Construction of an Overexpression Library for Chinese Cabbage Orphan Genes in and Functional Analysis of -Mediated Flowering Delay.

Orphan genes (), which are unique to a specific taxon and have no detectable sequence homology to any known genes across other species, play a pivotal role in governing species-specific phenotypic traits and adaptive evolution. In this study, 20 of Chinese cabbage (, ) were transferred into by genetic transformation to construct an overexpression library in which 50% of the transgenic lines had a delayed flowering phenotype, 15% had an early flowering phenotype, and 35% showed no difference in flowering time compared to control plants. There were many other phenotypes attached to these transgenic lines, such as leaf color, number of rosette leaves, and silique length. To understand the impact of on delayed flowering, , which showed the most significantly delayed flowering phenotype, was chosen for further analysis, and was renamed (). In , the expression of key flowering genes, including and , significantly decreased, and and expression increased. GUS staining revealed promoter activity mainly in the roots, flower buds and leaves. qRT-PCR showed that primarily functions in the flowers, flower buds, and leaves of Chinese cabbage. BR4 is a protein localized in the nucleus, cytoplasm, and cell membrane. The accelerated flowering time phenotype of was observed under gibberellin and vernalization treatments, indicating that regulates flowering time in response to these treatments. These results provide a foundation for elucidating the mechanism by which regulate delayed flowering and have significance for the further screening of bolting-resistant Chinese cabbage varieties.