Physiological, Transcriptomic and Metabolomic Response of Basil (O. basilicum Linn. var. pilosum (Willd.) Benth.) to Red and Blue Light

Basil (Ocimum basilicum Linn. var. pilosum (Willd.) Benth.) is an aromatic plant with high nutritional and economic value, and the synthesis and regulation of its active ingredients have been studied in prior research. However, the mechanisms by which red and blue light—the most effective absorption spectra for photosynthesis—regulate the growth and metabolism of basil remain elusive. This study investigated the changes in phenotype, transcriptome, and metabolome in basil under red and blue light. The photosynthetic efficiency and biomass of basil under blue light (B) treatment were higher than those under white light (W), while red light (R) decreased photosynthesis and biomass. Metabolomic analysis showed that 491 significantly differentially accumulated metabolites were identified between the W and B groups, while 630 differentially accumulated metabolites were identified between the W and R groups. The DAMs were mainly enriched in pathways such as biosynthesis of secondary metabolites, monoterpenoid biosynthesis, limonene and pinene degradation, etc. In addition, transcriptomic analysis revealed that 34,760 and 29,802 differentially expressed genes were detected in the W vs. B pair and the W vs. R pair, respectively, while differentially expressed genes were divided into different unique subclasses, suggesting that they respond to light quality in specific ways. Overall, this work will not only enrich knowledge of the molecular mechanisms of light spectra’s regulation of plant metabolism, but also provide a theoretical basis and guidance for the molecular improvement and quality cultivation of basil.