Transcriptomic Profiling Across Developmental Stages of Camellia petelotii (Merr.) Sealy Flower

Background: The Camellia genus is widely recognized for its remarkable diversity in floral morphology and coloration, with Camellia petelotii (Merr.) Sealy being particularly notable for its rare golden-yellow flowers, which possess exceptional ornamental value. Despite its horticultural significance, the molecular mechanisms governing its flowering process remain poorly elucidated, presenting a substantial barrier to effective conservation and breeding initiatives. Methods: To address this knowledge gap, we conducted a comprehensive transcriptomic analysis, focusing on three distinct developmental stages of C. petelotii floral organs: the alabastrum stage (S1), the half-opened flower stage (S2), and the full bloom stage (S3). These samples were subjected to high-throughput sequencing using the Illumina platform. Following rigorous quality control and alignment with the reference genome, we performed transcript assembly and integrated comprehensive gene annotation data with quantitative gene expression profiles. Results: Our analysis identified 18,732 differentially expressed genes (DEGs) showing significant expression changes across developmental stages. Notably, we identified 134 DEGs as potential flowering-related genes, which were functionally associated with key pathways involved in floral regulation, including plant hormone signal transduction (e.g., AUX/IAA, ARF, SAUR, GH3, JAR4, GID1 and SOC1), starch (SS, SUS, BAM) and sucrose metabolism (HK, FrK, and GH32), circadian rhythm regulation (e.g., PIF3, ELF3, LHY, and PRR), and the Autonomous pathway. Building upon these findings, we have proposed a comprehensive model illustrating the regulatory network underlying flowering transition in C. petelotii. The reliability of the transcriptomic data was demonstrated through the validation of 11 genes using quantitative real-time PCR (qRT-PCR). Conclusions: These insights not only enhance our understanding of the molecular basis of flowering in this species but also provide a valuable theoretical framework for future genetic improvement and breeding programs of C. petelotii.