Editing Gibberellin (section)

===Biosynthesis===
Gibberellins are usually synthesized from the [[methylerythritol phosphate]] (MEP) pathway in higher plants.<ref name="Hedden-2012">{{cite journal | vauthors = Hedden P, Thomas SG | s2cid = 25627726 | title = Gibberellin biosynthesis and its regulation | journal = The Biochemical Journal | volume = 444 | issue = 1 | pages = 11–25 | date = May 2012 | pmid = 22533671 | doi = 10.1042/BJ20120245 }}</ref> In this pathway, bioactive GA is produced from [[trans-geranylgeranyl diphosphate|''trans''-geranylgeranyl diphosphate]] (GGDP), with the participation of three classes of enzymes: terpene syntheses (TPSs), [[Cytochrome P450 monooxygenase system|cytochrome P450 monooxygenases]] (P450s), and [[2-oxoglutarate–dependent dioxygenase]]s (2ODDs).<ref name="Hedden-2012" /><ref name="Yamaguchi-2008" /> The MEP pathway follows eight steps:<ref name="Yamaguchi-2008" />

# GGDP is converted to ent-copalyl diphosphate (ent-CDP) by [[ent-copalyl diphosphate synthase|''ent''-copalyl diphosphate synthase]] (CPS)
# ent-CDP is converted to ent-kaurene by [[ent-kaurene synthase|''ent''-kaurene synthase]] (KS)
# ent-kaurene is converted to ent-kaurenol by [[ent-kaurene oxidase|''ent''-kaurene oxidase]] (KO)
# ent-kaurenol is converted to ent-kaurenal by KO
# ent-kaurenal is converted to ent-kaurenoic acid by KO
# [[ent-kaurenoic acid]] is converted to ent-7a-hydroxykaurenoic acid by [[ent-kaurenoic acid oxidase|''ent''-kaurenoic acid oxidase]] (KAO)
# ent-7a-hydroxykaurenoic acid is converted to GA12-aldehyde by KAO
# GA12-aldehyde is converted to GA12 by KAO. GA12 is processed to the bioactive GA4 by oxidations on C-20 and C-3, which is accomplished by 2 soluble ODDs: GA 20-oxidase and GA 3-oxidase.

One or two genes encode the enzymes responsible for the first steps of GA biosynthesis in ''[[Arabidopsis]]'' and rice.<ref name="Yamaguchi-2008" /> The null alleles of the genes encoding CPS, KS, and KO result in GA-deficient ''Arabidopsis'' dwarves.<ref>{{cite journal | vauthors = Koornneef M, van der Veen JH | title = Induction and analysis of gibberellin sensitive mutants in Arabidopsis thaliana (L.) heynh | journal = Theoretical and Applied Genetics | volume = 58 | issue = 6 | pages = 257–63 | date = November 1980 | pmid = 24301503 | doi = 10.1007/BF00265176 | s2cid = 22824299 }}</ref> Multigene families encode the 2ODDs that catalyze the formation of GA<sub>12</sub> to bioactive GA<sub>4</sub>.<ref name="Yamaguchi-2008" />

AtGA3ox1 and AtGA3ox2, two of the four genes that encode GA3ox in ''Arabidopsis'', affect vegetative development.<ref>{{cite journal | vauthors = Mitchum MG, Yamaguchi S, Hanada A, Kuwahara A, Yoshioka Y, Kato T, Tabata S, Kamiya Y, Sun TP | title = Distinct and overlapping roles of two gibberellin 3-oxidases in Arabidopsis development | journal = The Plant Journal | volume = 45 | issue = 5 | pages = 804–18 | date = March 2006 | pmid = 16460513 | doi = 10.1111/j.1365-313X.2005.02642.x | doi-access = free }}</ref> Environmental stimuli regulate AtGA3ox1 and AtGA3ox2 activity during seed germination.<ref name="Yamaguchi-1998">{{cite journal | vauthors = Yamaguchi S, Smith MW, Brown RG, Kamiya Y, Sun T | title = Phytochrome regulation and differential expression of gibberellin 3beta-hydroxylase genes in germinating Arabidopsis seeds | journal = The Plant Cell | volume = 10 | issue = 12 | pages = 2115–26 | date = December 1998 | pmid = 9836749 | pmc = 143973 | doi = 10.1105/tpc.10.12.2115 }}</ref><ref name="Yamauchi-2004">{{cite journal | vauthors = Yamauchi Y, Ogawa M, Kuwahara A, Hanada A, Kamiya Y, Yamaguchi S | title = Activation of gibberellin biosynthesis and response pathways by low temperature during imbibition of Arabidopsis thaliana seeds | journal = The Plant Cell | volume = 16 | issue = 2 | pages = 367–78 | date = February 2004 | pmid = 14729916 | pmc = 341910 | doi = 10.1105/tpc.018143 }}</ref> In ''Arabidopsis'', GA20ox overexpression leads to an increase in GA concentration.<ref>{{cite journal | vauthors = Coles JP, Phillips AL, Croker SJ, García-Lepe R, Lewis MJ, Hedden P | title = Modification of gibberellin production and plant development in Arabidopsis by sense and antisense expression of gibberellin 20-oxidase genes | journal = The Plant Journal | volume = 17 | issue = 5 | pages = 547–56 | date = March 1999 | pmid = 10205907 | doi = 10.1046/j.1365-313X.1999.00410.x }}</ref><ref>{{cite journal | vauthors = Huang S, Raman AS, Ream JE, Fujiwara H, Cerny RE, Brown SM | title = Overexpression of 20-oxidase confers a gibberellin-overproduction phenotype in Arabidopsis | journal = Plant Physiology | volume = 118 | issue = 3 | pages = 773–81 | date = November 1998 | pmid = 9808721 | pmc = 34787 | doi = 10.1104/pp.118.3.773 }}</ref>

====Sites of biosynthesis====
Most bioactive Gibberellins are located in actively growing organs on plants.<ref name="Hedden-2012" /> Both GA20ox and GA3ox genes (genes coding for GA 20-oxidase and GA 3-oxidase) and the SLENDER1 gene (a GA [[signal transduction]] gene) are found in growing organs on rice, which suggests bioactive GA synthesis occurs at their site of action in growing organs in plants.<ref name="Kaneko-2003">{{cite journal | vauthors = Kaneko M, Itoh H, Inukai Y, Sakamoto T, Ueguchi-Tanaka M, Ashikari M, Matsuoka M | title = Where do gibberellin biosynthesis and gibberellin signaling occur in rice plants? | journal = The Plant Journal | volume = 35 | issue = 1 | pages = 104–15 | date = July 2003 | pmid = 12834406 | doi = 10.1046/j.1365-313X.2003.01780.x | doi-access = free }}</ref> During flower development, the tapetum of anthers is believed to be a primary site of GA biosynthesis.<ref name="Kaneko-2003" /><ref>{{cite journal | vauthors = Itoh H, Tanaka-Ueguchi M, Kawaide H, Chen X, Kamiya Y, Matsuoka M | title = The gene encoding tobacco gibberellin 3beta-hydroxylase is expressed at the site of GA action during stem elongation and flower organ development | journal = The Plant Journal | volume = 20 | issue = 1 | pages = 15–24 | date = October 1999 | pmid = 10571861 | doi = 10.1046/j.1365-313X.1999.00568.x | doi-access = free }}</ref>

====Differences between biosynthesis in fungi and lower plants====
The flower ''Arabidopsis'' and the fungus ''[[Gibberella fujikuroi]]'' possess different GA pathways and enzymes.<ref name="Yamaguchi-2008" /> P450s in fungi perform functions analogous to the functions of KAOs in plants.<ref>{{cite journal | vauthors = Rojas MC, Hedden P, Gaskin P, Tudzynski B | title = The P450-1 gene of Gibberella fujikuroi encodes a multifunctional enzyme in gibberellin biosynthesis | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 98 | issue = 10 | pages = 5838–43 | date = May 2001 | pmid = 11320210 | pmc = 33300 | doi = 10.1073/pnas.091096298 | bibcode = 2001PNAS...98.5838R | doi-access = free }}</ref> The function of CPS and KS in plants is performed by a single enzyme in fungi (CPS/KS).<ref>{{cite journal | vauthors = Kawaide H, Imai R, Sassa T, Kamiya Y | title = Ent-kaurene synthase from the fungus Phaeosphaeria sp. L487. cDNA isolation, characterization, and bacterial expression of a bifunctional diterpene cyclase in fungal gibberellin biosynthesis | journal = The Journal of Biological Chemistry | volume = 272 | issue = 35 | pages = 21706–12 | date = August 1997 | pmid = 9268298 | doi = 10.1074/jbc.272.35.21706 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Toyomasu T, Kawaide H, Ishizaki A, Shinoda S, Otsuka M, Mitsuhashi W, Sassa T | title = Cloning of a full-length cDNA encoding ent-kaurene synthase from Gibberella fujikuroi: functional analysis of a bifunctional diterpene cyclase | journal = Bioscience, Biotechnology, and Biochemistry | volume = 64 | issue = 3 | pages = 660–4 | date = March 2000 | pmid = 10803977 | doi = 10.1271/bbb.64.660 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Tudzynski B, Kawaide H, Kamiya Y | title = Gibberellin biosynthesis in Gibberella fujikuroi: cloning and characterization of the copalyl diphosphate synthase gene | journal = Current Genetics | volume = 34 | issue = 3 | pages = 234–40 | date = September 1998 | pmid = 9745028 | doi = 10.1007/s002940050392 | s2cid = 3021994 }}</ref> In plants the Gibberellin biosynthesis genes are found randomly on multiple chromosomes, but in fungi are found on one chromosome
.<ref>{{cite journal | vauthors = Hedden P, Phillips AL, Rojas MC, Carrera E, Tudzynski B | title = Gibberellin Biosynthesis in Plants and Fungi: A Case of Convergent Evolution? | journal = Journal of Plant Growth Regulation | volume = 20 | issue = 4 | pages = 319–331 | date = December 2001 | pmid = 11986758 | doi = 10.1007/s003440010037 | s2cid = 25623658 }}</ref><ref>{{cite journal | vauthors = Kawaide H | title = Biochemical and molecular analyses of gibberellin biosynthesis in fungi | journal = Bioscience, Biotechnology, and Biochemistry | volume = 70 | issue = 3 | pages = 583–90 | date = March 2006 | pmid = 16556972 | doi = 10.1271/bbb.70.583 | s2cid = 20952424 | doi-access = free }}</ref> 

Plants produce low amount of Gibberellic Acid, therefore is produced for industrial purposes by microorganisms. Industrially GA<sub>3</sub> can be produced by submerged fermentation, but this process presents low yield with high production costs and hence higher sale value, nevertheless other alternative process to reduce costs of its production is [[solid-state fermentation]] (SSF) that allows the use of agro-industrial residues.<ref>{{cite journal | vauthors = Lopes AL, Silva DN, Rodrigues C, Costa JL, Machado MP, Penha RO, Biasi LA, Ricardo C | title = Gibberellic acid fermented extract obtained by solid-state fermentation using citric pulp by Fusarium moniliforme: Influence on Lavandula angustifolia Mill. cultivated in vitro | journal = Pak J Bot. | year = 2013 | volume = 45 | pages = 2057–2064 }}</ref>