Genome-wide identification and expression analysis of the LdGRAS gene family

Low-temperature exposure is critical for dormancy release and subsequent growth and flowering in Lilium species. Using the Lanzhou lily (L. davidii var. unicolor (Hoog) Cotton) as a model, a genome-wide analysis was conducted to identify and characterize members of the GRAS gene family and to screen potential candidate genes involved in bulb dormancy release. A total of 52 LdGRAS genes were identified and classified into nine evolutionary subgroups exhibiting conserved structural features and motif compositions. Comparative synteny analysis revealed 29 and 38 collinear gene pairs between the LdGRAS family and the genomes of Elaeis guineensis Jacq. and Phoenix dactylifera L., respectively. Promoter analysis indicated that LdGRAS genes harbored numerous cis-regulatory elements associated with light responsiveness, growth and development regulation, and stress adaptation, while only LdGRAS25 contained elements associated with cell cycle regulation. Transcriptomic analysis revealed that LdGRAS genes exhibited tissue-specific expression patterns, with the highest expression levels observed in roots and ovaries. RT-qPCR analysis further demonstrated that LdGRAS25 expression in bulb apical meristems under cold treatment was significantly elevated compared with that under normal temperature conditions. Collectively, these findings indicate that the LdGRAS gene family exhibits tissue-specific expression in Lanzhou lily and participates in stress responses. Notably, LdGRAS25 was identified as a low-temperature-induced gene upregulated during dormancy release, representing a promising candidate for elucidating the molecular mechanisms underlying temperature-mediated dormancy regulation in lilies.