Jasmonate Signaling and Stress Management in Plants

Jasmonates (JAs), a group of plant oxylipins are produced by the oxidation of polyunsaturated fatty acids (PUFA), following one of the seven divergent branches of the lipoxygenase (LOX) pathway. The prime branch of JA biosynthesis is allene oxide synthase (AOS), which utilizes 13-hydroperoxide from α-linolenic acid (18:3, α-LeA). PUFA, used in the biosynthesis of JA and released from chloroplast membrane, is converted into 9- or 13-hydroperoxides through the LOX pathway, which further enters the AOS pathway for the production of free JA. Many derivatives of JAs are explored and isolated from plants such as free JA, methyl jasmonate (Me-JA), cis-jasmone, jasmonyl isoleucine (JA-Ile), and jasmonoyl ACC (JA-ACC). In recent years, breakthroughs have been made in the field of JA's potential as a new class of plant growth regulator due to its regulatory role in seed germination, primary root growth, lateral and adventitious root development, tuber formation, pollen tube development, spikelet formation, and development in rice and other crops. The defensive role of JA and its methyl ester–Me-JA has been well explored under various biotic and abiotic stresses. Physiological and anti-stressor roles played by JAs are performed through the signal transduction pathway, which involves various protein complexes. Advances have been made in the identification of JASMONATE ZIM DOMAIN (JAZ) proteins, which interact with various transcription factors and co-repressor proteins to confirm JA's related responses at the biochemical and molecular level. In this chapter, the questions being addressed are about the advances in JA biosynthesis, nature of receptors, and the network involved in JA signaling for stress responses.