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.茅苍术（Atractylodes lancea）根茎富含挥发油，其中含有大量挥发性有机化合物（VOCs），尤以倍半萜类化合物居多。茅苍术挥发油具有极高的药用与经济价值。本研究探究了光质改变对茅苍术挥发性有机化合物生成与组成的影响。我们对茅苍术组培苗施加不同比例的红光、蓝光以及红蓝混合光处理（红光:蓝光=3:1、6:1、9:1），并通过气相色谱-质谱联用（GC-MS）技术对其挥发性有机化合物进行分析。结果表明，光质主要影响茅苍术挥发性有机化合物的生成量，而非其组成成分。我们在根茎中共鉴定出27种挥发性有机化合物，其中13种为倍半萜类物质。随着红光占比提升，倍半萜类化合物的浓度随之升高。我们开展了转录组分析，鉴定得到白光对照组与其余处理组间的差异表达基因（DEGs）。这些差异表达基因显著富集于以下通路：植物-病原体互作、胞吞作用、植物激素信号转导、光合天线蛋白、光合作用以及昼夜节律通路。我们分析了差异表达基因的相对表达量与茅苍术根茎中关键药用成分苍术酮的浓度之间的皮尔逊相关系数，并通过实时定量聚合酶链反应（RT-qPCR）验证了基因表达水平。结果显示，富集通路中的WRKY2、MYC2、热激蛋白（Heat Shock Proteins, HSPs）、EBF1、SAUR72、PYL4以及MKK5基因与苍术酮的积累呈正相关。