Selection of GmSWEET39 for oil and protein improvement in soybean

• DOI: 10.1371/journal.pgen.1009114
• Publication Date: 2020-11-11T18:44:52Z
• Authors: Hengyou Zhang; Wolfgang Goettel; Qijian Song; He Jiang; Zhenbin Hu; Ming Li Wang; Yong-qiang Charle...
• Keywords: 2. Zero hunger; 0303 health sciences; Monosaccharide Transport Proteins; Glycine max; Quantitative Trait Loci; Chromosome Mapping; QH426-470; Plant Proteins, Dietary; Polymorphism, Single Nucleotide; Plant Breeding; 03 medical and health sciences; Haplotypes; North America; Seeds; Genetics; Plant Oils; Genome, Plant; Research Article; Genome-Wide Association Study; Plant Proteins

Soybean [Glycine max(L.) Merr.] was domesticated from wild soybean (G.sojaSieb. and Zucc.) and has been further improved as a dual-use seed crop to provide highly valuable oil and protein for food, feed, and industrial applications. However, the underlying genetic and molecular basis remains less understood. Having combined high-confidence bi-parental linkage mapping with high-resolution association analysis based on 631 whole sequenced genomes, we mapped major soybean protein and oil QTLs on chromosome15 to a sugar transporter gene (GmSWEET39). A two-nucleotide CC deletion truncating C-terminus ofGmSWEET39was strongly associated with high seed oil and low seed protein, suggesting its pleiotropic effect on protein and oil content.GmSWEET39was predominantly expressed in parenchyma and integument of the seed coat, and likely regulates oil and protein accumulation by affecting sugar delivery from maternal seed coat to the filial embryo. We demonstrated thatGmSWEET39has a dual function for both oil and protein improvement and undergoes two different paths of artificial selection. A CC deletion (CC-) haplotype H1 has been intensively selected during domestication and extensively used in soybean improvement worldwide. H1 is fixed in North American soybean cultivars. The protein-favored (CC+) haplotype H3 still undergoes ongoing selection, reflecting its sustainable role for soybean protein improvement. The comprehensive knowledge on the molecular basis underlying the major QTL andGmSWEET39haplotypes associated with soybean improvement would be valuable to design new strategies for soybean seed quality improvement using molecular breeding and biotechnological approaches.