Callose
{{short description|Plant cell wall polysaccharide}}
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| ImageFile = Callose.svg
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| OtherNames = (1→3)-β-D-Glucan
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| CASNo = 9064-51-1
| ChEBI = 37671
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| Section2 = {{Chembox Properties
| Formula = (C6H10O5)n
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Callose is a plant polysaccharide. Its production is due to the glucan synthase-like gene (GLS) in various places within a plant. It is produced to act as a temporary cell wall in response to stimuli such as stress or damage.{{cite book | date = 2016 | chapter = Callose | veditors = Hine R, Martin E | title = A Dictionary of Biology | publisher = Oxford University Press | isbn = 978-0-19-871437-8 | chapter-url = http://www.oxfordreference.com/view/10.1093/acref/9780198714378.001.0001/acref-9780198714378-e-6562 }} Callose is composed of glucose residues linked together through β-1,3-linkages, and is termed a β-glucan. It is thought to be manufactured at the cell wall by callose synthases and is degraded by β-1,3-glucanases. Callose is very important for the permeability of plasmodesmata (Pd) in plants; the plant's permeability is regulated by plasmodesmata callose (PDC). PDC is made by callose synthases and broken down by β-1,3-glucanases (BGs). The amount of callose that is built up at the plasmodesmatal neck, which is brought about by the interference of callose synthases (CalSs) and β-1,3-glucanases, determines the conductivity of the plasmodesmata.{{cite journal | vauthors = De Storme N, Geelen D | title = Callose homeostasis at plasmodesmata: molecular regulators and developmental relevance | journal = Frontiers in Plant Science | volume = 5 | pages = 138 | date = 2014 | pmid = 24795733 | pmc = 4001042 | doi = 10.3389/fpls.2014.00138 | doi-access = free }}
Formation and function
Callose is laid down at plasmodesmata, at the cell plate during cytokinesis, and during pollen development. Endothecium contains a substance callose, which makes it thicker. Callose is produced in response to wounding, infection by pathogens,{{cite journal | last1 = Nowicki | first1 = Marcin | last2 = Lichocka | first2 = Małgorzata | last3 =Nowakowska | first3 = Marzena | last4 = Kłosińska | first4 = Urszula | last5 = Kozik | first5 = Elżbieta U. | name-list-style = vanc | title = A Simple Dual Stain for Detailed Investigations of Plant-Fungal Pathogen Interactions | journal = Vegetable Crops Research Bulletin | date = January 2012 | volume = 77 | issue = 1 | pages = 61–74 | doi = 10.2478/v10032-012-0016-z | doi-access = free }} aluminium, and abscisic acid. When there is wounding in the plant tissue, it is fixed by the deposition of callose at the plasmodesmata and cell wall; this process happens within minutes after damage. Even though callose is not a constitutional component of the plant's cell wall, it is related to the plant's defense mechanism.{{cite journal | vauthors = Chen XY, Kim JY | title = Callose synthesis in higher plants | journal = Plant Signaling & Behavior | volume = 4 | issue = 6 | pages = 489–92 | date = June 2009 | pmid = 19816126 | pmc = 2688293 | doi=10.4161/psb.4.6.8359}} Deposits often appear on the sieve plates at the end of the growing season.{{cite book|last1=Hemsley|first1=Alan R.|last2=Bell|first2=Peter R. | name-list-style = vanc |title=Green plants : their origin and diversity|date=2000|publisher=Cambridge University Press|location=Cambridge|isbn=978-0-521-64109-8|edition=2nd}} Callose also forms immediately around the developing meiocytes and tetrads of sexually reproducing angiosperms but is not found in related apomictic taxa.{{cite journal|last1=Carman|first1=John G.|last2=Crane|first2=Charles F.|last3=Riera-Lizarazu|first3=Oscar | name-list-style = vanc |title=Comparative Histology of Cell Walls during Meiotic and Apomeiotic Megasporogenesis in Two Hexaploid Australasian Elymus Species|journal=Crop Science | date = 1991 | volume = 31 | issue = 6 | pages = 1527 | doi = 10.2135/cropsci1991.0011183X003100060029x }} Callose deposition at the cell wall has been suggested as an early marker for direct somatic embryogenesis from cortical and epidermal cells of Cichorium hybrids.{{cite journal | vauthors = Dubois T, Guedira M, Dubois J, Vasseur J | title =Direct Somatic Embryogenesis in Roots of Cichorium: Is Callose an Early Marker?|journal=Annals of Botany|date=May 1990|volume=65|issue=5|pages=539–545|doi=10.1093/oxfordjournals.aob.a087967}} Temporary callose walls are also thought to be a barrier between a cell and its environment, while the cell is undergoing a genetic programming that allows it to differentiate.{{cite journal | vauthors = Tucker MR, Paech NA, Willemse MT, Koltunow AM | date = 2001 | title = Dynamics of callose deposition and β-1,3-glucanase expression during reproductive events in sexual and apomictic Hieracium. | journal = Planta | volume = 212 | issue = 4 | pages = 487–498 | doi = 10.1007/s004250000445 | pmid = 11525505 | s2cid = 12073031 }} This is because callose walls can be found around nucellar embryos during Nucellar embryony.{{cite journal | vauthors = Gupta P, Shivanna KR, Mohan Ram HY | date = 1996 | title = Apomixis and polyembryony in the guggul plant, Commiphora wightii. | journal = Ann Bot | volume = 78 | pages = 67–72 | doi = 10.1006/anbo.1996.0097 | doi-access = }}
See also
References
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