Abscisic acid
 |
|
| Names | |
|---|---|
|
Systematic IUPAC name
(2Z,4E)-5-[(1S)-1-hydroxy-2,6,6-trimethyl-4-oxocyclohex-2-en-1-yl]-3-methylpenta-2,4-dienoic acid
|
|
| Other names
(2Z,4E)-(S)-5-(1-Hydroxy-2,6,6-trimethyl-4-oxo-2-cyclohexen-1-yl)-3-methyl-2,4-pentanedienoic acid
|
|
| Identifiers | |
21293-29-8 
|
|
| 3D model (Jmol) | Interactive image |
| 3DMet | B00898 |
| Abbreviations | ABA |
| 2698956 | |
| ChEBI |
CHEBI:2635 
|
| ChEMBL |
ChEMBL288040
|
| ChemSpider |
4444418
|
| ECHA InfoCard | 100.040.275 |
| EC Number | 244-319-5 |
| MeSH | Abscisic+Acid |
| PubChem | 5280896 |
| RTECS number | RZ2475100 |
|
|
|
|
| Properties | |
| C15H20O4 | |
| Molar mass | 264.32 g·mol−1 |
| Appearance | Colorless crystals |
| Density | 1.193 g/mL |
| Melting point | 163 °C (325 °F; 436 K) |
| Boiling point | 458.7 °C (857.7 °F; 731.8 K) sublimes |
| log P | 1.896 |
| Acidity (pKa) | 4.868 |
| Basicity (pKb) | 9.129 |
| Hazards | |
| S-phrases | S22, S24/25 |
|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|
|
 (what is ?) |
|
| Infobox references | |
Abscisic acid (ABA), also known as Dormin, Dormic acid (DMA), is best known as 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.
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. The plant genes for ABA biosynthesis and sequence of the pathway have been elucidated. ABA is also produced by some plant pathogenic fungi via a biosynthetic route different from ABA biosynthesis in plants.
Abscisic acid owes its names to its role in the abscission of plant leaves. In preparation for winter, ABA is produced in terminal buds. 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.
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.
Seed germination is inhibited by ABA in antagonism with gibberellin. ABA also prevents loss of seed dormancy.
Several ABA-mutant Arabidopsis thaliana plants have been identified and are available from the - 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.
...
Wikipedia