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POSTERS: Biochemistry and cell biology

Role of lipid droplets in self-resistance of Cercospora cf. flagellaris to cercosporin
Maria Izabel Costa de Novaes - Louisiana State University. Sara Thomas-Sharma- Louisiana State University, Clark Robertson- Louisiana State University

Cercospora cf. flagellaris, the causal agent of Cercospora leaf blight (CLB), is a yield-limiting pathogen of soybean in Louisiana and many other Gulf states. C. cf. flagellaris produces a perylenequinone toxin, cercosporin, largely responsible for the leaf-blighting symptoms of CLB. This toxin absorbs visible light, generating reactive oxygen species (ROS) that damages cell membranes and releases nutrients to the fungus. In a perylenequinone producing endolichenic fungus, lipid droplets (organelles containing neutral lipids) trap the toxin preventing ROS production. Lipid droplet-deficient yeast mutants show an increase in susceptibility to certain fungicides. We investigate if C. cf. flagellaris traps cercosporin in lipid droplets for self-resistance to the toxin. In two independent runs, three isolates of C. cf. flagellaris were grown in liquid culture and after five days the amount of cercosporin and total lipids were measured. Results showed, on average, isolates that produced high (23.5 and 37 ?g/ml) and low (12 ?g/ml) cercosporin, had high (24.75 and 33.83 g/L) and low (10.8 g/L) amounts of total lipids, respectively. The experiment will be expanded to include other Cercospora spp., known to differ in cercosporin production. Confocal microscopy will be used to determine co-localization of cercosporin in lipid droplets. If lipid droplets trap cercosporin, this could provide new possibilities to control CLB. Fungicides that inhibit lipid synthesis will be tested against C. cf. flagellaris with the final goal of translating our findings into practical CLB management.