Chemistry and Materials Science Seminar: Lipid signals govern maize-fungal and -insect interactions

Chemistry and Materials Science Seminar
Lipid signals govern maize-fungal and -insect interactions

Dr. Eli Borrego
Assistant Professor
Thomas H. Gosnell School of Life Sciences

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This seminar may be attended in person in 1174 Gosnell Hall or online via Zoom.

Abstract:
Oxylipins are oxygenated fatty acids that govern nearly all known biological process in mammals. There they are known as eicosanoids, prostaglandins, and leukotrienes and are relatively well-studied, however, virtually nothing is known about the role of plant oxylipins. A unique collection maize knockout lines disrupted in lipoxygenase (LOX) and oxophytodienoic acid reductase (OPR) genes was utilized to explore the role of oxylipins in maize interactions with fungi and insects. The biochemical similarity of oxylipins across all kingdoms prompts the intriguing hypothesis that during plant-fungal interactions oxylipins are reciprocally exchanged to mediated chemical communication between the organisms. This “lipid language” relies on LOX in plants and Psi producing oxygenases (Ppo) in fungi, however the specific genes, enzymes, and products remain undefined in any plant-fungal system. To test this hypothesis, we employed the agro-economically relevant plant-fungal interaction between maize seed and Aspergillus flavus. A set of oxylipin mutants of both organisms were used to characterize the role of host- and pathogen-derived oxylipins in fungal colonization, conidiation, and aflatoxin production. We found that individual oxylipin biosynthetic enzymes in both host and pathogen determine the disease outcome and regulate specific pathogenicity processes. LOX10 is the sole maize isoform responsible for production of green leaf volatiles (GLVs) which directly and indirectly provide defense against insects. Alongside a defective herbivory defense response in local tissue, knockout mutants of lox10 are also unable to accumulate defenses related oxylipins, termed systemic oxylipins signals (SOS), in systemic tissue determined by liquid chromatography- mass spectrometry. In response to herbivory, lox10 mutants were unable to accumulate normal concentrations of oxylipins in phloem-enriched sap compared to WT. Remarkably, RNAseq analysis revealed that roots but not leaves of lox10 mutants are perturbed in normal expression of oxylipin biosynthesis compared with WT. In accordance, concentrations of specific oxylipins in xylem-enriched sap from roots are induced by herbivory. In addition to the proposed LOX10-dependent SOS, another potential mode of action for LOX10 during long-distance systemic signaling is through direct LOX10 protein movement via the vasculature These results support the role of diverse oxylipin involvement in maize communication with A. flavus and during systemic defense against insects.

Speaker Bio:
Eli was born and raised in the Rio Grande Valley of South Texas. He graduated with a Ph.D. in Plant Pathology in 2014 and joined the Thomas H. Gosnell School of Life Sciences in 2019. His program explores lipid signals in plant interactions with microbes, insects, and other stresses. The research addresses problems such as insect and pathogen resistance, drought tolerance, and heavy metal accumulation in crop species.

Intended Audience:
Undergraduates, graduates, experts. Those with interest in the topic.

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