Overexpression of the gene in alters the cotyledon morphology and increases rosette leaf number.

Background: The unique 'mandarin jacket' leaf shape is the most famous trait of and this characteristic gives aesthetic and landscaping value. However, the underlying regulatory mechanism of genes involved in the leaf development of has remained unclear.

Methods: Based on transcriptome data of leaves at different developmental stages from , we identified differentially expression genes (DEGs) functioning in leaf development. A candidate gene named () had high similarity in sequence with , and used for further research. We isolated the full-length gene and its promoter from . Subsequently, we analyzed the function of the gene and its promoter activity via transformation into .

Results: In this study, we found that the and are homologous in sequence but not homologous in function. Unlike the role of in leaf serration and SAM formation, the mainly regulates cotyledon development and rosette leaf number. Histochemical -glucuronidase (GUS) staining revealed that was expressed in the cotyledons of seedlings, indicating that the may play a role in cotyledon development. Ectopic expression of resulted in long, narrow cotyledons without petioles, abnormal lamina epidermis cells and defective vascular tissue in cotyledons, and these results were consistent with the expression pattern. Further analysis showed that overexpression of also induced numerous rosette leaves. Also, and other related genes showed a severe response in by introducing exogenous auxin stimulation, partly revealed that affects the leaf development by regulating the auxin content.

Conclusions: These results suggest that may play a critical role in leaf development and morphogenesis in , and our findings provide insight into the molecular mechanisms of leaf development in .