Jasmonic acid (JA) is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

found in several plants including

jasmine Jasmine (botanical name: ''Jasminum'', pronounced ) is a genus of shrubs and vines in the olive family of Oleaceae. It contains around 200 species native to tropical and warm temperate regions of Eurasia, Africa, and Oceania. Jasmines are wid ...

. The molecule is a member of the

jasmonate Jasmonate (JA) and its derivatives are lipid-based plant hormones that regulate a wide range of processes in plants, ranging from growth and photosynthesis to reproductive development. In particular, JAs are critical for plant defense against herb ...

class of

plant hormone Plant hormones (or phytohormones) are signal molecules, produced within plants, that occur in extremely low concentrations. Plant hormones control all aspects of plant growth and development, including embryogenesis, the regulation of Organ (anat ...

s. It is biosynthesized from linolenic acid by the octadecanoid pathway. It was first isolated in 1957 as the methyl

ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...

of jasmonic acid by the Swiss chemist Édouard Demole and his colleagues.

Biosynthesis

Its

biosynthesis Biosynthesis, i.e., chemical synthesis occurring in biological contexts, is a term most often referring to multi-step, enzyme-Catalysis, catalyzed processes where chemical substances absorbed as nutrients (or previously converted through biosynthe ...

starts from the fatty acid

linolenic acid Linolenic acid is a type of naturally-occurring fatty acid. It can refer to either of two octadecatrienoic acids (i.e. with an 18-carbon chain and three double bonds, which are found in the '' cis'' configuration), or a mixture of the two. Lino ...

, which is oxygenated by

lipoxygenase Lipoxygenases () (LOX) are a family of (non- heme) iron-containing enzymes, more specifically oxidative enzymes, most of which catalyze the dioxygenation of polyunsaturated fatty acids in lipids containing a cis,cis-1,4- pentadiene into ce ...

(13-LOX), forming a

hydroperoxide Hydroperoxides or peroxols are Chemical compound, compounds of the form ROOH, where R stands for any group, typically Organic compound, organic, which contain the hydroperoxy functional group (). Hydroperoxide also refers to the hydroperoxide anio ...

. This peroxide then cyclizes in the presence of allene oxide synthase to form an allene oxide. The rearrangement of allene oxide to form 12-oxophytodienoic acid is catalyzed by the enzyme allene oxide cyclase. A series of β-oxidations results in 7-isojasmonic acid. In the absence of enzyme, this isojasmonic acid isomerizes to jasmonic acid. JasmonicAcidBiosyn

Function

The major function of JA and its various metabolites is regulating plant responses to abiotic and biotic stresses as well as plant growth and development. Regulated plant growth and development processes include growth inhibition,

senescence Senescence () or biological aging is the gradual deterioration of Function (biology), functional characteristics in living organisms. Whole organism senescence involves an increase in mortality rate, death rates or a decrease in fecundity with ...

tendril In botany, a tendril is a specialized Plant stem, stem, leaf or Petiole (botany), petiole with a thread-like shape used by climbing plants for support and attachment, as well as cellular invasion by parasitic plants such as ''Cuscuta''. There ar ...

coiling, flower development and leaf abscission. JA is also responsible for

tuber Tubers are a type of enlarged structure that plants use as storage organs for nutrients, derived from stems or roots. Tubers help plants perennate (survive winter or dry months), provide energy and nutrients, and are a means of asexual reproduc ...

formation in potatoes and yams. It has an important role in response to wounding of plants and

systemic acquired resistance Systemic acquired resistance (SAR) is a "whole-plant" resistance response that occurs following an earlier localized exposure to a pathogen. SAR is analogous to the innate immune system found in animals, and although there are many shared aspects b ...

. The Dgl gene is responsible for maintaining levels of JA during usual conditions in ''

Zea mays Maize (; ''Zea mays''), also known as corn in North American English, is a tall stout Poaceae, grass that produces cereal grain. It was domesticated by indigenous peoples of Mexico, indigenous peoples in southern Mexico about 9,000 years ago ...

'' as well as the preliminary release of jasmonic acid shortly after being fed upon. When plants are attacked by insects, they respond by releasing JA, which activates the expression of

protease inhibitors Protease inhibitors (PIs) are medications that act by interfering with protease, enzymes that cleave proteins. Some of the most well known are antiviral drugs widely used to treat HIV/AIDS, hepatitis C and COVID-19. These protease inhibitors pre ...

, among many other anti-herbivore defense compounds. These protease inhibitors prevent proteolytic activity of the insects' digestive proteases or "salivary proteins", thereby stopping them from acquiring the needed nitrogen in the

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

for their own growth. JA also activates the expression of Polyphenol oxidase which promotes the production of

quinoline Quinoline is a heterocyclic aromatic organic compound with the chemical formula C9H7N. It is a colorless hygroscopic liquid with a strong odor. Aged samples, especially if exposed to light, become yellow and later brown. Quinoline is only sl ...

s. These can interfere with the insect's enzyme production and decrease the nutrition content of the ingested plant. JA may have a role in pest control. Indeed, JA has been considered as a seed treatment in order to stimulate the natural anti-pest defenses of the plants that germinate from the treated seeds. In this application jasmonates are sprayed onto plants that have already started growing. These applications stimulate the production of protease inhibitor in the plant. This production of protease inhibitor can protect the plant from insects, decreasing infestation rates and physical damage sustained due to herbivores. However, due to its antagonistic relationship with

salicylic acid Salicylic acid is an organic compound with the formula HOC6H4COOH. A colorless (or white), bitter-tasting solid, it is a precursor to and a active metabolite, metabolite of acetylsalicylic acid (aspirin). It is a plant hormone, and has been lis ...

(an important signal in pathogen defense) in some plant species, it may result in an increased susceptibility to viral agents and other pathogens. In ''

'',

and JA are mediated by NPR1 (nonexpressor of pathogenesis-related genes1), which is essential in preventing herbivores from exploiting this antagonistic system. Armyworms (''

Spodoptera ''Spodoptera'' is a genus of moths of the family Noctuidae Species description, erected by Achille Guenée in 1852. Many are known as Pest (organism), pest insects. The larvae are sometimes called armyworms. The roughly thirty species are distrib ...

'' caterpillars), through unknown mechanisms, are able to increase the activity of the

pathway in maize, resulting in the depression of JA synthesis, but thanks to NPR1 mediation, JA levels aren't decreased by a significant amount.

Derivatives

Jasmonic acid is also converted to a variety of derivatives including the

methyl jasmonate. This conversion is catalyzed by the jasmonic acid carboxyl methyltransferase enzyme. It can also be conjugated to amino acids in some biological contexts. Decarboxylation affords the related fragrance jasmone.

References

* {{DEFAULTSORT:Jasmonic Acid Plant hormones Acetic acids Cyclic ketones Enones Cyclopentanes