874393-55-2Relevant academic research and scientific papers
Linolenate 9R-dioxygenase and allene oxide synthase activities of lasiodiplodia theobromae
Jerneren, Fredrik,Eng, Felipe,Hamberg, Mats,Oliw, Ernst H.
experimental part, p. 65 - 73 (2012/06/15)
Jasmonic acid (JA) is synthesized from linolenic acid (18:3n-3) by sequential action of 13-lipoxygenase, allene oxide synthase (AOS), and allene oxide cyclase. The fungus Lasiodiplodia theobromae can produce large amounts of JA and was recently reported to form the JA precursor 12-oxophytodienoic acid. The objective of our study was to characterize the fatty acid dioxygenase activities of this fungus. Two strains of L. theobromae with low JA secretion (～0.2 mg/L medium) oxygenated 18:3n- 3 to 5,8-dihydroxy-9Z,12Z,15Z- octadecatrienoic acid as well as 9R-hydroperoxy-10E,12Z,15Z-octadecatrienoic acid, which was metabolized by an AOS activity into 9-hydroxy-10-oxo-12Z,15Z- octadecadienoic acid. Analogous conversions were observed with linoleic acid (18:2n-6). Studies using [11S-2H]18:2n-6 revealed that the putative 9R-dioxygenase catalyzed stereospecific removal of the 11R hydrogen followed by suprafacial attack of dioxygen at C-9. Mycelia from these strains of L. theobromae contained 18:2n-6 as the major polyunsaturated acid but lacked 18:3n-3. A third strain with a high secretion of JA (～200 mg/L) contained 18:3n-3 as a major fatty acid and produced 5,8-dihydroxy-9Z,12Z,15Z- octadecatrienoic acid from added 18:3n-3. This strain also lacked the JA biosynthetic enzymes present in higher plants.
