Integrated analyses of transcriptome, metabolome and floral B-class genes reveal sexual dimorphism in Eucommia...

Eucommia ulmoides is a dioecious plant species that has been widely utilized as an important traditional Chinese medicine. To investigate sexual dimorphism and its underling molecular basis in E. ulmoides, we conducted an integrated analysis of transcriptomic and metabolomic data, alongside functional gene studies, for the first time. The results revealed that 8,811 (43.72%) of genes expressed in flowers were sex-biased genes, significantly more than the 116 (0.078%) identified in leaves. Among these, two male-biased and four female-biased genes consistently expressed in both flowers and leaves were identified, including two B-class floral organ identity genes, i.e. AP3-like EuMADS39 and PI-like EuMADS28. Additionally, 123 differentially abundant metabolites were detected between male and female flowers. Functional analyses demonstrated that protein EuMADS39 and EuMADS28 are both localized in the nucleus and capable of forming a protein complex. Transgenic Arabidopsis plants co-expressing EuMADS39 and EuMADS28 exhibited an increased number of stamens (7) compared to wild-type plants (6), confirming their roles as B-class genes in the development of unisexual flowers in E. ulmoides. In summary, this study uncovered the sexual dimorphisms in gene expression and metabolite profiles of E. ulmoides, and validated the role of B-class genes in sexual dimorphism of E. ulmoides. Clinical trial number Not applicable.