Jasmonic Acid reaction to plants

The reaction of plants to stress from their environment, be it the plant’s consumers or the environment, involves a series of pathways which induce defenses (Tian, Peiffer, et al.). These pathways involve several hormones which trigger defense responses in plants. Jasmonic acid is a hormone that plants release to control responses from stress, such as damage from weather or herbivores. It has been observed that applying jasmonic acid onto a tomato plant can be used as a pesticide by inducing defenses plants use naturally to deter herbivores from consuming them (Tian, Tooker, et al.; Tian, Peiffer, et al.). Administering jasmonic acid onto a tomato plant can cause plants to grow more trichomes (hair-like structures that grow on the leaf of the plant that make traversing them more difficult for herbivores) (Tian, Tooker, et al.). Tomato plants treated with jasmonic acid have been shown to be less preferable to consume by herbivores as a result of secondary compounds produced, and the herbivores that consume them do not grow as large (Tian, Peiffer, et al.). 

However, artificially inducing plant defenses has been shown to affect the growth of plants, the reproductive process, and may negatively affect the fruit and leaves of the plant (Redman et al.; Koussevitzky et al.)Applying jasmonic acid to tomato plants can result in larger but fewer fruits, the amount of seeds produced, and the success of germination (Redman et al.). Treating plants with jasmonic acid has been shown to enhance the amount of polyphenol oxidase in the chloroplasts of the plants (Koussevitzky et al.) Excess polyphenol oxidase could cause the fruits and/or leaves to brown faster and the fruits to consist of more pigments, which is a sign of an increased rate of cell death (Araji et al.).