12-OPDA Reductase and OPC-8:0 CoA Ligase Mediate Jasmonic Acid Synthesis in <i>Lasiodiplodia iranensis</i>

Jasmonic acid (JA), a phytohormone with a distinct flavor, is an important fragrance ingredient. The filamentous fungi <i>Lasiodiplodia</i> sp. can produce JA via fermentation. Based on comparative transcriptome analysis of <i>L. iranensis</i> M2017288 in static and shaking culture, 13 differentially expressed genes potentially related to JA synthesis were screened, including <i>g4442</i> and <i>g8524</i>, annotated as 12-OPDA reductase (<i>Li</i>OPR) and OPC-8:0 CoA ligase (<i>Li</i>OPCL), respectively. Quantitative real-time PCR and RNA interference assays confirmed that <i>g4442</i> and <i>g8524</i> expression levels were positively correlated with the JA synthesis. Recombinant <i>Li</i>OPR protein utilized (15<i>Z</i>)-12-oxophyto-10,15-dienoic acid (12-OPDA) to generate (9<i>S</i>,13<i>S</i>,15<i>Z</i>)-12-oxo-10,11-dihydrophyto-15-enoate (OPC8:0). JA was detected in cascade reactions of both recombinant <i>Li</i>OPR and <i>Li</i>OPCL coupled with <i>Saccharomyces cerevisiae</i>. Phylogenetic analyses revealed that <i>Li</i>OPR and <i>Li</i>OPCL belong to a different evolutionary branch from plants, suggesting that they are essential enzymes for fungal JA synthesis, which is worthy of further investigation.