Jasmonate



The jasmonates (JAs) are a group of plant hormones which help regulate plant growth and development. Jasmonates include jasmonic acid and its esters, such as methyl jasmonate (MeJa). Like the related prostaglandin hormones found in mammals, the jasmonates are cyclopentanone derivatives which are derived biosynthetically from fatty acids. They are biosynthesized from linolenic acid by the octadecanoid pathway.

The level of JA in plants varies as a function of tissue and cell type, developmental stage, and in response to several different environmental stimuli. High levels of JA are also found in flowers and pericarp tissues of developing reproductive structures and in the chloroplasts of illuminated plants; JA levels also increase rapidly in response to mechanical perturbations such as tendril coiling and when plants suffer wounding.

Demonstrated roles of JA in planta include:
 * JA and MeJA inhibit the germination of nondormant seeds and stimulate the germination of dormant seeds
 * High levels of JA encourage the accumulation on storage proteins; genes encoding vegetative storage proteins are JA responsive and tuberonic acid (a JA derivative) has been proposed to play a role in the formation of tubers
 * JA application can induce chlorosis and inhibition of genes encoding proteins involved in photosynthesis, although the purpose of this response is unknown it is proposed that this response to JA could help reduce the plant's capacity for carbon assimilation under conditions of excess light or carbon
 * The role of JA accumulation in flowers and fruit is unknown, however it may be related to fruit ripening (via ethylene), fruit carotenoid composition, and expression of genes encoding seed and vegetative storage proteins
 * JA plays a role in insect and disease resistance, many genes during plant defense are induced by JA; JA and ethylene may act together in defense response