Update:
refer to final report

1) Identify genes and/or genomic regions (i.e., small DNA fragments) underlying yield component traits such as pod numbers per node, node numbers per plant, and seed sizes and plant architecture traits such as branching angles and leaf shapes.

Progress: Using resources/materials produced previously and through this project, and the phenotyping (traits) data generated in the Agronomy farm, as well as genotyping data (DNA markers), we have (i) identified a key QTL/gene controlling soybean branching angle/canopy coverage; (ii) defined a major QTL region underlying soybean seed number per pod to an ~800-kb chromosomal fragment; (iii) identified a major QTL associated with soybean leaf shape. These significant progress has laid a solid foundation for development of high-yield soybean varieties with enhanced yield components and ideal plant architecture for high yield. Seed size was found to be controlled with several minor effect QTLs, and will not be further explored. We we are developing additional markers for finer-scale localization of the QTL associated with seed size and are in the process of validating candidate genes for branching angle/ canopy coverage, and leave shape.

2) Develop molecular markers for implementing marker-assisted selection for yield-related traits in breeding programs.

Progress: We have developed molecular markers based on the sequence variation in the candidate genes and/or the QTL regions under those specific yield component traits. Some of these markers have been used to track the relevant genes and assist to identify additional genes associated with these traits. This approach has proven to be very powerful in dissecting complex traits each controlled by multiple genes. We have also started to use these markers to precisely genotype/validate a set of soybean varieties that represent soybean genetic diversity. These accessions have been previously either re-sequenced or genotyped by using 50K SNP markers by soybean research community, and thus allows us leverage publicly available data to maximize our capacity for gene/allele discovery and utilization of these genes/alleles for germplasm enhancement.

3) Select and evaluate experimental lines with enhanced yield potential

Progress: We have planted some of the high-yielding experimental lines derived from crosses between elite soybean varieties and over 10 wild soybean (the progenitor species of cultivated soybeans) accessions, and measure yield components and branching angles. Their relative contribution to yield potential need to be further evaluated.