Oxygenated lipid signals regulate the outcomes of maize interactions with mycotoxigenic fungi and insect herbivores
Dr. Eli Borrego
Thomas H. Gosnell School of Life Sciences, RIT
Oxylipins are oxygenated fatty acids that regulate nearly every known biological process in mammalian systems, where they are known as eicosanoids, prostaglandins, and leukotrienes. Virtually nothing is known about the role of plant oxylipins with the exception of the phytohormone jasmonic acid. A unique collection maize knockout lines disrupted in lipoxygenase and oxophytodienoic acid reductase 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 lipoxygenases (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 16 defense 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.
Eli Borrego was born and raised in the Rio Grande Valley in south Texas. His undergraduate studies were at Texas A&M University-Kingsville and he received a PhD in Plant Pathology from Texas A&M University in 2014. After his graduate studies, he worked as Postdoctoral Research Scholar and Assistant Research Scientist in TAMU’s Department of Plant Pathology and Microbiology. There, he worked with Professor Michael Kolomiets exploring a group of poorly understood fatty acid derived hormones, known as oxylipins, in plant-pathogen and -insect interactions using maize as a model system. His expertise with mass spectrometry and deep understanding of oxylipin biology helped the group secure $2M in research funding from 2015 to 2018. At TAMU, Eli has helped train over 60 undergraduate, graduate, and international scholars in molecular plant pathology and entomology. He is now an Assistant Professor at RIT in the Thomas H Gosnell School of Life Sciences.
When and Where
1:00 PM-2:00 PM
Thomas Gosnell Hall
Open to the Public