Functional characterization in Chimonobambusa utilis reveals the role of bHLH gene family in bamboo sheath color variation

Long Tong ¹ Qingping Zeng ² Yuan Guo ³ Yanjie Li ⁴ Hongyan Li ² Lijie Chen ² Xia Liu ^3*

• ¹ Chongqing Academy of Forestry, Chongqing, China, Chongqing, China
• ² International Centre for Bamboo and Rattan, Chinese Academy of Forestry, Beijing, China, Beijing, China
• ³ College of Smart Agriculture, Chongqing University of Arts and Sciences, Chongqing, China, Chongqing, China
• ⁴ Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Zhejiang, China, Zhejiang, China

The basic helix-loop-helix (bHLH) proteins are a large family of transcription factors that are essential to physiology, metabolism, and development. However, the available information is limited about the bHLH gene family in Chimonobambusa utilis, which is widely cultivated in China because of its highquality and economic value. C. utilis cultivars exhibit five natural color variations in their shoot sheaths, but the molecular mechanism behind this color diversity remains unclear. In this study de novo assembly was employed to obtain gene sequences. The transcriptomic analysis of C. utilis yielded a total of 195,977 transcripts and 75,137 unigenes after removing redundancy. To identify pathways related to color formation, GO enrichment analysis was performed on the 44,255 functionally annotated unigenes. The enrichment results revealed that four pathways were most strongly associated with color formation. Phylogenetic, conserved motif, and protein-protein interaction analyses, along with qRT-PCR validation, confirmed CubHLH17's role in red sheath color. This research not only deepens insights into the functional roles of CubHLH genes but also lays the foundation for genetic improvement of bamboo species. We believe these findings will contribute to both scientific research and commercial bamboo cultivation through gene editing technology in the future.