Study on the genetic variation among the progenies derived from disomic alien addition lines from an intersubgeneric cross between glycine max and g. tomentella

Disomic alien addition lines (DAALs, 2n=42) were generated from an intersubgeneric cross between Glycine max and its perennial relative G. tomentella. All the DAALs were nearly identical but had distinct morphology from either of the parents. In some DAAL rows, “off-type” plants were found as the result of the DAAL losing the extra pair of G. tomentella chromosomes, and the derived disomic progenies (2n=40) possess phenotypes that no longer resembled the progenitor DAAL or the parents. The objective of this research was to document the wide phenotypic and genetic variation among the DAAL-derived disomic progenies and to understand the source of phenotypic and genetic variation. In the replicated field study, greater phenotypic variation was documented and compared to previous study. Genotypic data identified genome-wide variation and the genetic distances ranged from 0.05 to 0.44 among the disomic progenies. The genetic variants found for three soybean traits: pubescence color, stem termination, and seed coat color were previously known, except for a novel grey pubescence allele. But whether this allele exists in other soybean accessions remains unknown. Three high protein lines derived from DAALs were used to create mapping populations for seed protein and oil concentration. LG12-7063 was found to carry QTLs for high seed protein concentration on chromosome 20 and 6. These regions have been reported in soybean before, and no evidence supported that the source to high seed protein originated from G. tomentella. While the DAALs lost the extra G. tomentella chromosomes at an average frequency of 4% from 2013 and 2016, deviant plants with recessive-to-dominant changes were found within rows that had a recessive phenotype at a rate of 0.7%. Genotypic data also showed that the deviants from progenitor with a recessive trait and off-types plants collected within DAAL rows were highly heterozygous, and the heterozygosity spread across at least seven chromosomes in the genome. This indicates that cross-pollination, which is high unusual among soybeans, could likely be the cause of both the off-type plants after the loss of the two G. tomentella chromosomes from the DAAL, as well as the recessive-to-dominant phenotypic changes to the deviants. However, this hypothesis requires further research to confirm