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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Cereal Crops Research » Research » Research Project #428315

Research Project: Net Form Net Blotch of Barley, Identification and Characterization of Host Resistance

Location: Cereal Crops Research

Project Number: 3060-22000-050-30-T
Project Type: Trust Fund Cooperative Agreement

Start Date: Mar 1, 2015
End Date: Feb 28, 2020

Objective:
Here we propose the identification and characterization of both NFNB resistance/susceptibility genes from the host as well as the corresponding virulence effectors from the pathogen in order to properly characterize the complexity of the host-pathogen interaction. Identification and characterization of this interaction from both the pathogen and host perspective will allow for the deployment of broad and durable resistance by allowing for the intelligent combination or elimination of genes through traditional breeding approaches and if necessary biotech approaches in the future.

Approach:
Segregating pathogen populations, like barley mapping populations, can be used to characterize traits of interest. In this pathogen population we are interested in characterizing the genetics of virulence with the eventual goal of isolation of the genes involved in the production of the virulence factors. We have crossed two P. teres f. teres isolates (6A and 15A) that produce virulence factors that target the barley 6H region. Isolate 6A induces disease on the cultivar Rika by interacting with rpt.r and isolate 15A induces disease on the cultivar Kombar by interacting with rpt.k, therefore, progeny from the genetic cross of 15A and 6A can be used to characterize the virulence that targets the 6H region in both Rika and Kombar. In the last year we have developed molecular markers to generate a genetic map for the characterization of pathogen virulence. Four major virulence loci have been identified including two conferring virulence on Kombar and two conferring virulence on Rika. These virulences correspond to the susceptibility genes on barley chromosome 6H. Using the current 15A × 6A genetic map in conjunction with additional next generation long read (PAC BIO) sequencing we will attempt to assemble the genomic regions around these virulence genes in order to identify candidates for validation. Validation and characterization of the candidate genes will be done by transformation of the genes into avirulent P. teres isolates as well as by site directed gene disruption in virulent isolates (Liu and Friesen 2012) followed by evaluation of the change in virulence of each transformed pathogen strain. Additionally, we would propose that we make new pathogen populations using the most virulent local (ND, MN, MT) isolates crossed with several less virulent isolates for the continued evaluation of virulence important to the ND barley growing region. We have initiated these crosses and will be generating populations soon. These populations will then be mapped using molecular markers similar to the 15A × 6A population mentioned above for the eventual characterization of pathogen virulence.