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ARS Home » Southeast Area » New Orleans, Louisiana » Southern Regional Research Center » Food and Feed Safety Research » Research » Research Project #438243

Research Project: Genes and Genetic Networks Underlying Resistance to Aspergillus flavus In Corn

Location: Food and Feed Safety Research

Project Number: 6054-42000-025-15-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Sep 1, 2020
End Date: Aug 31, 2023

Objective:
(1) Comparative transcriptome analysis between resistant vis-à-vis susceptible near-isogenic lines to identify genes/miRNAs induced in response to Aspergillus (A.) flavus infection in corn; (2) Construction of resistance associated coexpression networks to identify A. flavus resistance gene/miRNA modules; and (3) Functional validation of the candidate resistance genes via evaluation of transgenic overexpressers or knock-out mutants for A. flavus resistance. Transgenic corn developed with the candidate genes will be tested against A. flavus and other microbial pathogens. Candidate resistance genes identified in this study and co-localized in known major resistance quantitative trait loci (QTLs) will lead to the development of functional markers for future use in marker-assisted breeding.

Approach:
Genome-wide transcriptome analysis using highthoughput, reproducible RNA sequencing has unravelled complex gene networks underlying (a) biotic stress response mechanisms in various agricultural crops. Through previous Non Assistance Cooperative Agreement projects, we have successfully employed RNA-seq to identify genes induced in boll pericarp and immature cottonseed in response to Aspergillus (A.) flavus infection (Bedre et al., 2015). In the proposed project, we propose to employ RNAseq (including small RNAseq) strategy in corn. As A. flavus is primarily a saprophytic fungus where its deleterious effects are highly environment-dependent, we propose to investigate the expression of candidate genes and miRNAs using near-isogenic corn lines contrasting in their response to A. flavus resistance. This will help pinpoint candidate resistance associated genes/miRNAs in different pathways and networks. Plant binary transformation vectors containing selected candidate genes/miRNAs will be constructed and transformed to corn for transgenic development. The transgenic plants will be evaluated for resistance to A. flavus under laboratory, greenhouse and/or field conditions. Genes/miRNAs showing promising results will be target for future gene editing strategies. (Note: All transgenic research mentioned in this proposal will be conducted at the SRRC/USDA, New Orleans).