Dioxygenase JID1 mediates the modification of OPDA to regulate jasmonate homeostasis

The phytohormone jasmonate (JA), including jasmonic acid and its oxylipin derivatives, is essential for plant resistance against various stresses 1,2 .The biosynthetic pathway of JA is initiated from α-linolenic acid (18:3) that is converted to 12-oxo-phytodienoic acid (OPDA) by 13-Lipoxygenase (LOX), Allene Oxide Synthase (AOS), and Allene Oxide Cyclase (AOC), which is then reduced to OPC-8:0 by OPDA Reductase3 (OPR3) and activated by OPC-8:0 CoA Ligase1 (OPCL1) followed by three cycles of β-oxidation catalyzed by acyl-CoA Oxidase (ACX), Multifunctional Protein (MFP), and 3-ketoacyl-CoA Thiolase (KAT) to yield jasmonic acid.Jasmonic acid is further catalyzed by Jasmonate Resistant1 (JAR1) to generate jasmonoyl-l-isoleucine (JA-Ile) 1 .Excess jasmonic acid and JA-Ile are hydroxylated by Jasmonate-Induced Oxygenases (JOX1, JOX2, JOX3, and JOX4) that belong to 2-oxoglutarate/Fe(II)-dependent dioxygenase (2OGD) superfamily, and cytochrome P450 enzymes (CYP94B3, CYP94B1, and CYP94C1) for the regulation of JA homeostasis, respectively 3,4 , thereby driving the growthdefense tradeoff in plants.OPDA is not only the first cyclic precursor of JA biosynthesis but also an independent signaling molecule 5,6 .OPDA coordinates with or without the canonical JA pathway to regulate a unique subset of genes and thereby orchestrates plant defense against pathogen infection and insect attack 5,7 .In response to stress, accumulated OPDA binds cyclophilin 20-3 to form a complex with Serine Acetyltransferase 1, which facilitates the formation of a hetero-oligomeric cysteine synthase complex with