Figure 9.

Distribution of Plastid-Localized JA Biosynthesis Enzymes in 5-d Light-Stressed Leaf or Isolated PG from the Wild Type and k1 k3.

NadjSPC are normalized within each protein, illustrating the protein’s relative depletion/enrichment in each total leaf or PG preparation. An additional AOC (AOC3) is putatively involved in JA biosynthesis but was not identified in leaf or PG preparations. The plastid-localized steps of the JA biosynthesis pathway begin with peroxidation of linolenic acid by 13-lipoxygenase (13-LOX), which may act on the free or esterified form of the fatty acid. The peroxidized fatty acid is subsequently epoxidized by AOS and cyclized by AOC to form OPDA, which is exported to the peroxisome for subsequent processing by OPDA reductase and three rounds of β-oxidation to produce the JA phytohormone. The relative NadjSPC of LOX2 is set to 0.0129; of LOX3, 0.0147; of LOX4, 0.0040; of AOS, 0.0657; of AOC1, 0.0012; of AOC2, 0.0012, of AOC4, 0.0001; and of OPR, 0.0001. wt, the wild type.