Soybean (Glycine max L. Merr.), a globally critical oilseed and economic crop, stands as a primary source of high-quality protein for human consumption and animal feed alike. Among the agronomic traits shaping its productivity, seed size and the balance between oil and protein content are deemed pivotal-making the identification of genes governing these traits and the clarification of their molecular mechanisms essential for advancing high-yield, high-quality soybean varieties via molecular design breeding.
In a recent breakthrough, a research team led by Prof. HOU Xingliang from the South China Botanical Garden of the Chinese Academy of Sciences, has published their findings in Nature Communications. Through Genome-wide Association Studies (GWAS) and quantitative trait loci (QTL) mapping, the team pinpointed a Nuclear Factor-YA (NF-YA) gene located on chromosome 14, which they named Seed Weight 14 (SW14).
Functional analysis revealed that SW14 exerts a dual regulatory role: it positively boosts seed weight and protein content while negatively regulating oil content-all without impacting other key agronomic traits of the soybean plant.
Further investigations uncovered the molecular mechanism behind SW14's action. The gene interacts with GmLEC1a/b-soybean homologs of Leafy Cotyledon1 (LEC1), a core regulator of seed development. This interaction disrupts the formation of a non-canonical NF-Y complex, which normally consists of GmLEC1, GmNF-YC2, and GmbZIP67. By breaking down this complex, SW14 inhibits the transcriptional activation process mediated by GmLEC1-a process critical to seed development.
Additional genetic analysis provided further insights: a superior allele of SW14, designated SW14H3, was found to have undergone artificial selection during the domestication of soybeans. The researchers noted that this allele holds significant potential for improving soybean yield in agricultural applications.
The study received financial support from the National Key Research and Development Program of China, and the National Natural Science Foundation of China, among other sources.
