Orphan gene positively regulates bolting resistance through the vernalization pathway in Chinese cabbage.

Orphan genes () are unique to the specific species or lineage, and whose homologous sequences cannot be found in other species or lineages. Furthermore, these genes lack recognizable domains or functional motifs, which make their characterization difficult. Here, we identified a   named () that could positively modulate bolting resistance. The expression of was developmentally regulated and the protein was localized to the cell membrane. overexpression not only markedly delayed flowering time in transgenic plants, but substantially affected the development of leaves and flower organs. Flowering repressor gene was significantly up-regulated transcribed in overexpression lines, while and expression was decreased. In addition, the expression was enhanced in bolting-resistant type Chinese cabbage and was reduced in non-resistant type. Moreover, chilling stress inhibited the expression levels. Overexpression of also delayed flowering time in Chinese cabbage. In vernalized Chinese cabbage overexpression plants, and were significantly down-regulated, while was substantially up-regulated. Key floral factors, including three , two , and four were down-regulated. The expression changes of these key genes were consistent with the delayed flowering phenotype of Chinese cabbage overexpressing plants. Thus, we predicted that may predominantly function the vernalization pathway. Our findings propose that the   acts as a novel modulator of flowering time in Chinese cabbage, which provides a new insight on the breeding of varieties that are resistant to bolting.