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United States Department of Agriculture

Agricultural Research Service

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Research Project: ENHANCING SOYBEAN FOR RESISTANCE TO SCLEROTINIA STEM ROT

Location: Sunflower Research

2012 Annual Report


1a.Objectives (from AD-416):
The long-term goal of this project is to develop soybean varieties or germplasm that have a high level of resistance to Sclerotinia stem rot. The short-term supporting objectives are: (1) further evaluate the advanced lines selected from a previous project and release the best lines as germplasm or varieties; (2) evaluate seven populations of F4 derived lines with resistance from five new resistant plant introductions (PIs) for resistance to Sclerotinia stem rot and agronomic traits; and (3) determine if reported QTLs associated with resistance to Sclerotinia stem rot are also associated with the resistance in the five new resistance sources.


1b.Approach (from AD-416):
For objectives 1 and 2, the lines will be evaluated in multiple locations in Michigan for yield and agronomic traits. The lines will also be evaluated for resistance to Sclerotinia stem rot in the greenhouse with the spray-mycelium method and/or drop-mycelium method developed by us. About 15% of the lines will be selected based on the greenhouse resistance to Sclerotinia stem rot, yield, and other agronomic traits. The selected lines will be evaluated in our disease nursery for resistance to Sclerotinia stem rot and yield under disease pressure. Five to 10 lines will be selected and tested in the Uniform Soybean Tests – Northern Region (19 locations in 10 northern US states and 1 Canadian province), for yield and other agronomic traits. The best 1-3 lines will be released to the public. For objective 3, the same seven populations evaluated for objective 2 will be genotyped with polymorphic SSR (simple sequence repeat) and SNP (single nucleotide polymorphism) DNA markers within 20 cM on either side of 34 reported QTLs for resistance to Sclerotinia stem rot. The DNA marker data and the disease resistance data obtained under objective 2 will be analyzed together to determine if the reported QTLs are also associated with the resistance in the five new resistance sources.


3.Progress Report:

This project was initiated on June 1, 2009, research is ongoing, and the overall goal of this project is to develop soybean varieties or germplasm that have a high level of resistance to Sclerotinia stem rot.

This continuing research is directed toward:.
1)further evaluating the advanced lines selected from a previous project and releasing the best lines as germplasm or varieties;.
2)evaluating populations of derived lines with resistance from five new resistant plant introductions (PIs) for resistance to Sclerotinia stem rot and agronomic traits; and,.
3)determining if reported QTLs associated with resistance to Sclerotinia stem rot are also associated with the resistance in the five new resistance sources. Progenies from crosses with different sources of Sclerotinia resistance were evaluated at different scales according to their generations and stages of selections in the breeding program. Four hundred seventy one F4:5 lines were evaluated at one location for maturity, lodging, and yield. One hundred fifty four F4:6 lines selected based on 2010 data were evaluated in 2011 at two locations for yield and other agronomic traits. Thirty one F4:7 lines were evaluated at eight locations for their agronomic performance and yield under natural disease pressure. The 31 F4:7 lines were also evaluated in an inoculated Sclerotinia disease nursery with other 43 advanced selections. The disease severity index (DSI) in the disease nursery ranged from 6.7% to 73.3% and the four most resistant lines with DSI less than the 10% threshold were among the 31 F4:7 lines derived from a Sclerotinia resistant parent.


Last Modified: 10/1/2014
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