|
内容記述 |
Soybean seeds accumulate approximately 40% protein and are widely used as a raw material in the food and feed industries. Historically, soybean breeding has been constrained by a negative correlation between seed protein concentration and yield. This trade-off has been attributed to limitations in assimilate supply during seed filling, whereby an increase in seed number per unit area dilutes the carbon and nitrogen available per seed, resulting in reduced seed protein concentration. To elucidate the underlying mechanisms, a high seed protein content mutant, hp1, identified from an EMS-induced mutant library, was subjected to next-generation sequencing (NGS)–based bulk DNA analysis. This analysis led to the identification of the causal gene, GmSWEET10b, which encodes a sugar transporter that facilitates sugar allocation to the embryo. The hp1 mutant harbors a mutation at the splice site between the third intron and the fourth exon of GmSWEET10b, resulting in retention of the third intron and a consequent frameshift mutation. Using amplicon sequencing methods, two additional nonsense mutants and one splice-site mutant were identified from the soybean mutant library, all of which exhibited elevated seed protein content. While the seed protein content of the wild-type cultivar ‘Enrei’ was 46%, that of hp1 reached 52%, and the other mutants also showed significantly higher seed protein content than ‘Enrei’, accompanied by a reduction in seed size. Introgression of the hp1 mutation into the ultra–high–protein soybean cultivar ‘Tomutan’ further increased seed protein content despite a reduction in seed size, demonstrating that the hp1 mutation can be utilized to enhance protein accumulation in soybean seeds. |
