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United States Department of Agriculture

Agricultural Research Service

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Research Project: Characterization and Validation of Two Distinct Mechanisms for Partial Resistance to Sclerotinia Sclerotiorum in Pea

Location: Sunflower and Plant Biology Research

Project Number: 3060-21220-031-04-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Jun 1, 2014
End Date: Dec 31, 2018

The objective of this proposal is to characterize and optimize the screening of two distinct mechanisms of resistance to S. sclerotiorum in pea. For this purpose a detached stem assay technique will be developed to isolate the nodal transmission inhibition (NTI) resistance phenotype, and the resistance reaction of 90 PI accessions identified through a previously funded SI project will be verified to possess either lesion expansion inhibition or NTI using the detached stem assay. The nature of inhibited growth through the node will be investigated. The refined screening methods will be applied to F7-derived mapping populations and to verify the presence of QTL, and enhance the Pisum genetic map with SSR and SNP markers based on the reaction between pea and S. sclerotiorum. New markers will be applied to selection of resistant segregants among breeding populations being developed.

Screening procedures will be optimized to verify two forms of partial resistance to S. sclerotiorum in pea, lesion expansion inhibition (LEI) and nodal transmission inhibition (NTI), using a detached stem screening method. One set of 5 internodes of equal length and weight of a single PI line and another set of 5 internodes with node of same line will be tested with S. sclerotiorum to quantify the time required for S. sclerotiorum to pass through the node and isolate the nodal transmission inhibition resistance phenotype for all 90 PI lines. The optimized screening procedures will be applied to two mapping populations to further investigate and validate QTL for LEI and NTI in recombinant inbred lines (RILs) derived from the crosses Lifter/PI240515 and PI169603/Medora. Candidate SSR markers will be designed using sequence data obtained from partially resistant line PI240515 and susceptible line Lifter after infection with S. sclerotiorum, and run on mapping populations to identify closely linked markers to QTL associated with partial resistance.

Last Modified: 10/19/2017
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