Transcriptomic insights into the effects of different light quality treatments on the volatile organic compounds in Atractylodes lancea

Atractylodes lancea rhizomes (ARs) are rich in essential oil, which contains a high amount of volatile organic compounds (VOCs), especially sesquiterpenes. The essential oil of A. lancea has high medicinal and economic value. In this study, we investigated the impact of alteration in light quality on the production and composition of VOCs in A. lancea. We applied red light, blue light, and mixed red and blue light of different ratios (red : blue = 3:1, 6:1, and 9:1) treatment on A. lancea plantlets and analyzed their VOCs by gas chromatography-mass spectrometry (GC-MS). Our results showed that light quality mainly affected the production rather than the composition of VOCs in A. lancea. We identified a total of 27 VOCs in the rhizome, 13 of them were sesquiterpenes. The concentration of sesquiterpenes increased as the proportion of red light increased. We performed transcriptomic analysis and identified differentially expressed genes (DEGs) between the white light group (the control group) and the other groups. These DEGs were enriched in the following pathways: plant-pathogen interaction, endocytosis, plant hormone signal transduction, photosynthesis-antenna proteins, photosynthesis, and circadian rhythm. We analyzed the Pearson correlation between the relative expression of the DEGs and the concentration of the key medicinal component in ARs, atractylon, and verified gene expression by RT-qPCR. The results indicated that the genes WRKY2, and MYC2, HSPs, EBF1, SAUR72, PYL4, and MKK5 of the enriched pathways were positively associated with atractylon accumulation.