Genome-Wide Identification and Expression Profiling of the GRAS Gene Family in Taxus cuspidate

The GRAS transcription factor family plays pivotal regulatory roles in plant growth and development, hormone signaling, and responses to environmental stresses. Taxus cuspidata, an endangered and nationally protected conifer species endemic to China, is recognized as the sole natural source of paclitaxel-an anti-cancer compound of considerable pharmaceutical importance. While GRAS family genes have been systematically characterized in various plant species, a comprehensive investigation in T. cuspidata has yet to be conducted.

In this study, 26 TcGRAS genes were identified and characterized through genome-wide analysis.

Phylogenetic analysis grouped these genes into seven subfamilies, indicating a high degree of evolutionary conservation. Gene structure analysis revealed that most TcGRAS genes lacked introns, while promoter regions were enriched with cis-acting elements related to light responsiveness, hormone signaling (e.g., MeJA, ABA, SA), and abiotic stress responses. Tissue-specific expression profiling and qRT-PCR analyses showed that several TcGRAS genes were highly expressed in paclitaxel-accumulating organs such as roots, stems, and bark-particularly TcGRAS6, TcGRAS13, and TcGRAS24-suggesting their putative involvement in paclitaxel biosynthesis through hormone-mediated regulatory pathways. Co-expression network analysis further identified TcGRAS13 and TcGRAS14 as central nodes within the transcriptional regulatory network.

This study provides the first genome-wide identification and comprehensive characterization of the GRAS gene family in T. cuspidata, thereby establishing a theoretical framework and providing valuable candidate gene resources for elucidating their biological functions and regulatory roles in secondary metabolism, particularly in paclitaxel biosynthesis.