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ARS Home » Midwest Area » St. Paul, Minnesota » Plant Science Research » Research » Research Project #434405

Research Project: Epidemiology of Bacterial Stem Blight of Alfalfa and Development of Disease Resistance

Location: Plant Science Research

Project Number: 5062-12210-004-25-A
Project Type: Cooperative Agreement

Start Date: Oct 1, 2017
End Date: Jul 31, 2021

Cooperator will work with ARS in investigating the epidemiology of bacterial stem blight disease of alfalfa. Assays will be developed to determine bacterial pathogen (Pseudomonas syringae) populations on the surface and interior of plants over time and with crop management. The effects of crop chemicals on microbes will also be assessed.

Plant samples will be solicited from areas in which the disease is found for symptom evaluation and isolation of the pathogen. Leaves, stem internodes, and stem nodes will be processed separately to determine the primary location of P. syringae on alfalfa foliage. Positive colonies will be collected and stored in 20% glycerol at -80°C for characterization of genetic and pathogenic diversity. Pathogen genetic diversity will be assessed using DNA fingerprinting and gene sequences. Strains tagged with fluorescent marker genes will be used to follow pathogen invasion in resistant and susceptible plants. Expression of bacterial and host genes during pathogen invasion of resistant and susceptible plants will be measured to identify genes critical for disease to occur. Plants developed with mutated susceptibility genes will be tested for disease resistance and pathogen dynamics measured.