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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Cereal Crops Research » Research » Research Project #428201

Research Project: Characterization of Genes Governing Sensitivity to Host-Selective Toxins Produced by Necrotrophic Pathogens in Wheat

Location: Cereal Crops Research

Project Number: 3060-21000-038-03-I
Project Type: Interagency Reimbursable Agreement

Start Date: Feb 14, 2015
End Date: Feb 13, 2020

Objective:
Overall objective: To characterize the molecular and genetic bases of host-toxin interactions in the wheat-S. nodorum pathosystem. Specific objectives: 1. Determine structural diversity and natural variation among alleles of Tsn1 and Snn1. 2. Develop tools for the functional analysis of toxin sensitivity genes. 3. Isolate, validate, and characterize Snn3. 4. Determine the relative effects of compatible Tsn1-ToxA, Snn1-SnTox1, and Snn3-SnTox3 interactions in causing disease.

Approach:
1. Determine structural diversity and natural variation among alleles of Tsn1 and Snn1. Now that we have cloned Tsn1 and Snn1, we will conduct comparative sequence analysis of alleles in the diploid and tetraploid wheat progenitors to gain further understanding of the functional nature and evolution of these genes, and how necrotrophic pathogens subvert resistance mechanisms to cause disease. 2. Develop tools for the functional analysis of toxin sensitivity genes. We will transform Arabidopsis and rice with Snn1 and Tsn1 as potential tools to further elucidate Snn1-SnTox1 and Tsn1-ToxA biochemical pathways. We will also generate wheat near-isogenic lines possessing only Tsn1, only Snn1, neither gene, and both genes for RNAseq experiments to evaluate the extent of overlap in downstream pathway activation. 3. Isolate, validate, and characterize Snn3. Compatible Snn3-SnTox3 interactions are not dependent on light, and therefore may involve mechanisms and/or pathways different from those exploited by the Tsn1-ToxA and Snn1-SnTox1 interactions. Snn3 will be isolated by positional cloning, validated, and functionally characterized using chemically-induced knockout mutants. 4. Determine the relative effects of compatible Tsn1-ToxA, Snn1-SnTox1, and Snn3-SnTox3 interactions in causing disease. A segregating wheat population will be evaluated for disease caused by S. nodorum isolates that produce ToxA, SnTox1, and SnTox3 to determine the effects of each host-toxin interaction alone and in various combinations, which will shed light on the relative significance of these interactions in causing disease.