Phd in ENVIRONMENTAL AND EVOLUTIONARY BIOLOGY

Thesis title: The Role of CRZ1 in Synchronizing Lipid Metabolism, Oxylipin Synthesis and Fumonisins Production

Fight hard or die trying, this could be the extreme synthesis of a pathogenic attack on susceptible plants. In this inter-kingdom communication, the interaction between the two organisms represents a key element for understanding how the pathogen develops inside the host, and on which molecules its virulence is based. Lipid molecules such as oxylipins, sphingolipids, and free fatty acids are among the signals through which the two organisms can communicate. The fine-tuning of these signals by either side guarantees success or defeat, and even “hacking” them can be a way to win. In this scenario, the transcription factor Crz1 integrates itself as a key regulator of various pathways, from the production of specific lipid molecules to the stress response. In this study, its function as a stress response factor and its involvement in lipid metabolism during interaction with Zea mays was demonstrated. In fact, in the FvCrz1∆ deleted strain, lower growth was found during the infection and an imbalance in the production of fatty acids and oxylipins. To confirm its (upstream) role as a virulence regulator, the deleted mutant showed reduced production of mycotoxins. From a transcriptomic regulatory perspective, crz1 regulates numerous pathways during infection, including the production of fatty acids and sphingolipids. In particular, the role of phospholipase A2 (FvPla2) seems to emerge as a direct link between Crz1 and lipid production, through which fusarium, via crz1, regulates the availability of FFA during infection and the consequent production of oxylipins, which enhance the production of mycotoxins downstream. Elucidating its role in the interaction of Fusarium verticillioides and Zea mays will allow a critical understanding of gene regulation in both pathogens and hosts and the development of fine-tuned defense strategies.