Decoding the Flower-Anthesis Mechanism in Cestrum nocturnum and Cestrum diurnum

The present study investigates the flower-anthesis mechanism in two closely related plant species, Cestrum diurnum and Cestrum nocturnum. These plants are morphologically similar, but exhibit distinct flowering times: C. diurnum flowers during the day, whereas C. nocturnum blooms at night. This contrast in flowering time makes them ideal subjects for this study. Physiological parameters like photosynthetic rate, floral development, and chlorophyll content were analyzed along with transcriptome sequencing. Transcripts related to blooming time were analyzed using de novo sequencing analysis, with emphasis on photoperiod, autonomous, circadian clock, and vernalization pathways. Gene Ontology and KEGG pathway enrichment analysis revealed differences in morphology and physiology. Transcription factors (bHLH, ERF, MYB, and C2H2) involved in regulating flowering time were identified between these two species. The delayed flowering of C. nocturnum was validated by qRT-PCR, which showed the involvement of FT, FLC, and CO genes. Physical attributes such as larger leaves and higher chlorophyll content were two distinctive characteristics of C. nocturnum attributed to higher PHYA levels. Explaining the different flowering events between these two species, the study implies that C. nocturnum focuses on flower formation, photoperiodic responses, and meristem management, whereas C. diurnum prioritizes growth and development.