2025-10-31 中国科学院(CAS)
＜関連情報＞
- https://english.cas.cn/newsroom/research_news/life/202510/t20251031_1095176.shtml
- https://www.pnas.org/doi/10.1073/pnas.2508709122
栽培化で失われたPC08の天然対立遺伝子は、大豆の種子貯蔵タンパク質の蓄積に寄与する A natural allele of PC08 lost in domestication contributes to soybean seed storage protein accumulation
Shu Liu, Peichun Zeng, Dingyue Ban, +3 , and Xingliang Hou
Proceedings of the National Academy of Sciences Published:October 30, 2025
DOI:https://doi.org/10.1073/pnas.2508709122
Significance
As the demand for soybean protein rapidly grows, higher seed protein content is desired. Wild soybeans exhibit substantially higher seed protein level than elite cultivars, indicating a loss of storage protein during domestication. Here, we found a rare high protein allele of Protein Contributor 08 (PC08) from wild soybeans, as a contributor to high seed storage protein content. The allelic variation in the promoter led to increased expression of PC08, resulting in elevated seed abscisic acid (ABA) content and promoted seed protein accumulation. This high-protein allele of PC08 derived from wild soybeans was not retained during domestication, which is a valuable genetic resource for soybean quality improvement in the future.
Abstract
Soybean serves as a critical source of plant-based protein for both livestock and human nutrition, making seed protein content a key agronomic trait. However, modern soybean cultivars exhibit reduced seed protein content compared to their wild relatives, as a consequence of domestication and historical selection that favored yield over nutritional quality. Thus, genetic improvement of seed protein is highly desired in soybean breeding, while numerous genetic loci associated with this trait remain uncharacterized. Here, we report Protein Contributor 08 (PC08), identified through a genome-wide association study, as a key regulator of seed storage protein accumulation. PC08 encodes a homolog of the 9-cis-epoxycarotenoid dioxygenase 5 enzyme, a rate-limiting enzyme in abscisic acid (ABA) biosynthesis, and is highly expressed during seed development. A nucleic acid T and A (TA)-rich insertion within the PC08 promoter region (designated as PC08Ins) enhances transcriptional activity, leading to elevated PC08 expression. Transgenic evidence confirmed its positive regulatory role in seed protein accumulation, mechanistically linked to increased ABA biosynthesis in developing seeds. ABA upregulation activates downstream pathways that promote storage protein synthesis. Population genetic analyses revealed that the PC08Ins, which confers high protein content, exclusively exists in wild soybean populations and was entirely absent after domestication. Introgression of PC08Ins into the elite cultivar Hei Nong 35 significantly increased seed protein content. These findings highlight a domestication-eroded allele with untapped potential for modern breeding, offering a valuable genetic target to enhance soybean nutritional quality.
