Abscisic acid

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Abscisic acid
Stereo, skeletal formula of abscisic acid
Identifiers
Abbreviations ABA
CAS number 21293-29-8 YesY
PubChem 5280896
ChemSpider 4444418 YesY
EC number 244-319-5
MeSH Abscisic+Acid
ChEBI CHEBI:2635 N
ChEMBL CHEMBL288040 YesY
RTECS number RZ2475100
Beilstein Reference 2698956
3DMet B00898
Jmol-3D images Image 1
Properties
Molecular formula C15H20O4
Molar mass 264.32 g mol−1
Appearance Colorless crystals
Density 1.193 g/mL
Melting point 163 °C (325 °F; 436 K)[2]
Boiling point 458.7 °C (857.7 °F; 731.8 K)[3] sublimes
log P 1.896
Acidity (pKa) 4.868
Basicity (pKb) 9.129
Hazards
S-phrases S22, S24/25
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

Abscisic acid (ABA), also known as abscisin II and dormin, is a plant hormone. ABA functions in many plant developmental processes, including bud dormancy. It is degraded by the enzyme (+)-abscisic acid 8'-hydroxylase into phaseic acid.

Function[edit]

ABA was originally believed to be involved in abscission. This is now known to be the case only in a small number of plants. ABA-mediated signaling also plays an important part in plant responses to environmental stress and plant pathogens.[4][5] The plant genes for ABA biosynthesis and sequence of the pathway have been elucidated.[6][7] ABA is also produced by some plant pathogenic fungi via a biosynthetic route different from ABA biosynthesis in plants.[8]

Abscisic acid owes its names to its role in the abscission of plant leaves. In preparation for winter, ABA is produced in terminal buds.[citation needed] This slows plant growth and directs leaf primordia to develop scales to protect the dormant buds during the cold season. ABA also inhibits the division of cells in the vascular cambium, adjusting to cold conditions in the winter by suspending primary and secondary growth.[citation needed]

Abscisic acid is also produced in the roots in response to decreased soil water potential and other situations in which the plant may be under stress. ABA then translocates to the leaves, where it rapidly alters the osmotic potential of stomatal guard cells, causing them to shrink and stomata to close. The ABA-induced stomatal closure reduces transpiration, thus preventing further water loss from the leaves in times of low water availability. A close linear correlation was found between the ABA content of the leaves and their conductance (stomatal resistance) on a leaf area basis.[9]

Seed germination is inhibited by ABA in antagonism with gibberellin. ABA also prevents loss of seed dormancy.[citation needed]

Several ABA-mutant Arabidopsis thaliana plants have been identified and are available from the Nottingham Arabidopsis Stock Centre - both those deficient in ABA production and those with altered sensitivity to its action. Plants that are hypersensitive or insensitive to ABA show phenotypes in seed dormancy, germination, stomatal regulation, and some mutants show stunted growth and brown/yellow leaves. These mutants reflect the importance of ABA in seed germination and early embryo development.[citation needed]

Pyrabactin (a pyridyl containing ABA activator) is a naphthalene sulfonamide hypocotyl cell expansion inhibitor, which is an agonist of the seed ABA signaling pathway.[10] It is the first agonist of the ABA pathway that is not structurally related to ABA.[citation needed]

Biosynthesis[edit]

Abscisic acid (ABA) is an isoprenoid plant hormone, which is synthesized in the plastidal 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway; unlike the structurally related sesquiterpenes, which are formed from the mevalonic acid-derived precursor farnesyl diphosphate (FDP), the C15 backbone of ABA is formed after cleavage of C40 carotenoids in MEP. Zeaxanthin is the first committed ABA precursor; a series of enzyme-catalyzed epoxidations and isomerizations via violaxanthin, and final cleavage of the C40 carotenoid by a dioxygenation reaction yields the proximal ABA precursor, xanthoxin, which is then further oxidized to ABA.[6]

Abamine has been designed, synthesized, developed and then patented as the first specific ABA biosynthesis inhibitor, which makes it possible to regulate endogenous level of ABA.[11]

Catabolism[edit]

ABA can be catabolized to phaseic acid via AtCYP707A{1,2,3,4} (a group of P450 enzymes) or inactivated by glucose conjugation (ABA-glucose ester) via the enzyme AOG. Catabolism via the CYP707As is very important for ABA homeostasis, and mutants in those genes generally accumulate higher levels of ABA than lines overexpressing ABA biosynthetic genes.[12] In soil bacteria, an alternative catabolic pathway leading to dehydrovomifoliol via the enzyme vomifoliol dehydrogenase has been reported.

Location and timing of ABA biosynthesis[edit]

  • Released during desiccation of the vegetative tissues and when roots encounter soil compaction.[13]
  • Synthesized in green fruits at the beginning of the winter period
  • Synthesized in maturing seeds, establishing dormancy
  • Mobile within the leaf and can be rapidly translocated from the roots to the leaves by the transpiration stream in the xylem
  • Produced in response to environmental stress, such as heat stress, water stress, salt stress
  • Synthesized in all plant parts, e.g., roots, flowers, leaves and stems

Effects[edit]

In Fungi[edit]

Like plants, some fungal species (for example Botrytis cinerea) [18] have an endogenous biosynthesis pathway for ABA. In fungi, it seems to be the MVA biosynthetic pathway that is predominant (rather than the MEP pathway that is responsible for ABA biosynthesis in plants).

In Animals[edit]

ABA has also been found to be present in metazoans, from sponges up to mammals including humans.[19] Currently, its biosynthesis and biological role in animals is poorly known. ABA has recently been shown to elicit potent anti-inflammatory and anti-diabetic effects in mouse models of diabetes/obesity, inflammatory bowel disease, atherosclerosis and influenza infection.[20] In mammalian cells ABA targets a protein known as lanthionine synthetase C-like 2 (LANCL2), triggering an alternative mechanism of activation of peroxisome proliferator-activated receptor gamma (PPAR gamma).[21]

References[edit]

  1. ^ "Abscisic Acid - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 16 September 2004. Identification and Related Records. Retrieved 22 October 2011. 
  2. ^ "ChemSpider database - Abscisic acid - Properties". Retrieved 27 December 2012.  The melting point is decided by experimental data by Tokyo Chemical Industry Ltd.
  3. ^ "ChemSpider database - Abscisic acid - Properties". Retrieved 27 December 2012.  The boiling point is reported there to be predicted by ACD/Labs
  4. ^ Zhu, Jian-Kang (2002). "Salt and Drought Stress Signal Transduction in Plants". Annual Review of Plant Biology 53: 247–73. doi:10.1146/annurev.arplant.53.091401.143329. PMC 3128348. PMID 12221975. 
  5. ^ Seo, M; Koshiba, T (2002). "Complex regulation of ABA biosynthesis in plants". Trends in Plant Science 7 (1): 41–8. doi:10.1016/S1360-1385(01)02187-2. PMID 11804826. 
  6. ^ a b Nambara, Eiji; Marion-Poll, Annie (2005). "Abscisic Acid Biosynthesis and Catabolism". Annual Review of Plant Biology 56: 165–85. doi:10.1146/annurev.arplant.56.032604.144046. PMID 15862093. 
  7. ^ Milborrow, B.V. (2001). "The pathway of biosynthesis of abscisic acid in vascular plants: A review of the present state of knowledge of ABA biosynthesis". Journal of Experimental Botany 52 (359): 1145–64. doi:10.1093/jexbot/52.359.1145. PMID 11432933. 
  8. ^ Siewers, V.; Smedsgaard, J.; Tudzynski, P. (2004). "The P450 Monooxygenase BcABA1 is Essential for Abscisic Acid Biosynthesis in Botrytis cinerea". Applied and Environmental Microbiology 70 (7): 3868–76. doi:10.1128/AEM.70.7.3868-3876.2004. PMC 444755. PMID 15240257. 
  9. ^ Steuer, Barbara; Thomas Stuhlfauth, Heinrich P. Fock (1988). "The efficiency of water use in water stressed plants is increased due to ABA induced stomatal closure". Photosynthesis Research 18 (3): 327–336. doi:10.1007/BF00034837. ISSN 0166-8595. Retrieved 2012-08-10.  [citation needed]
  10. ^ Park, Sang-Youl; P. Fung, N. Nishimura, D. R. Jensen, H. Fuiji, Y. Zhao, S. Lumba et al. (May 2009). "Abscisic acid inhibits type 2C protein phosphatases via the PYR/PYL family of START proteins.". Science Signaling 324. 
  11. ^ Abscisic acid biosynthesis inhibitor, Shigeo Yoshida et al US 7098365 
  12. ^ Finkelstein, Ruth (November 2013). "Abscisic Acid Synthesis and Response". Arabidopsis Book. 11. doi:10.1199/tab.0166. 
  13. ^ DeJong-Hughes, J., et al. (2001) Soil Compaction: causes, effects and control. University of Minnesota extension service
  14. ^ Zhang, Jianhua; Schurr, U.; Davies, W. J. (1987). "Control of Stomatal Behaviour by Abscisic Acid which Apparently Originates in the Roots". Journal of Experimental Botany 38 (7): 1174. doi:10.1093/jxb/38.7.1174. 
  15. ^ Miernyk, J. A. (1979). "Abscisic Acid Inhibition of Kinetin Nucleotide Formation in Germinating Lettuce Seeds". Physiologia Plantarum 45: 63–6. doi:10.1111/j.1399-3054.1979.tb01664.x. 
  16. ^ Chandler, P M; Robertson, M (1994). "Gene Expression Regulated by Abscisic Acid and its Relation to Stress Tolerance". Annual Review of Plant Physiology and Plant Molecular Biology 45: 113–41. doi:10.1146/annurev.pp.45.060194.000553. 
  17. ^ Duan, Lina; D. Dietrich, C. H. Ng, P. M. Y. Chan, R. Bhalerao, M. J. Bennett, J. R. Dinneny. (Jan 2013). "Endodermal ABA Signaling Promotes Lateral Root Quiescence during Salt Stress in Arabidopsis Seedlings". PLANT CELL 2013. tpc.112.107227v1-tpc.112.107227. Retrieved 24 January 2013. 
  18. ^ Sievers, Verena; Kokkelink, Leonie; Smedsgaard, Jørn; Tudzynski, Paul (July 2006). "Identification of an Abscisic Acid Gene Cluster in the Grey Mold Botrytis cinerea". Appl Environ Microbiol. 72. doi:10.1128/AEM.02919-05. 
  19. ^ Na-Hang, Li; Rui-Lin, Hao; Shan-Shan, Wu; Peng-Cheng, Guo; Can-Jiang, Chen; Li-Ping, Pan; He, Ni (2011). "Occurrence, function and potential medicinal applications of the phytohormone abscisic acid in animals and humans". Biochemical Pharmacology 82 (7): 701–712. doi:10.1016/j.bcp.2011.06.042. 
  20. ^ Bassaganya-Riera, J; Skoneczka, J; Kingston, DG; Krishnan, A; Misyak, SA; Guri, AJ; Pereira, A; Carter, AB; Minorsky, P; Tumarkin, R; Hontecillas, R (2010). "Mechanisms of action and medicinal applications of abscisic Acid". Current medicinal chemistry 17 (5): 467–78. doi:10.2174/092986710790226110. PMID 20015036. 
  21. ^ Bassaganya-Riera, J.; Guri, A. J.; Lu, P.; Climent, M.; Carbo, A.; Sobral, B. W.; Horne, W. T.; Lewis, S. N.; Bevan, D. R.; Hontecillas, R. (2010). "Abscisic Acid Regulates Inflammation via Ligand-binding Domain-independent Activation of Peroxisome Proliferator-activated Receptor". Journal of Biological Chemistry 286 (4): 2504–16. doi:10.1074/jbc.M110.160077. PMC 3024745. PMID 21088297.