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United States Department of Agriculture

Agricultural Research Service

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Location: Sunflower and Plant Biology Research

Project Number: 3060-21000-039-09-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Jul 1, 2011
End Date: Jun 30, 2016

The overall goal of the proposed project is to improve Sclerotinia stalk rot resistance in the cultivated germplasm. Specific objectives are to: 1. Pre-breed novel Sclerotinia resistance from wild annual species of H. argophyllus, H. debilis, H. praecox, and H. petiolaris into cultivated sunflower, and develop an advanced backcross population for QTL mapping. 2. Investigate inheritance of Sclerotinia resistance in introgressed lines. 3. Develop, deploy, and validate a SNP marker resource for Sclerotinia stalk rot resistance from the results of our previous project.

Our approach has three parts. First, we will develop pre-breeding germplasm populations for genetic mapping and germplasm release. We have already developed eight BC2 populations from the crosses of HA 89 with resistant plants selected from H. argophyllus, H. debilis, H. praecox, and H. petiolaris. We will continue to evaluate Sclerotinia resistance in BC2F1 and BC2F2 populations in greenhouse trials in 2011 and identify resistant introgressed lines. We will also develop an advanced backcross mapping population from a cross of HA 89 (susceptible parent) with H. argophyllus (PI 494573, resistant parent) for molecular genetic mapping of Sclerotinia stalk rot resistance QTL. The BC2F2-derived population will be evaluated for host plant resistance to Sclerotinia stalk rot in the field, and will be interrogated with SSR markers in future years. Second, we will follow donor segment introgressions with genetic markers. Five-hundred sunflower SSR markers selected from sunflower genetic maps will be used to screen the polymorphism between HA 89 and wild annual species in order to monitor the introgressed traits in cultivated sunflower. Markers of introgressed zones of H. argophyllus, H. debilis, H. praecox, and H. petiolaris in the resistant lines are assumed to be good candidates to identify the segments carrying stalk rot-resistant QTLs. Third, we will use SNP markers associated with Sclerotinia resistance, discovered in our previous project, to improve a population of maintainer (B-line) sunflower with marker-assisted recurrent selection. This will also function to validate the utility of the markers. An oligonucleotide pool assay (OPA) will be developed and released based on our previous project’s results. The OPA will be used to conduct 3 cycles of recurrent selection. After the three cycles are complete, we will use field testing for stalk rot resistance to determine progress using markers versus foregoing the use of markers and proceeding using standard pedigree selection.

Last Modified: 10/15/2017
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