Utilization of natural hybridization and intra-vultivar variations for improving soybean yield, seed weight and agronomic traits

Authors: JIANG, GUOLIANG - Virginia State University; MIREKU, PATRICK - Virginia State University; Song, Qijian

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/5/2024
Publication Date: 9/2/2024
Citation: Jiang, G., Mireku, P., Song, Q. 2024. Utilization of natural hybridization and intra-vultivar variations for improving soybean yield, seed weight and agronomic traits. Crop Science. https://doi.org/10.1002/csc2.21342.
DOI: https://doi.org/10.1002/csc2.21342

Interpretive Summary: Soybean is generally considered a highly self-pollinating plant, but cross-pollination occasionally occurs. In plant breeding, artificial hybridization is the most common method to generate genetic variation for selection of desired traits. Natural hybridization is often overlooked in breeding practices for self-pollinating species. Intra-variety variation occurs due to underlying variation, genetic heterogeneity, and mutant alleles in improved varieties. Both natural hybridization and intra-variety variation may provide breeders with opportunities for soybean variety improvement. To demonstrate this, researchers from Virginia State University and the U.S. Department of Agriculture Agricultural Research Service (USDA-ARS) conducted field trials over four crop seasons on 17 source materials and 78 breeding lines from natural hybridization and intra-variety variation to evaluate yield and related agronomic traits. They found that many of the new lines showed significant improvements in one or more traits of yield, seed weight, and other agronomic traits compared to the source materials. They demonstrated that both segregation and intra-variety/intra-line variation generated by natural hybridization can be used to improve important traits in soybean and will help breeders develop breeding strategies.

Technical Abstract: Soybean (Glycine max) is a highly self-pollinated species, but cross-pollination occasionally occurs and variations within cultivars can be observed under certain conditions. To explore the potential uses of natural hybridization and intra-cultivar/advanced line variations, 78 of breeding lines derived from the segregants of natural hybridization and the intra-cultivar/line variations and their 17 source cultivars/lines were evaluated over four crop seasons for yield, seed weight and other agronomic traits. All the lines were also genotyped using BARCSoySNP6K assays to compare the genetic similarities between the new lines and the source genotypes. The genotypic differences, year effects and genotype x year interactions were significant for all the traits among the breeding lines. The broad-sense heritability of the traits was estimated to be 67.22 – 98.80%, suggesting that the traits were mainly affected by genetic factors. Yield was negatively correlated with seed weight, plant height and pod shattering. Seed weight was significantly but weakly genetically correlated with days to flowering, plant height, lodging or shattering. Lodging was genetically correlated with growth stages, plant height and shattering. Compared with the source materials, yield of 34 breeding lines exceeded by more than 5%. Seed weight increased significantly in 24 lines, and 11 lines showed improvements in both seed weight and yield, although there was a negative correlation between these two traits. In addition, 36 and 29 lines showed a shortened period of flowering and maturity, respectively. Plant height of 20 lines decreased by more than 8.5 cm. Genotypic matching rate between the new lines and the source materials varied from 48.86% to 99.90%. These results demonstrated that segregations resulting from natural crossing and intra-cultivar/line variations could be used to improve important traits in soybean.