Data Sheet 1_Integrated physiological and transcriptomic analysis uncovers the mechanism of moderate nitrogen application on promoting the growth and (-)-borneol accumulation of Blumea balsamifera.zip

IntroductionBlumea balsamifera, a half-woody plant belonging to the Asteraceae family, is valued as both a medicinal and industrial crop primarily for its phytochemical component, (-)-borneol. Nitrogen (N) is essential for regulating the growth of B. balsamifera and the biosynthesis of (-)-borneol; however, the molecular mechanisms by which N influences these processes remain inadequately understood. This study aimed to elucidate the effects of N on growth and (-)-borneol synthesis at the molecular level.
MethodsA field experiment was conducted in which B. balsamifera plants were fertilized with three different nitrogen regimes: 0 kg N ha-1 (control, CK), 150 kg N ha-1 (N1 treatment), and 300 kg N ha-1 (N2 treatment). Physiological and biochemical assessments were performed to evaluate the growth and metabolic responses of the plants under these varying N conditions. Additionally, transcriptome sequencing of leaves of B. balsamifera was conducted to elucidate the underlying molecular mechanisms involved.
Results and discussionThe results indicated that both the N1 and N2 treatments significantly promoted the growth of B. balsamifera, with the 150 kg N ha-1 treatment (N1) resulting in the most favorable effects. Under the N1 treatment, the leaves harvested in October, November, and December exhibited the highest accumulation of (-)-borneol, with yields of 782 mg plant-1, 1102 mg plant-1, and 1774 mg plant-1, respectively, which were significantly different from those observed in the CK and N2 treatments. Comparative transcriptome analysis revealed a total of 6,714 differentially expressed genes (DEGs). Notably, several DEGs associated with auxin signaling and N metabolism were upregulated in the N1 and N2 treatments. In contrast, many DEGs related to carbohydrate metabolism, terpenoid backbone biosynthesis, monoterpenoid biosynthesis, and flavonoid biosynthesis were significantly upregulated in the CK treatment. Moreover, potential transcription factors (TFs) that may link N nutrition with the synthesis of medicinal components were identified. Our study demonstrates that N can enhance the accumulation of (-)-borneol in B. balsamifera when applied in appropriate quantities. These findings provide a comprehensive understanding of the relationship between N nutrition and (-)-borneol yield in B. balsamifera, offering valuable insights for future cultivation practices.

1 引言
艾纳香（Blumea balsamifera）是隶属于菊科（Asteraceae）的半木质植物，因其植物化学成分左旋龙脑（(-)-borneol）而被作为药用与工业作物广泛栽培。氮（N）是调控艾纳香生长及左旋龙脑生物合成的关键元素，但氮素影响上述过程的分子机制仍未得到充分阐明。本研究旨在从分子层面解析氮素对艾纳香生长与左旋龙脑合成的调控作用。

2 材料与方法
本研究设置田间试验，对艾纳香植株施加三种施氮水平：0 kg N ha⁻¹（对照组，CK）、150 kg N ha⁻¹（N1处理组）及300 kg N ha⁻¹（N2处理组）。通过生理生化指标测定，评估不同施氮条件下植株的生长与代谢响应。此外，对艾纳香叶片开展转录组测序（transcriptome sequencing），以解析相关潜在分子机制。

3 结果与讨论
结果表明，N1与N2处理均显著促进了艾纳香的生长，其中150 kg N ha⁻¹处理（N1）的促生长效果最优。在N1处理下，10月、11月及12月采收的叶片中左旋龙脑积累量最高，单株产量分别达782 mg、1102 mg及1774 mg，与对照组及N2处理组存在显著差异。比较转录组分析共鉴定出6714个差异表达基因（differentially expressed genes, DEGs）。值得注意的是，与生长素信号通路及氮代谢相关的多个DEGs在N1与N2处理组中显著上调。与之相反，与碳水化合物代谢、萜类骨架生物合成、单萜类生物合成及黄酮类生物合成相关的大量DEGs在对照组中显著上调。本研究还鉴定出可将氮营养与药用成分合成相关联的潜在转录因子（transcription factors, TFs）。本研究证实，适量施用氮肥可提升艾纳香中左旋龙脑的积累量。上述结果全面阐明了艾纳香氮营养与左旋龙脑产量之间的关联，为后续栽培实践提供了重要参考依据。