Wheat MADS-box gene TaSEP3-D1 negatively regulates heading date

The MADS-box gene plays an important role in regulating plant growth and development. In this study, a SEP3-like MADS-box gene TaSEP3-1 was isolated from bread wheat. The expression patterns of the three homoeologs TaSEP3-A1, TaSEP3-B1, and TaSEP3-D1 were similar, and higher expression levels were detected in floral organs and developing kernels. TaSEP3-D1 was located in the nucleus and cytoplasm and possessed transactivation activity in yeast. Homoeolog sequence polymorphism analysis identified four, three, and four haplotypes of TaSEP3-A1, TaSEP3-B1, and TaSEP3-D1, respectively, and the haplotypes of TaSEP3-D1 had larger effects on agronomic traits than those of TaSEP3-A1 and TaSEP3-B1. D1_h4, significantly associated with heading date, plant height, and other yield-related traits, was the favored haplotype of TaSEP3-D1. Transgenic wheat genotypes overexpressing TaSEP3-D1 exhibited delayed heading and reduced plant height, indicating a role in regulating heading date and plant development. These results shed light on the role of TaSEP3-D1 in wheat plant development. The favored haplotype of TaSEP3-D1 can be applied in breeding to improve plant architecture and yield in wheat.