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.
The objectives of the this research are to screen germplasm lines for resistance to Phomopsis seed decay (PSD) of soybean; to breed high-yielding resistant cultivars and germplasm lines for North Central and Southern U.S.A. soybean productions by incorporating new resistant genes and alleles; and to develop new and rapid screening tools that are correlated with the field screening method for measurement of plant resistance. To identify new sources of soybean lines resistant to PSD, field screening of 135 selected soybean germplasm lines representing 28 worldwide origins and maturity groups 3-5 along with PSD resistant and susceptible checks were tested in Arkansas, Missouri, and Mississippi. Significant differences in seed infection by Phomopsis (P.) longicolla occurred among soybean lines with some lines having no PSD while others had levels as high as 90%. These differences between lines were reflected in visual seed quality and in seed germination. Based on the results from 2009, 42 lines were selected including resistant and susceptible checks for the 2010 field trials in Arkansas, Missouri, and Mississippi. By the end of May, 2010, field plantings in these three states for the PSD project have been completed. For the breeding and genetics studies, four advanced lines with PSD resistance derived from PI 80837 and PI 360841 were increased for seed in 2009. These lines showed some levels of seed shattering in the field, but the seed quality looked good. These early-maturing lines with PSD resistance will be evaluated for adaptation and yield in 2010. In addition, four F2 plant populations were derived from three different PSD resistance sources in attempts to pyramid different genes for PSD resistance. Five new crosses were made in the summer of 2009. These crosses are intended to incorporate PSD resistance from different sources into high yielding MG4-5 cultivars/lines adapted to the mid-south. Some of these populations can also be used for genetic studies and molecular mapping in the future. 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. ADODR used site visit, email and telephone conferences to monitor activities of the project.