Decodes the Genetic Architecture of Jade Vine’s Rare Turquoise Blooms

Flowers represent one of the most remarkable evolutionary innovations in angiosperms. Among the vast diversity of floral colors, turquoise stands out as one of the rarest hues in nature. The diversification of floral pigmentation not only mediates the co-evolutionary interactions between plants and their pollinators but also plays a key role in shaping terrestrial biodiversity.

The jade vine (Strongylodon macrobotrys A. Gray), is a leguminous woody climber native to tropical rainforests. It is renowned for its spectacular turquoise racemes, with individual florets resembling birds in flight (Figures 1-2). Cultivated at the South China Botanical Garden (SCBG) for nearly two decades, the species has become an iconic ornamental plant in the garden. However, the molecular basis underlying its unique turquoise coloration has long remained elusive.

Figure 1.Cover of Journal of Integrative Plant Biology (JIPB) featuring our study on the genome of Strongylodon macrobotrys.（Image by YAN et al.）

Recently, a research team from SCBG published a cover article in Journal of Integrative Plant Biology (JIPB) entitled “Haplotype-resolved telomere-to-telomere genome of the jade vine (Strongylodon macrobotrys) provides novel insights into the turquoise flower coloration”(Figure 1). The team successfully assembled a high-quality, haplotype-resolved, telomere-to-telomere (T2T) genome of jade vine. By integrating transcriptomic and metabolomic datasets, they systematically elucidated the formation of this rare floral coloration from genomic, metabolic, and transcriptional regulatory perspectives.

The study revealed that the turquoise phenotype is not generated by a single pigment but instead from synergistic co-pigmentation between the anthocyanin Malvin (malvidin-3,5-O-diglucoside) and the flavonoid co-pigment Saponarin (isovitexin-7-O-glucoside) (Figures 2F–J). Malvin belongs to the delphinidin branch of the anthocyanin biosynthetic pathway, which typically produces blue to violet pigmentation. Saponarin, which appears pale yellow or nearly colorless, enhances the visual intensity of Malvin through intermolecular interactions, thereby shifting the perceived color toward turquoise.

Temporal metabolite profiling further showed dynamic changes during flower development. While Malvin levels decrease as the flowers mature and senesce, Saponarin continues to accumulate (Figures 2F–I). This balance between these two pigments is therefore critical for maintaining the iconic turquoise coloration throughout the flowering period.

Through population demographic reconstruction and multi-omics evolutionary analyses, the researchers also identified population expansion events associated with historical environmental shifts, together with a burst of long terminal repeat (LTR) retrotransposon activity. These genomic dynamics may have contributed to the restructuring of floral color regulatory networks and potentially enhanced the adaptive capacity of jade vine under fluctuating environmental fluctuations (Figures 2E and K).

Overall, this research provides the first comprehensive insight into the genetic and metabolic foundations of turquoise pigmentation in nature, offering a new perspective on floral color innovation and the dynamic evolution of plant genomes.

Figure 2. Morphological characteristics of the turquoise inflorescence of jade vine and its genomic and metabolic basis. The figure illustrates floral morphology at different flowering stages, phylogenetic relationships, population demographic history, and the metabolic and regulatory networks underlying the turquoise flower coloration.（Image by YAN et al.）

Assistant Professor LIU Tongjian, Associate Professor WANG Xinfeng, and Postdoctoral Fellow SHI Dingding from SCBG are the co-first authors of this study. Senior Engineer NING Zulin, Professor ZENG Shaohua, and Professor YAN Haifei serve as the co-corresponding authors. Professor GE Xuejun, Associate Professor HUANG HuirRun, and Dr. WANG Zhiqiang also contributed to the research. Professor HOU Xingliang and Associate Professor TAN Haibo provided valuable guidance and support. Article link: http://dx.doi.org/10.1111/jipb.70136