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United States Department of Agriculture

Agricultural Research Service

Research Project: Screening Germplasm and Breeding for Resistance to Phomopsis Seed Decay in Soybean (Usb Project No. 9261)

Location: Crop Genetics Research Unit

2012 Annual Report


1a.Objectives (from AD-416):
Screen untaggeed germplasm lines for resistance to Phomopsis seed decay (PSD) of soybeans. Breed high-yielding resistant cultivars and germplasm lines for North Central and southern U.S. soybean production regions by incorporating new resistant genes and alleles. Develop new and rapid screening tools that are correlated with the field screening method for measurement of plant resistance.


1b.Approach (from AD-416):
Use field and laboratory approaches to identify sources of Phomopsis resistance. During the first year of this project, 123 selected soybean germplasm lines collected from 28 countries, and breeding lines and cultivars from Southern U.S. will be screened in the fields of three states (Arkansas, Mississippi, and Missouri). Visual scoring and seed assay in laboratories on the incidence of the PSD pathogen will be performed. The top 10-15 resistant lines will be selected for the second year field trials with replicated inoculation and non-inoculation tests using local isolates from each state. Winter nursery facilities in Argentina and Costa Rica contracted by the University of Arkansas will be available to the team to speed up the process of generation advances. Mapping populations will be developed and molecular markers will be identified for use in marker-assisted selection.


3.Progress Report:

A total of 135 selected soybean germplasm lines representing 28 countries and maturity group (MG) III, IV, and V were field screened by natural infection in 2009 in three states, Arkansas, Mississippi and Missouri. Seeds were harvested from each plot when the plants were mature and tested for percent seed infected by Phomopsis spp., germination rate, and visual quality. Based on the results from seed assays from three states in 2009, 42 lines (14 lines for each maturity groups II, IV, and V) including the most resistant and susceptible lines were selected and planted in 2010 and 2011 at three states with inoculation and non-inoculation treatment. In Mississippi, field trials also were setup to test 14 selected Maturity Group (MG) V Plant Introductions (PI)s. At least eight PIs with PSD resistance are identified. In addition, field experiment were conducted to determine the impact of a foliar application of the herbicide Cobra and an infurrow and foliar applications of the fungicide Quadris on Phomopsis seed decay (PSD) at Missouri. Seed from each plot were harvested for seed assays.

In the effort of breeding for PSD resistance, four F2 plant populations were derived from three different PSD resistance sources in attempts to pyramid different genes for PSD resistance, five cross combinations were made to incorporate PSD resistance from different sources into high yielding MGIV-V cultivars/lines adapted to the mid-south, eight new cross combinations were made to incorporate PSD resistance into high yielding cultivars or breeding lines, twenty new F2:3 lines derived from R00-1194F x PI 80837 were evaluated in the progeny rows in 2011, and 71 F3:4 lines derived from UA 4910 x PI 80837 were grown for breeding selections in Fayetteville, AR.

Some research is being done in cooperation with scientists at other institutions: University of Arkansas (Specific Cooperative Agreement, subordinate project 6402-21220-010-09S), and University of Missouri (Specific Cooperative Agreement, subordinate project 6402-21220-010-10S). Separate reports summarize work completed under these agreements.

In summary at least eight Germplasm lines with PSD resistance are identified. PI 424324B was the best PSD-resistant line. Breeding lines and populations are being developed. Protocols for resistance screening based on seed assays are developed. This research was reported in Agricultural Research and USDA-ARS Newsmakers. One invited peer-reviewed book chapter, six peer-reviewed manuscripts, and 7 abstracts related to the research on PSD were published. Also, twelve oral presentations (6 international) and 7 poster presentations were made.

ADODR monitored the project progress by telephone calls, on-site cooperator/ARS meetings, site visits, email communications, discussions at professional conferences/meetings, annual meeting, and review of four quarterly progress/accomplishment reports each year. ADODR also submitted a final report to United Soybean Board in May 2012. This research was reported in Agricultural Research and USDA-ARS Newsmakers.


Last Modified: 10/21/2014
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