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ARS Home » Midwest Area » West Lafayette, Indiana » Crop Production and Pest Control Research » Research » Research Project #432624

Research Project: Molecular Mechanisms of Host-Fungal Pathogen Interactions in Cereal Crops

Location: Crop Production and Pest Control Research

Project Number: 5020-21220-019-00-D
Project Type: In-House Appropriated

Start Date: Apr 2, 2017
End Date: Apr 1, 2022

Objective:
Objective 1: Identify candidate genes expressed by the host and fungal pathogens during resistant, susceptible and non-host interactions to elucidate mechanisms of host resistance of wheat, corn and barley. Sub-objective 1a. Identify genes expressed by hosts containing different resistance genes to identify the mechanisms involved in each resistance response. Sub-objective 1b. Identify genes expressed by the pathogens during different growth conditions that are involved in survival and pathogenicity. Objective 2: Determine whether selected genes function in fungal resistance responses by virus-induced gene silencing (VIGS) in wheat, and test if the best candidates confer improved resistance in transgenic plants. Sub-objective 2a. Utilize BSMV-VIGS to assess function of candidate genes in FCR and Septoria leaf blotch resistance. Sub-objective 2b. Attempt to engineer FCR, FHB or STB resistance in transgenic wheat utilizing genes confirmed in VIGS analysis. Objective 3: Analyze multiple fungal genomes to identify effectors and other biologically important genes involved in pathogenicity on wheat and corn. Objective 4: Determine the effectiveness of Host-Induced Gene Silencing (HIGS) to control Septoria and Fusarium diseases in wheat. Objective 5: Refine the map locations of genes for resistance to Septoria diseases in wheat and fungal diseases in corn to identify tightly linked molecular markers for marker-assisted selection in cereal improvement programs. Sub-objective 5a. Identify molecular markers tightly linked to the Stb2 and Stb3 resistance genes in wheat. Sub-objective 5b. Identify molecular markers linked to resistance genes in corn.

Approach:
Diseases caused by fungal pathogens pose significant economic threats to grain crop production. Currently, little is known about the molecular and genetic mechanisms that govern host resistance and fungal virulence in wheat. Research objectives and approaches in this project focus on identifying genes expressed by the host and the fungal pathogens during infection. The primary subjects of research will be septoria tritici blotch (STB) and Fusarium head blight (FCHB) and crown rot (FCR) of wheat. We will utilize RNA sequencing to identify wheat genes expressed during different types of resistance responses and fungal genes involved in pathogenicity and other important biological processes. Some of the host materials will include recently developed isogenic lines for resistance genes against STB. These genes are on different wheat chromosomes and the isogenic lines will allow us to test the hypothesis that they use different mechanisms for resistance. We will analyze non-host resistance responses in interactions between barley and wheat inoculated with Mycosphaerella graminicola and Septoria passerinii, respectively. Gene function in the pathogens will be confirmed by generating knockout mutants and testing for phenotype and in the host by Virus-Induced Gene Silencing (VIGS). We also will use comparative genomics of resequenced isolates to identify essential genes in M. graminicola and will use these plus others identified from the RNA-seq experiments for both pathogens to identify genes that can be targeted for Host-Induced Gene Silencing (HIGS) to increase the level of resistance in wheat. Additional objectives are to develop a CRISPR/Cas9 system for M. graminicola and to do fine-scale genetic mapping for developing additional molecular markers linked to the resistance genes. Successful completion of the objectives will contribute to the basic understanding of diseases caused by plant-pathogenic fungi and will provide clues about potential targets for genetic modification of the crop to prevent or circumvent damage resulting from fungal pathogens.