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United States Department of Agriculture

Agricultural Research Service

Research Project: MOLECULAR APPROACHES TO UNDERSTANDING HOST RESISTANCE AND PATHOGEN VARIABILITY FOR IMPROVING POTATO AND TOMATO DISEASE MANAGEMENT Project Number: 1275-21220-250-00
Project Type: Appropriated

Start Date: Feb 03, 2009
End Date: Apr 01, 2012

Objective:
Objective 1: Characterize genetic differences in isolates of plant pathogenic streptomycetes and Phytophthora using targeted PCR, markers, regional genome sequencing and biological assays. Sub-objectives: a. Characterize populations of Streptomyces causing common scab in the U.S., using PCR and regional genome sequencing of 16s ribosomal RNA genes and genes from the pathogenicity island. b. Identify and characterize genes and corresponding gene product proteins, peptides and other compounds produced by Streptomyces and Phytophthora that may contribute to pathogenicity. c. Identify critical components of pathogen genetic variability contributing to variation in severity of common scab and late blight. d. Identify critical components in the genetic variability of Phytophthora infestans which contributes to variation in disease severity. Objective 2: Characterize genetic differences in disease resistance of solanaceous hosts in response to Phytophthora and Streptomyces scabies. Sub-objectives: a. Characterize differences in gene expression in both hosts and pathogens to identify pathogenicity determinants, applying RT-PCR, microarray analysis, and functional genomics. b. Map genes for resistance to common scab onto potato chromosomes, and develop molecular markers for common scab resistance. Objective 3: Identify plant defense responses in tomato induced by the biocontrol agent F. oxysporum strain CS-20 and determine their contribution to observed biocontrol of Fusarium wilt? Other biocontrol-host-pathogen systems and biocontrol mechanisms will be included as time and resources permit, and as indicated by results. Objective 4: Identify and characterize genetic traits and gene expression related to biocontrol ability in the biocontrol fungus F. oxysporum strain CS-20. Objective 5: Determine the effects of phytopathogenic F. oxysporum and the biocontrol fungus F. oxysporum strain CS-20 on population sizes and root colonization of each other.

Approach:
Characterization of genetic differences in isolates of plant pathogenic Streptomycetes, Fusarium and Phytophthora will be performed using targeted PCR, markers, regional genome sequencing and biological assays. Populations of Streptomyces causing common scab in the U.S. will be characterized, using PCR and regional genome sequencing of 16S ribosomal RNA genes and genes from the pathogenicity island. Genes and corresponding gene product proteins, peptides and other compounds produced by Streptomyces, Fusarium and Phytophthora that may contribute to pathogenicity will be identified and characterized. Critical components of pathogen genetic variability contributing to variation in severity of common scab and late blight will also be identified. Mechanisms of biological control by non-pathogenic fusaria will be studied. Additionally, genetic differences in disease resistance of solanaceous hosts in response to Phytophthora and Streptomyces scabies are to be characterized, utilizing differences in gene expression in both hosts and pathogens to identify pathogenicity determinants, applying RT-PCR, microarray analysis, and functional genomics. Genes for resistance to common scab will be mapped onto potato chromosomes, and molecular markers for common scab resistance developed.

Last Modified: 10/24/2014
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