Jiangsu Key Laboratory for the Research and Utilization of Plant Resources, Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, No. 1 Qianhuhoucun Village, Zhongshan Gate, Nanjing, 210014, China.
The Jiangsu Provincial Platform for Conservation and Utilization of Agricultural Germplasm, Nanjing, China.
Plant Cell Rep. 2021 Sep;40(9):1709-1722. doi: 10.1007/s00299-021-02733-1. Epub 2021 Jun 15.
Transcriptome analysis revealed the potential mechanism of nitrogen regulating steviol glycosides synthesis via shifting of leaf carbon metabolic flux or inducing certain transcription factors. Nitrogen (N) plays key regulatory roles in both stevia (Stevia rebaudiana) growth and the synthesis of its functional metabolite steviol glycosides (SGs), but the mechanism by which this nutrient regulates SGs synthesis remains to be elucidated. To address this question, a pot experiment was performed in a greenhouse where stevia plants fertilized with N (the control as CK plants) and compared with plants without the supply of N. Physiological and biochemical analyses were conducted to test the growth and metabolic responses of plants to N regimes. Our results showed that N deficiency significantly inhibited plant growth and leaf photosynthesis, while increased leaf SGs contents in stevia (49.97, 46.64 and 84.80% respectively for rebaudioside A, stevioside, and rebaudioside C), which may be partly due to "concentration effect". Then, transcriptome analysis was conducted to understand the underlying mechanisms. A total of 535 differentially expressed genes were identified, and carbon metabolism-related events were highlighted by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes. Many of these genes were significantly upregulated by N-deficiency, including those involved in "phenylpropanoid biosynthesis", "flavonoid biosynthesis" and "starch and sucrose metabolism". Our study also analyzed the expression patterns of SGs synthesis-related genes under two N regimes and the potential transcription factors linking N nutrition and SG metabolism. N-deficiency may promote SGs synthesis by changing the carbon metabolism flux or inducing certain transcription factors. Our results provide deeper insight into the relationship between N nutrition and SGs synthesis in stevia plants.
转录组分析揭示了氮通过转移叶片碳代谢通量或诱导某些转录因子来调节甜菊糖苷合成的潜在机制。氮（N）在甜菊（Stevia rebaudiana）的生长和其功能代谢物甜菊糖苷（SGs）的合成中都起着关键的调节作用，但这种营养物质如何调节 SGs 合成的机制仍有待阐明。为了解决这个问题，在温室中进行了盆栽实验，其中甜菊植物用 N 施肥（对照 CK 植物）并与不供应 N 的植物进行比较。进行了生理生化分析以测试植物对 N 处理的生长和代谢反应。我们的结果表明，N 缺乏显著抑制了植物的生长和叶片光合作用，而甜菊叶片 SGs 含量增加（甜菊糖苷 A、甜菊苷和瑞鲍迪苷 C 分别增加 49.97%、46.64%和 84.80%），这可能部分是由于“浓度效应”。然后，进行了转录组分析以了解潜在的机制。总共鉴定了 535 个差异表达基因，通过基因本体论和京都基因与基因组百科全书强调了碳代谢相关事件。许多这些基因受到 N 缺乏的显著上调，包括参与“苯丙烷生物合成”、“类黄酮生物合成”和“淀粉和蔗糖代谢”的基因。我们的研究还分析了两种 N 处理下 SGs 合成相关基因的表达模式以及连接 N 营养和 SG 代谢的潜在转录因子。N 缺乏可能通过改变碳代谢通量或诱导某些转录因子来促进 SGs 的合成。我们的结果为深入了解 N 营养与甜菊植物中 SGs 合成之间的关系提供了依据。
