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ARS Home » Southeast Area » Gainesville, Florida » Center for Medical, Agricultural and Veterinary Entomology » Chemistry Research » Research » Research Project #434496

Research Project: Molecular and Biochemical Characterization of Biotic and Abiotic Stress on Plant Defense Responses in Maize

Location: Chemistry Research

Project Number: 6036-11210-001-00-D
Project Type: In-House Appropriated

Start Date: Mar 26, 2018
End Date: Mar 25, 2023

Objective:
The overall goal of this project is to provide stakeholders with increased knowledge of the innate immune responses of maize to insect and fungal attack and determine how these defense mechanisms are affected by abiotic stress factors. Objective 1. Molecularly characterize the production and function of chemical defense responses to biotic and abiotic stress of maize to evaluate and elucidate the cumulative effect of multiple stressors. Sub-objective 1A. Molecularly characterize defense metabolites (i.e., fatty acids) and their mediated plant responses in fungal infected tissues, and determine the impact of abiotic stress on these responses. Sub-objective 1B. Identify maize genes involved in the production of chemical defenses against insect pests, use mutants in these genes to elucidate the production and function of chemical defenses in insect resistance, and assess the effect of abiotic stress on these defenses. Objective 2. Identify and functionally characterize genetic components that mediate the defense response of maize to biotic stress, and determine the impact of abiotic stress on these mechanisms to mitigate yield loss.

Approach:
The production of select chemical defenses in maize in response to specific biotic stressors will be analyzed by profiling novel free fatty acids, hormones, inducible volatiles, and flavones in maize in response to fungal or insect attack. Candidate genes responsible for the biosynthesis and regulation of these metabolites will be identified using co-expression analysis and forward genetic approaches. Once the genes have been selected they will be prioritized for further characterization and mutant resources such as the UniformMu maize population mined for mutations in those genes and the presence of mutant alleles confirmed by gene-by –gene PCR genotyping. Mutants will also be generated in genes of interest using CRISPR/Cas9 technology. Loss-of-function mutants, coupled with metabolic profiling and bioassays will then be used to assess the function of select high priority candidate genes and their products in biotic stress resistance. Furthermore, defense responses will be characterized under abiotic stress conditions (heat, drought, elevated carbon dioxide) to determine the integrity of defense pathways under situations of combinatorial stress.