Levels of oxygenated Fatty acids in young corn and sunflower plants.

Three oxygenated unsaturated fatty acids were investigated to determine whether they were present in seedlings of corn (Zea mays L. cv. NK PX443) and sunflower (Helianthus annuus L. cv. Sundak). The three compounds, 13-hydroxy-12-oxo-cis-9-octadecenoic acid (I), 13-hydroxy-12-oxo-cis,cis-9, 15-octadecadienoic acid (II), and 12-oxo-cis,cis-10, 15-phy-todienoic acid (III), were detected and estimated by gas chromatography-mass spectrometry selected ion monitoring of their trimethylsilyloxy, methyloxime derivatives with 20-carbon analogs added as internal standards. In corn, the concentration of III increased between 5 and 10 days, while I and II remained relatively constant. A higher concentration of II was observed in corn seedlings grown in the light than those grown in the dark. Wounding increased the levels of all three compounds. In sunflower seedlings, the concentrations of I, II, and III increased between 6 and 10 days. The intracellular concentration of III in 10-day-old light-grown seedlings was estimated to be 200 nm in corn and 40 nm in sunflower.