Usage and action mechanism of oxylipins including jasmonic acid on physiological aspects of fruit production

Plant hormones are associated with many physiological aspects in fruit tree growth and fruit production. Since jasmonates (jasmonic acid (JA) and methyl ester of JA (MeJA)), which are oxylipins from linolenic acid, were found in plants including fruits, many physiological and molecular actions of jasmonates to regulate fruit development and stress tolerance from the environment in fruit production have been studied. Jasmonoyl-L-isoleucine (JA-Ile) is a transporting and signaling substance for JA action in plants. In the JA signaling pathway, MYC transcription factors are key regulators, and the jasmonate-ZIM domain (JAZ) negatively affects MYC transcription factors in JA signaling. Jasmonates can promote anthocyanin production in fruit through the effects of MYB transcription factors. A chemically stable and practical compound in the field, the JA analog n-propyl dihydrojasmonate, has been developed to improve fruit coloration. Jasmonates interact with some other plant hormones. For example, the effects of jasmonates on ethylene metabolism and signaling differ with fruit growth stage. Jasmonate treatment before fruit maturation enhances ethylene production with ethylene biosynthesis and signaling genes. In contrast, jasmonate treatment after fruit maturation decreases ethylene biosynthesis. Jasmonates can mitigate abiotic and biotic stresses from the environment, such as drought, salt, temperature, and disease. When fruit or a fruit tree encounters environmental stress, the stress quickly increases levels of jasmonates, which acts as a kind of elicitor. In fact, treatment of fruit with jasmonates decreased the severity of chilling injury during storage and inhibited fungal infection. This review discusses the usage and action mechanisms of oxylipins including jasmonates on fruit coloration, crosstalk with other plant hormones, and environmental stresses in fruit production.