Construction and evaluation of Brassica rapa orphan genes overexpression library

Orphan genes (<i>OGs</i>) are crucial for species-specific characteristics and stress responses and are restricted to a specific taxon. However, their functions within particular species are poorly understood. Previous research identified <i>OGs</i> in <i>Brassica rapa</i> (<i>BrOGs</i>). In this study, the <i>BrOGs</i> overexpression (BrOGsOE) library in <i>Arabidopsis thaliana</i> was constructed. Approximately 128 unknown functional <i>BrOGs</i> were selected from Chinese cabbage and were overexpressed. The analysis focused on the phenotypes of leaf morphology and flowering time against phenotypic differences between Chinese cabbage and <i>Arabidopsis</i>. Interestingly, 72.66% of the transgenic lines showed distinctive phenotypic changes. Chinese cabbage-specific features, including curved, hairy, upward or downward-curving leaves, serrated margins, and multiple leaves, were observed in the BrOGsOE lines. The <i>BrOGs</i> overexpression library was associated with numerous variations in flowering time, particularly delayed flowering. This suggested that the delayed flowering time caused by <i>BrOGs</i> may be associated with resistance to bolting seem in Chinese cabbage. Furthermore, the results of stress treatment of 24 BrOGsOE lines with no apparent significant phenotypes suggested that a number of <i>BrOGs</i> have both general and specific functions against environmental and pathogenic stress. The findings of this study provide a comprehensive overview of the roles of <i>BrOGs</i>, emphasizing their significance as a resource for identifying positive genes associated with species-specific characteristics and stress responses and offering a solid foundation for the functional analysis of <i>BrOGs</i>.