Native Red Mulberry (Morus rubra) is found in riparian habitats in eastern North America stretching from the east coast to the eastern boundary of the Great Plains. Its range extends as far south as Florida and as far north as southern Ontario, Canada. Previous studies reported that M. rubra exhibits a subdioecious breeding system, with over 90% of trees being unisexual. While the flowers of M. rubra are consistently unisexual, some trees can have either unisexual or hermaphrodite catkins. Additionally, the monoecious plants of this species produce either staminate and pistillate catkins or mixed catkins on the same tree. The main objective of this research was to identify and characterize M. rubra genes involved in sex determination. Currently, whole genome sequencing and gene annotation works are in progress. In addition, for the RNA-seq analysis, sampling of tissues from the developing male and female flowers is underway. This poster presentation will showcase the findings of the whole genome sequencing, and identification of MADS-Box genes believed to play important role in sex expression and breeding system of M. rubra.