Evolutionary population structure model reveals pleiotropic effects of GmPDAT for seed oil- and size-related traits in soybean

Authors: LIU, J - Huazhong Agricultural University; ZHANG, Y - Nanjing Agricultural University; HAN, X - Huazhong Agricultural University; ZUO, J - Huazhong Agricultural University; ZHANG, Z - Zhengzhou University; SHANG, H - Zhengzhou University; Song, Qijian; ZHANG, Y - Huazhong Agricultural University

Submitted to: Journal of Experimental Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/1/2020
Publication Date: 9/14/2020
Citation: Liu, J.Y., Zhang, Y.W., Han, X., Zuo, J.F., Zhang, Z.B., Shang, H.H., Song, Q., Zhang, Y.M. 2020. Evolutionary population structure model reveals pleiotropic effects of GmPDAT for seed oil- and size-related traits in soybean. Journal of Experimental Botany. 71(22):6988-7002. https://doi.org/10.1093/jxb/eraa426.
DOI: https://doi.org/10.1093/jxb/eraa426

Interpretive Summary: Soybean seed oil content and seed size are important traits. Scientists have identified genes that control soybean seed oil content and seed size, but genes simultaneously controlling both traits have not been reported. In this report, we describe two genes, GmDAGAT1 and GmPDAT, close to each other in a 200 kilo-base pair region on chromosome 13 that are responsible for both seed oil synthesis and seed size changes in soybean. Modified soybean plants that express greater amounts of RNA from the two genes had significantly increased seed oil content and seed size, while plants with suppressed RNA expression had significantly decreased seed oil content and seed size. These results provide new knowledge of the genetic mechanisms controlling oil content and seed size in soybean and will facilitate the improvement of these traits by breeders and geneticists working at private and public sectors for the benefit of soybean farmers and consumers.

Technical Abstract: Soybean seed oil seed size are important traits related to seed quality and seed yield. However, few genes with pleiotropic and epistatic effects on those traits have been reported. We identified two loci in a 200 kb region on chromosome 13 that were associated with oil- and size-related traits based on a single trait and multi-traits analyses. The interaction of the candidate genes GmPDAT and GmDGAT1 close to the two loci was confirmed by molecular structure analysis and luciferase complementation image assay. The expressional level of GmPDAT in the four accessions with high oil content and large-seed size was significantly higher than that in the two accessions with low oil content and small seed size. Real-time PCR analysis showed significant expressional levels of GmPDAT between overexpression lines and RNAi lines. The lines with overexpression significantly increased seed linolenic acid content, oil content, seed length, seed width and 100-seed weight, while RNAi lines significantly decreased seed oil content, linolenic acid, seed thickness, and 100-seed weight. We also observed that genome-wide association studies had higher power using evolutionary population structure than population structure of Q matrix. This result provides a new approach of identifying genes with pleiotropic and epistatic effects.