Methyl jasmonate (abbreviated MeJA) is a volatile organic compound used in plant defense and many diverse developmental pathways such as

seed germination Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, fern ...

, root growth,

flowering A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechanism ...

fruit ripening Ripening is a process in fruits that causes them to become more palatable. In general, fruit becomes sweeter, less green, and softer as it ripens. Even though the acidity of fruit increases as it ripens, the higher acidity level does not make the ...

, and senescence. Methyl jasmonate is derived from jasmonic acid and the reaction is catalyzed by ''S''-adenosyl--methionine:jasmonic acid carboxyl methyltransferase.

Description

Plants produce jasmonic acid and methyl jasmonate in response to many biotic and abiotic stresses (in particular, herbivory and wounding), which build up in the damaged parts of the plant. The methyl jasmonate can be used to signal the original plant’s defense systems or it can be spread by physical contact or through the air to produce a defensive reaction in unharmed plants. The unharmed plants absorb the airborne MeJA through either the stomata or diffusion through the leaf cell

cytoplasm In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. Th ...

. An herbivorous attack on a plant causes it to produce MeJA both for internal defense and for a signaling compound to other plants.

Defense chemicals

MeJA can induce the plant to produce multiple different types of defense chemicals such as

phytoalexin Phytoalexins are antimicrobial substances, some of which are antioxidative as well. They are defined, not by their having any particular chemical structure or character, but by the fact that they are defensively synthesized ''de novo'' by plants t ...

s (antimicrobial),

nicotine Nicotine is a naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and ''Duboisia hopwoodii'') and is widely used recreationally as a stimulant and anxiolytic. As a pharmaceutical drug, it is used for ...

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

. The protease inhibitors interfere with the insect digestive process and discourage the insect from eating the plant again. MeJA has been used to stimulate traumatic resin duct production in

Norway spruce ''Picea abies'', the Norway spruce or European spruce, is a species of spruce native to Northern, Central and Eastern Europe. It has branchlets that typically hang downwards, and the largest cones of any spruce, 9–17 cm long. It is very clo ...

trees. This can be used as a defense against many insect attackers as a type of vaccine.

Experiments

External application of methyl jasmonate has been shown to induce plant defensive responses against both biotic and abiotic stressors. When treatments of methyl jasmonate were applied to ''Picea abies'' (

), the accumulation of

monoterpene Monoterpenes are a class of terpenes that consist of two isoprene units and have the molecular formula C10H16. Monoterpenes may be linear (acyclic) or contain rings (monocyclic and bicyclic). Modified terpenes, such as those containing oxygen funct ...

and sesquiterpene compounds doubled in the spruce needle tissues, a response that normally is only triggered when the tissue is damaged. In an experiment testing the effect of methyl jasmonate treatments on drought tolerance,

strawberry The garden strawberry (or simply strawberry; ''Fragaria × ananassa'') is a widely grown hybrid species of the genus ''Fragaria'', collectively known as the strawberries, which are cultivated worldwide for their fruit. The fruit is widely ap ...

plants were shown to alter their metabolism and were better able to withstand water stress and drought conditions by lowering the amount of transpiration, and membrane-lipid peroxidation. External application of methyl jasmonate has also shown a propensity for inducing an increased resistance to insect herbivory in some agricultural crops, such as

brassica ''Brassica'' () is a genus of plants in the cabbage and mustard family (Brassicaceae). The members of the genus are informally known as cruciferous vegetables, cabbages, or mustard plants. Crops from this genus are sometimes called ''cole cro ...

s and

tobacco Tobacco is the common name of several plants in the genus ''Nicotiana'' of the family Solanaceae, and the general term for any product prepared from the cured leaves of these plants. More than 70 species of tobacco are known, but the chie ...

. Plants treated with methyl jasmonate and exposed to insect herbivores had significantly lower levels of herbivory, and the insect herbivores had slower development, when compared to untreated plants. In recent experiments, methyl jasmonate has been shown to be effective at preventing bacterial growth in plants when applied in a spray to the leaves. The

antibacterial An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention ...

effect is thought to be because of methyl jasmonate inducing resistance. MeJA is also a plant hormone involved in tendril (root) coiling, flowering, seed and fruit maturation. An increase of the hormone affects flowering time, flower morphology and the number of open flowers. MeJA induces ethylene-forming enzyme activity, which increases the amount of ethylene to the amount necessary for fruit maturation. Increased amounts of methyl jasmonate in plant roots have shown to inhibit their growth. It is predicted that the higher amounts of MeJA activate previously unexpressed genes within the roots to cause the growth inhibition.

Cancer cells

Methyl jasmonate induces

cytochrome C The cytochrome complex, or cyt ''c'', is a small hemeprotein found loosely associated with the inner membrane of the mitochondrion. It belongs to the cytochrome c family of proteins and plays a major role in cell apoptosis. Cytochrome c is high ...

release in the mitochondria of cancer cells, leading to

cell death Cell death is the event of a biological cell ceasing to carry out its functions. This may be the result of the natural process of old cells dying and being replaced by new ones, as in programmed cell death, or may result from factors such as dis ...

, but does not harm normal cells. Specifically, it can cause cell death in

B-cell chronic lymphocytic leukemia Chronic lymphocytic leukemia (CLL) is a type of cancer in which the bone marrow makes too many lymphocytes (a type of white blood cell). Early on, there are typically no symptoms. Later, non-painful lymph node swelling, feeling tired, fever, nigh ...

cells taken from human patients with this disease and then treated in tissue culture with methyl jasmonate. Treatment of isolated normal human blood lymphocytes did not result in cell death.

References

External links