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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

Location: Crop Genetics Research Unit

2010 Annual Report


1a.Objectives (from AD-416)
(1) Screen soybean lines for resistance to Phomopsis Seed Decay (PSD). (2) Breed high-yielding resistant cultivars and germplasm lines for North Central and Southern U.S. soybean production regions by incorporating new resistance genes and alleles. (3) Develop new and rapid screening tools that are correlated with the field screening method for the measurement of plant resistance.


1b.Approach (from AD-416)
Phomopsis seed decay (PSD) of soybean is a major cause of poor quality and poor germination of soybean seeds in the United States, especially in the mid-southern U.S. This research will be focus on two sides of the disease equation:.
1)screening untapped (not yet tested for PSD resistance) 123 MG 3-5 germplasm lines collected from 28 countries, and.
2)breeding lines and cultivars from southern U.S. with resistance to PSD. This research will provide tools and potential new resistance genes to increase breeding efficiency for high-yield PSD resistant lines.


3.Progress Report

Determined in 2009 field tests at the University of Missouri the reaction of 45 MG III, 45 MG IV, and 45 MG V plant introductions (PI’s) to Phomopsis seed decay (PSD). Seeds from all plots were evaluated for visual appearance, percent germination, and percent seed infected by Phomopsis spp. The results show that the MG 3, 4, and 5 entries most susceptible to Phomopsis seed decay had 79%, 78%, and 83% of seed infected with Phomopsis spp., respectively. The percent of seed infected with Phomopsis spp. was less than 10% for 25 of 45 MG III lines, 6 of 45 MG IV lines, and 0 of 45 MG 5 lines tested. Two MG V lines tested had less than 20% seed infected with this pathogen. The University of Missouri secondly, determined in 2009 field tests affect of infurrow and foliar applications of the fungicide Quadris and a foliar application of the herbicide Cobra, and of select plant introductions on percent of seed infected with Phomopsis species. The results showed that the fungicide and herbicide applications did not affect the percent of seed infected with Phomopsis species. The project was monitored through emails, telephone calls, and site visits.


Last Modified: 4/20/2014
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