Location: Crop Production and Pest Control Research
2023 Annual Report
Objectives
Objective 1: Conduct research to identify genetic loci involved in soybean seed protein and oil accumulation, characterize resource partitioning of the new soybean genotypes, and work with breeders to develop new germplasm incorporating genes for improved protein and oil traits.
Goal 1.A: Map genetic loci involved in soybean seed protein and oil accumulation.
Goal 1.B: Work with breeders to evaluate and incorporate new meal and oil traits.
Objective 2: Conduct research to elucidate pathogen biology, fungicide resistance, and virulence of Frogeye Leaf Spot disease, and identify novel host resistance to this threat to soybean production in the North Central region.
Hypothesis 2.A: Frogeye leaf spot in the northcentral states is caused by distinct clonal lineages consisting of both mating types and wide-spread-QoI resistance.
Hypothesis 2.B: C. sojina populations have high virulence diversity.
Hypothesis 2.C: Low-level sexual recombination occurs in C. sojina.
Objective 3: Conduct field and greenhouse research evaluations and statistical analyses to collect breeding-related data, and report results on testing of public sector soybean breeding lines evaluated in the Uniform Soybean Tests – Northern Region.
Goal 3: Evaluate advanced public breeding lines for agronomic performance, disease resistance and quality traits throughout the northcentral U.S. and Canada.
Approach
Objective 1:
Genes involved in soybean seed protein and oil accumulation will be isolated through phenotypic screening of seed composition traits. Mapping populations will be developed to isolate and characterize genes conferring improved composition phenotypes. Environmental and developmental characteristics will be examined in protein:oil mutants to further understand the control of resource partitioning in the seed. New and existing genes will be combined and evaluated for their utility to provide soybean breeders with new composition traits for current and future needs.
Objective 2:
Cercospora sojina isolates will be collected from soybean fields in Indiana and other states. The isolates will be examined for resistance to QoI fungicides by amplifying and sequencing their mitochondrial cytochrome b gene. Their mating types will be determined by amplifying Mat1-1 and Mat1-2 genes using gene-specific primers. The pathogen population will be genotyped using a panel of single nucleotide polymorphism markers. Isolates representing different genotypes will be used to inoculate a set of 14 soybean differentials to determine their virulence. Isolates with different mating type genes will be used to co-inoculate soybean. Pathogen will be re-isolated from plant tissue and genotyped to determine whether sexual recombination occurred.
Objective 3:
Public soybean breeders submit their soybean breeding lines for evaluation of agronomic performance, disease resistance and quality traits. Entries are separated by maturity group and assigned to either the ‘Preliminary Tests’ or the ‘Uniform Tests’. Seeds of each entry, along with those of the standard reference varieties, are packaged and distributed to collaborators throughout the U.S. and Canada for evaluation. In addition, entries will be evaluated at multiple locations in Indiana. Harvested seeds will also be tested for quality traits. Collaborators submit performance data from their locations to ARS after harvest. This data is compiled and analyzed by this research group following established protocols. The results will be published in an annual report book and online.
Progress Report
This is the first report for this new project started in May 2023 and continues research from the previous project, 5020-21000-008-000D, “Genetic Enhancement of Seed Quality and Plant Health Traits, and Designing Soybeans with Improved Functionality”. Please see the report for the previous project for additional information.
For Objective 1, Goal 1.A, we have planted four populations to map genes for high protein and one population to map a gene for high oil. We developed new polymerase chain reaction (PCR)-based markers to map a high protein gene on chromosome 10, and added more individuals to that mapping population to increase resolution. We profiled seed development in twelve of the high protein mutants grown in controlled conditions (growth chambers) to determine if there are measurable changes in gene expression shared by high protein lines. For Goal 1.B, we are moving genes for high oleic acid and low raffinose and stachyose into higher yielding germplasm for release. We will deploy molecular markers in the summer of 2023 to select double mutants after the first round of crosses, and evaluate seed composition in these lines after harvest in October.
For Objective 2, Goal 2.A, we collected soybean leaf samples and received some samples through collaborations. A total of 234 samples were collected. Leaf samples were placed in a moist chamber for 48-72 hours. Single-conidial isolates were obtained. These isolates showed typical morphology of Cercospora sojina, the causal pathogen of frogeye leaf spot. We are in the process of extracting DNA from these isolates to amplify the internal transcribed region of ribosomal RNA gene for molecular identification.
For Goal 2.B, we increased 14 soybean lines carrying different loci for resistance to differentials for frogeye leaf spot (differentials). In addition to the 12 previously reported differentials, Lincoln (PI 548362), Blackhawk (PI 548516), Peking (PI 548402), Richland (PI 548406), Kent (PI 548586), Lee (PI 548656), Hood (PI 548980), Tracy (PI 548983), S-100 (PI 548488), Palmetto (PI 548480), CNS (PI 548445), and Davis (PI 553039), we also included Bao Gong Dou (PI 594774) and Da dou (PI 594891). The last two lines were recently reported to confer complete/near-complete resistance to frogeye leaf spot. These lines were increased in 2022 and again in 2023. Lincoln, Blackhawk, Peking, Richland, Kent, and S-100 were increased in West Lafayette, Indiana. The other lines belong to late maturity groups and cannot produce mature seeds here. They were increased by fellow ARS scientist Dr. James Smith in Stoneville, Mississippi, through collaboration.
For Objective 3, we completed the harvest of 2022 field trials and seeds were evaluated for nutritional composition (protein, oil, and sugar contents, and amino acid composition). We collected data from all 20 collaborators, compiled and analyzed the data. The results were published in the report book “The Uniform Soybean Test Northern Region 2022”. Hard copies were sent to all collaborators. Electronic copy is freely available online. In 2022, 35 soybean varieties evaluated in this program were publicly released or licensed to private companies. For 2023 test, we organized the coordination meeting in February 2023, finalized the experimental design, collected seeds from all collaborators, packaged and distributed seeds to all test locations. We grew field trials in three locations in Indiana. Planting was completed on time. We also screen the soybean breeding lines for resistance to frogeye leaf spot and this task is on schedule.
Accomplishments
