Fatty Acid Signaling Pathway and Its Role in Plant Defense

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Plant diseases have a devastating impact on agricultural production and food supply every year. The outcome of the interaction of plants with a given pathogen is governed by several factors, including the genotype, the physiological state of the plant, environmental signals and, any specific interactions that might occur between the activated signaling pathways. Among various signaling molecules proposed to modulate defense responses, salicylic acid (SA) and jasmonic acid (JA) elicit distinct responses and undergo extensive cross talk, which is likely to influence the amplitude and magnitude of various signals leading to a resistance response. Previous work from the PI's laboratory has shown that SSI2 encoded stearoyl-ACP desaturase regulates the levels of unsaturated fatty acids (FA) in the cell and the levels of oleic acid are critical in regulating defense pathways. Three genes have been identified, which participate in the prokaryotic pathway of FA biosynthesis, and a loss-of-function of which restores the various phenotypes in ssi2 mutant plants. Functional analysis of these genes indicates that oleic acid (18:1) levels regulated by glycerolipid metabolism play an important role in the regulation of defense signaling pathways. This project aims to characterize the FA signaling pathway further by carrying out biochemical and molecular analysis of previously identified suppressor mutants, by isolation and characterization of additional mutations that are able to revert the ssi2 mutant to wild type-like and identify the signal molecule(s) responsible for defense-related signaling. Characterization of the FA signaling pathway and deciphering its role in defense would provide critical information about how various pathways interact with each other. This would have enormous implications, as it would permit the manipulation of multiple defense signaling pathways at the same time and engineer crops that are resistant to a wide variety of bacterial, fungal and viral pathogens. The research will facilitate training of undergraduate, graduate and postdoctoral students and enhance the infrastructure of research through sharing of ideas and materials generated by the project. The aim is to foster a community of undergraduate students and provide minority students with progressively sophisticated scientific experiences. The PIs also plan to integrate research with extension services available at UK to enhance awareness of the recent advances in crop resistance and improve attitude towards genetically modified crops among farmers and agribusiness representatives.