Temasek Senior Investigator Temasek Life Sciences Laboratory Singapore, Singapore
Fungal oxylipins serve as crucial signaling molecules for growth, development, and host colonization. This study examines the role of two important oxylipin-producing enzymes, Linoleate Diol Synthase and heme peroxidase, in regulating fungal morphogenesis using the rice blast pathosystem. Loss of either enzyme resulted in significantly longer germ tubes leading to delayed transition from vegetative-to-pathogenic growth. We attributed this phenomenon to the absence of octadecanoid oxylipins 7,8-DiHODE and 10R-HPODE. Interestingly, Magnaporthe contains a unique secreted lipoxygenase with a functional manganese binding site, predicted to be required for synthesis of the oxylipin jasmonic acid. MnLOX was essential for viability and MnLox-GFP partially colocalized with the endoplasmic reticulum, followed by secretion via the apoplast and assemblage at the pit fields or plasmodesmata during early host invasion. Deletion of the signal peptide rendered the protein cytoplasmic without affecting its functionality. Metabolomics analyses on the aforementioned mutants and variants will be shared together with phenotypic similarities between oxylipin and cAMP signaling cascades. Mutants in the cAMP signaling failed to induce appressorium formation, a defect that was overcome by the addition of jasmonate and intermediary oxylipins. This ongoing research aims to elucidate the role of oxylipins and their interactions with other signaling pathways in regulating pathogenicity in Rice Blast.
