LOX1 and PLP1 dependent transcriptional reprogramming is essential for injury induced conidiophore development in a filamentous fungus
We need to learn more about the components of the fungal damage response that are similar and well-studied in plants and animals, such as the role of oxidized lipids in mechanical stress. Using a genetic approach, mass spectrometry, and phenotypic analysis, we describe the functional role of a patatin-like phospholipase (plp1) and a unique lipoxygenase (lox1) with biosynthetic function in the production of oxidized PUFA derivatives by mechanical injury in the model fungus Trichoderma atroviride. lox1 and plp1 are co-expressed and regulated by damage signaling and sensing components. Phenotypic analysis revealed an essential defect in the emergence of aerial hyphae in the lox1 and plp1 null mutant strains, blocking injury-induced conidiation. In addition, functional loss analysis demonstrated that both genes are essential for producing the wound oxylipin 13-HODE (13-hydroxy octadecadienoic acid) and the transcriptional reprogramming required for conidiation. T. atroviride requires LOX1 and PLP1 to induce at early stages of the response transcription factors involved in asexual development like a BrlA homolog, Hox2, and Azf1, and at a later stage to activate lipid metabolism and structural proteins involved in aerial mycelium emergence. Our study emphasizes how the co-function of lox1 and plp1, during the response to wounding, regulate the molecular and physiological processes that lead to reproductive aerial mycelium development to warrant survival through conidiation. Overall design: To decipher the biological function of LOX1 and PLP1 in response to wounding, we generated mutant strains of LOX1 and PLP1. We sequenced mRNA obtained from mycelium of WT and mutants strains (dlox1 and dplp1) at three times of response: control (0 h), 90 min and 4 h after mechanical injury. Differential gene expression was performed contrasting control versus injury using data obtained from RNA-seq analysis.