature08682|pmid=20010603|issn=0028-0836|bibcode=2010Natur.463..241S|hdl=2433/91250|s2cid=4302041|hdl-access=free}}</ref>

Environmental and hormonal factors can affect stomatal development. Light increases stomatal development in plants; while, plants grown in the dark have a lower amount of stomata. [[Auxin]] represses stomatal development by affecting their development at the receptor level like the ERL and TMM receptors. However, a low concentration of auxin allows for equal division of a guard mother cell and increases the chance of producing guard cells.<ref>{{cite journal | last1 = Balcerowicz | first1 = M. | last2 = Ranjan | first2 = A. | last3 = Rupprecht | first3 = L. | last4 = Fiene | first4 = G. | last5 = Hoecker | first5 = U. | year = 2014 | title = Auxin represses stomatal development in dark-grown seedling via Aux/IAA proteins | journal = Development | volume = 141 | issue = 16| pages = 3165–3176 | doi=10.1242/dev.109181| pmid = 25063454 | doi-access = free }}</ref>

Most [[angiosperm trees]] have stomata only on their lower leaf surface. [[Populus|Poplars]] and [[willows]] have them on both surfaces. When leaves develop stomata on both leaf surfaces, the stomata on the lower surface tend to be larger and more numerous, but there can be a great degree of variation in size and frequency about species and genotypes. [[Fraxinus americana|White ash]] and [[white birch]] leaves had fewer stomata but larger in size. On the other hand [[sugar maple]] and [[silver maple]] had small stomata that were more numerous.<ref>{{cite book |last1=Pallardy |first1=Stephen |title=Physiology of Woody Plants |page=14}}</ref>


== Vidi još ==
== Vidi još ==
Ред 73: Ред 113:
* Poljoprivredna botanika (1975) Univerzitet u Novom Sadu.
* Poljoprivredna botanika (1975) Univerzitet u Novom Sadu.
* {{Cite book| ref=harv|last=Esau| first=K. |year=1977 | title=Anatomy of Seed Plants | url=https://archive.org/details/anatomyofseedpla00esau| publisher=Wiley and Sons |isbn=978-0-471-24520-9 |pages=[https://archive.org/details/anatomyofseedpla00esau/page/88 88]}}
* {{Cite book| ref=harv|last=Esau| first=K. |year=1977 | title=Anatomy of Seed Plants | url=https://archive.org/details/anatomyofseedpla00esau| publisher=Wiley and Sons |isbn=978-0-471-24520-9 |pages=[https://archive.org/details/anatomyofseedpla00esau/page/88 88]}}
* {{Cite journal|last=Kinoshita|first=Toshinori|last2=Emi|first2=Takashi|last3=Tominaga|first3=Misumi|last4=Sakamoto|first4=Koji|last5=Shigenaga|first5=Ayako|last6=Doi|first6=Michio|last7=Shimazaki|first7=Ken-ichiro|date=2003-12-01|title=Blue-Light- and Phosphorylation-Dependent Binding of a 14-3-3 Protein to Phototropins in Stomatal Guard Cells of Broad Bean|journal=Plant Physiology|volume=133|issue=4|pages=1453–1463|doi=10.1104/pp.103.029629|issn=0032-0889|pmid=14605223|pmc=300702}}
* {{Cite journal|last=Shimazaki|first=Ken-ichiro|last2=Doi|first2=Michio|last3=Assmann|first3=Sarah M.|last4=Kinoshita|first4=Toshinori|date=2007|title=Light Regulation of Stomatal Movement|journal=Annual Review of Plant Biology|volume=58|issue=1|pages=219–247|doi=10.1146/annurev.arplant.57.032905.105434|pmid=17209798}}
* {{Cite journal|last=Kinoshita|first=Toshinori|last2=Shimazaki|first2=Ken-ichiro|date=2002-11-15|title=Biochemical Evidence for the Requirement of 14-3-3 Protein Binding in Activation of the Guard-cell Plasma Membrane H+-ATPase by Blue Light|journal=Plant and Cell Physiology|volume=43|issue=11|pages=1359–1365|doi=10.1093/pcp/pcf167|pmid=12461136|issn=1471-9053|doi-access=free}}

{{refend}}
{{refend}}



Верзија на датум 28. фебруар 2023. у 03:25

Stoma na listu paradajza
Poprečni presek stome
Donja strana lista. Kod ove vrste (Tradescantia zebrina) stoma izgleda zeleno (usled hlorofila).

Stome (od grčke rečki στόμα, „usta”)[1] sitni su otvori na naličju lista koji služe za vršenje transpiracije i respiracije.[2] Kroz stome voda isparava i iznose se štetne materije iz organizma. Zbog specijalne građe stominog aparata stoma može da se otvori i zatvori po potrebi.

Pore su ograničene parom specijalizovanih parenhimskih ćelija poznatih kao ćelije zatvaračice, koje su odgovorne za regulisanje veličine otvora. Ovaj termin se takođe koristi za kolektivno imenovanje celokupnog stomalnog kompleksa, samih pora i pratećih ćelija zatvaračica.[3] Vazduh koji sadrži ugljen-dioksid i kiseonik se unosi u biljku kroz ove otvore i koristi u fotosintezi u mezofilnim ćelijama (parenhimskim ćelijama sa hloroplastima) i respiraciji. Kiseonik koji se formira kao nusproizvod fotosinteze, difuzijom izlazi u atmosferu kroz iste otvore.

Stome su prisutne u sporofitnoj generaciji svih grupa kopnenih biljki izuzev jetrenjača. Kod vaskularnih biljki broj, veličina i distribucija stoma široko varira. Dikotiledone biljke obično imaju više stoma na donjoj površini lista nego na gornjoj površini. Monokotiledone biljke kao što su crni luk, ovas i kukuruz mogu da imaju aproksimativno isti broj stoma na obe strane lista.[4] Kod biljaka sa plutajućim lišćem, stome se mogu naći samo na gornjem epidermisu, a potopljeni listovi mogu da uopšte nemaju stome. Većina vrsta drveća ima stome samo na donjoj strani lišća.[5] Lišće sa stomama na obe strane se nazva amfistomatno lišće; lišće sa stomama samo na donjoj strani je hipostomatno, i lišće sa stomama samo na gornjoj površini je epistomatno ili hiperstomatno.[5] Veličina varira među vrstama, sa dužinom od kraja do kraja od 10 do 80 µm i širinom u opsegu od nekoliko do 50 µm.[6]

Građa stominog aparata

Sastoji se od:

  • Dve ćelije zatvaračice koje grade stomin otvor,sadrže hloroplaste,
  • pomoćnih ćelija,
  • stomine duplja  i
  • susednih ćelija.

Zidovi ćelija zatvaračica su neravnomerno zadebljali,a promenom oblika,ćelije zatvaračice otvaraju ili zatvaraju stomin otvor. Stomine ćelije uvek idu po dve zajedno,okrenute su jedna drugoj izdubljenim stranama i na taj način grade stomin otvor. Ovim se reguliše promet gasova i odavanje vodene pare (translacija). Ispod otvora se nalazi Stomina duplja.

Ćelije epidermisa koje se naslanjaju na leđne strane ćelija zatvaračica nazivaju se pomoćnice. Ćelije Hlorenhima (parenhima za fotosintezu) nazivaju se susedne. Sve ove ćelije zajedno (zatvaračice, pomoćnice i susedne ćelije) čine stomin aparat.

Uloga stominog aparata

Osnovne funkcije stominog aparata su izmena gasova i regulacija transpiracije. Stoma ima najviše na listovima, ali se mogu nalaziti i na stablu,cvetovima i plodovima. Količina vode koju listovi odaju u jedinici vremena iznosi svega oko jedne trećine vode koja isparava pri istoj temperaturi sa iste slobodne vodene površine. Otvorene stome zauzimaju u proseku oko 1% (od 0,5 do 3,5%) od ukupne površine lista,iz čega sledi da voda oko trideset puta brže difunduje kroz pore stoma nego sa slobodne vodene površine.

Molekuli vode koji se nalaze blizu ruba pore stome brže isparavaju od molekula koji se nalaze u sredini pore. Razlog tome je što je  vazduh koji se nalazi iznad srednjeg dela pore zasićeniji vodenom parom,nego iznad rubnog dela.   Ovo se naziva rubnim efektom. Što je manja površina isparavanja toliko je veći rubni efekat,a isparena količina vode sve je proporcionalnija sa prečnikom stoma,a sve manja sa površinom Rubni efekat ne dolazi do izražaja u svim uslovima.

Mehanizam otvaranja i zatvaranja stominog aparata

Za pokrete stoma od velikog su značaja su vodeni i osmotski pritisak  ćelija zatvaračica.

Da bi voda ušla u ćelije zatvaračice i izazvala otvaranje stoma potrebno je da vodeni potencijal ćelija bude niži ,negativniji nego potencijal sredine.Vodeni potencijal ćelija zatvaračica u velikoj meri zavisi od  osmotskog pritiska, to jest turgora u njima.

U novije vreme pokreti ćelija zatvaračica dovode se u vezu sa nakupljanjem jona. U toku dana,pri Sunčevoj svetlosti kada su stome otvorene dolazi do nakupljanja kalijuma i natrijuma. Joni se u toku otvaranja stoma transportuju u ćelije zatvaračice iz okolnih ćelija preko plazmodezmi.

U mraku,kalijumova pumpa ne funkcioniše ,a nagomilani joni se pasivno ili aktivno izlučuju preko membrane.

Važna uloga u mehanizmu otvaranja i zatvaranja stoma prepisuje se i fiziološki aktivnim materijama posebno abscisionoj kiselini. Ova kiselina inhibira nakupljanje katjona u ćelijama zatvaračicama i podstiče njihov izlazak iz njih. Na ovaj način abscisiona kiselina prouzrokuje zatvaranje stoma.

U mehanizmu otvaranja i zatvaranja stoma veliku ulogu  ima i građa stoma.  Strana ćelije zatvaračice koja je okrenuta stominom otvoru je zadebljala ,a suprotna leđna je tanja.

Kada turgor u ćelijama  zatvaračicama raste dolazi do istezanja tanjeg leđnog dela ćelijskog zida . On privlači deblji trbušni deo ćelijskog zida i stoma se otvara. Ovaj tip stoma je rasprostranjen u većine monokotiledonih i dikotiledonih  biljaka.

Smanjenjem turgora ćelijski zidovi se vraćaju u svoj prvobitan položaj i stoma se zatvara.

Otvorena i zatvorena stoma # Epidermalna ćelija # Ćelija pratilica # Stoma # K+ joni # Voda # Vakuola

Zatvaranje stoma može biti hidroaktivno i hidropasivno.

Mehanizam stomine ćelije.

Hidroaktivno zatvaranje se dešava kada nema svetlosti  i u slučaju nedostatka vode.

Do hidropasivnog zatvaranja dolazi kada epidermalne ćelije koje okružuju stomu usled kvašenja bubre. One se bubrenjem šire i vrše pritisak na ćelije zatvaračice,usled čega se stome zatvore. Na pokrete ćelija zatvaračica stoma utiču i brojni ekološki faktori (temperatura,vlažnost sredine,koncentracija CO2, nedostatak vode, osvetljenost). 

Stome su uglavnom potpuno otvorene u jutarnjim časovima,kada je turgescentnost listova najveća,a kako dan odmiče i bliži se sutonu,otvori stoma se postepeno smanjuju.

Broj i položaj stominh aparata

Broj stoma po jedinici površine lista je različit i specifičan za pojedine vrste, zavisi od mnogo faktora, kao što su veličina lista,topografije i starosti lista. Na 1 mm² lisne površine,njihov broj, u proseku,se kreće od 100 do 300,a može može biti znatno manji ili veći,od 10 do 1000.

Stome su manje ako je njihov broj veći i obrnuto. Na njihov broj, veličinu, oblik i raspored u listu mogu da utiču ekološki činioci kao na primer:vlažnost staništa, mineralna ishrana, temperatura, svetlost. Položaj stoma prvenstveno zavisi od vlažnosti staništa. Kod većine biljaka one se nalaze u nivou epidermisa. Kod biljaka koje žive na suvim staništima stome su uvučene čime se smanjuje translacija.

Evolucija

Tomato stoma observed through immersion oil

There is little evidence of the evolution of stomata in the fossil record, but they had appeared in land plants by the middle of the Silurian period.[7] They may have evolved by the modification of conceptacles from plants' alga-like ancestors.[8] However, the evolution of stomata must have happened at the same time as the waxy cuticle was evolving – these two traits together constituted a major advantage for early terrestrial plants.

Razviće

There are three major epidermal cell types which all ultimately derive from the outermost (L1) tissue layer of the shoot apical meristem, called protodermal cells: trichomes, pavement cells and guard cells, all of which are arranged in a non-random fashion.

An asymmetrical cell division occurs in protodermal cells resulting in one large cell that is fated to become a pavement cell and a smaller cell called a meristemoid that will eventually differentiate into the guard cells that surround a stoma. This meristemoid then divides asymmetrically one to three times before differentiating into a guard mother cell. The guard mother cell then makes one symmetrical division, which forms a pair of guard cells.[9] Cell division is inhibited in some cells so there is always at least one cell between stomata.[10]

Stomatal patterning is controlled by the interaction of many signal transduction components such as EPF (Epidermal Patterning Factor), ERL (ERecta Like) and YODA (a putative MAP kinase kinase kinase).[10] Mutations in any one of the genes which encode these factors may alter the development of stomata in the epidermis.[10] For example, a mutation in one gene causes more stomata that are clustered together, hence is called Too Many Mouths (TMM).[9] Whereas, disruption of the SPCH (SPeecCHless) gene prevents stomatal development all together.[10]  Activation of stomatal production can occur by the activation of EPF1, which activates TMM/ERL, which together activate YODA. YODA inhibits SPCH, causing SPCH activity to decrease, allowing for asymmetrical cell division that initiates stomata formation.[10][11] Stomatal development is also coordinated by the cellular peptide signal called stomagen, which signals the inhibition of the SPCH, resulting in increased number of stomata.[12]

Environmental and hormonal factors can affect stomatal development. Light increases stomatal development in plants; while, plants grown in the dark have a lower amount of stomata. Auxin represses stomatal development by affecting their development at the receptor level like the ERL and TMM receptors. However, a low concentration of auxin allows for equal division of a guard mother cell and increases the chance of producing guard cells.[13]

Most angiosperm trees have stomata only on their lower leaf surface. Poplars and willows have them on both surfaces. When leaves develop stomata on both leaf surfaces, the stomata on the lower surface tend to be larger and more numerous, but there can be a great degree of variation in size and frequency about species and genotypes. White ash and white birch leaves had fewer stomata but larger in size. On the other hand sugar maple and silver maple had small stomata that were more numerous.[14]

Vidi još

Reference

  1. ^ στόμα. Liddell, Henry George; Scott, Robert; A Greek–English Lexicon at the Perseus Project
  2. ^ „Living Environment—Regents High school examination” (PDF). January 2011 Regents. NYSED. Приступљено 15. 06. 2013. 
  3. ^ Esau 1977, стр. 88
  4. ^ Weyers, J. D. B.; Meidner, H. (1990). Methods in stomatal research. Longman Group UK Ltd. стр. 5. ISBN 978-0-582-03483-9. 
  5. ^ а б Willmer & Fricker 1996, стр. 16
  6. ^ Fricker, M.; Willmer, C. (2012). Stomata. Springer Netherlands. стр. 18. ISBN 978-94-011-0579-8. Приступљено 15. 06. 2016. 
  7. ^ D. Edwards, H. Kerp; Hass, H. (1998). „Stomata in early land plants: an anatomical and ecophysiological approach”. Journal of Experimental Botany. 49 (Special Issue): 255—278. doi:10.1093/jxb/49.Special_Issue.255Слободан приступ. 
  8. ^ Krassilov, Valentin A. (2004). „Macroevolutionary events and the origin of higher taxa”. Ур.: Wasser, Solomon P. Evolutionary theory and processes : modern horizons : papers in honour of Eviatar Nevo. Dordrecht: Kluwer Acad. Publ. стр. 265—289. ISBN 978-1-4020-1693-6. 
  9. ^ а б Bergmann, Dominique C.; Lukowitz, Wolfgang; Somerville, Chris R.; Lukowitz, W; Somerville, CR (4. 7. 2004). „Stomatal Development and Pattern Controlled by a MAPKK Kinase”. Science. 304 (5676): 1494—1497. Bibcode:2004Sci...304.1494B. PMID 15178800. S2CID 32009729. doi:10.1126/science.1096014. 
  10. ^ а б в г д Pillitteri, Lynn Jo; Dong, Juan (2013-06-06). „Stomatal Development in Arabidopsis”. The Arabidopsis Book / American Society of Plant Biologists. 11: e0162. ISSN 1543-8120. PMC 3711358Слободан приступ. PMID 23864836. doi:10.1199/tab.0162. 
  11. ^ Casson, Stuart A; Hetherington, Alistair M (2010-02-01). „Environmental regulation of stomatal development”. Current Opinion in Plant Biology. 13 (1): 90—95. PMID 19781980. doi:10.1016/j.pbi.2009.08.005. 
  12. ^ Sugano, Shigeo S.; Shimada, Tomoo; Imai, Yu; Okawa, Katsuya; Tamai, Atsushi; Mori, Masashi; Hara-Nishimura, Ikuko (2010-01-14). „Stomagen positively regulates stomatal density in Arabidopsis”. Nature (на језику: енглески). 463 (7278): 241—244. Bibcode:2010Natur.463..241S. ISSN 0028-0836. PMID 20010603. S2CID 4302041. doi:10.1038/nature08682. hdl:2433/91250Слободан приступ. 
  13. ^ Balcerowicz, M.; Ranjan, A.; Rupprecht, L.; Fiene, G.; Hoecker, U. (2014). „Auxin represses stomatal development in dark-grown seedling via Aux/IAA proteins”. Development. 141 (16): 3165—3176. PMID 25063454. doi:10.1242/dev.109181Слободан приступ. 
  14. ^ Pallardy, Stephen. Physiology of Woody Plants. стр. 14. 

Literatura

Spoljašnje veze