Hao Da Cheng, Chen Shi Lin, Osbourn Anne, Kontogianni Vassiliki G, Liu Li Wei, Jordán Maria J
Biotechnology Institute, School of Environment, Dalian Jiaotong University, Dalian 116028, China.
Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing 100700, China.
Gene. 2015 Mar 1;558(1):41-53. doi: 10.1016/j.gene.2014.12.043. Epub 2014 Dec 20.
Salvia sclarea is a traditional medicinal and aromatic plant that grows in Europe and produces various economically important compounds, including phenylpropanoid derivatives and terpenoids. Methyl jasmonate (MeJA) is commonly used to elicit plant stress responses. However, how MeJA enhances production of secondary metabolites in S. sclarea is not well understood. We performed a genome-wide analysis of temporal gene expression in S. sclarea leaves and roots. The transcriptome profiles 0, 10 and 26 h after MeJA treatment were analyzed by Illumina RNA-Seq. A total of 16,142 isogenes (average length 866bp; N50 1035bp) were obtained by de novo assembly of 35,757,567 raw sequencing reads. When these sequencing reads were mapped onto the assembled Unigenes, 3236, 2792 and 798 Unigenes were found to be expressed differentially between 0 and 10h, 0 and 26 h, and 10 and 26h, respectively. These included many secondary metabolite biosynthesis, stress and defense-related genes. A qRT-PCR analysis confirmed the expression profiles of selected differentially expressed genes (DEGs) revealed by RNA-Seq data, and also extended our analysis of differential gene expression to 73 h. Our investigations revealed temporal differences in the responses of S. sclarea to MeJA treatment. MeJA treatment induced the expression of a large number of genes involved in phenylpropanoid biosynthesis, especially between 0 and 10h, and 0 and 26 h. Additionally, many genes encoding transcription factors, cytochrome P450s, glycosyltransferases, methyltransferases and transporters were shown to respond to MeJA elicitation. DEGs related to structural molecule activity and cell death showed a significant temporal variation. A chromatographic analysis of metabolites at 26h, 73h and six days after MeJA treatment indicated that these transcriptomic changes precede MeJA-induced changes in secondary metabolite content. This study sheds light on the molecular mechanisms of MeJA elicitation and is helpful in understanding how exogenous MeJA treatment mediates extensive plant transcriptome reprogramming/remodeling. Our results can be utilized to characterize genes related to secondary metabolism and their regulation, and in breeding S. sclarea for desirable chemotypes.
鼠尾草是一种传统的药用和芳香植物，生长于欧洲，能产生多种具有重要经济价值的化合物，包括苯丙素衍生物和萜类化合物。茉莉酸甲酯（MeJA）常用于引发植物的应激反应。然而，MeJA如何提高鼠尾草中次生代谢产物的产量尚不清楚。我们对鼠尾草叶片和根部的基因表达进行了全基因组时间分析。通过Illumina RNA-Seq分析了MeJA处理后0、10和26小时的转录组图谱。通过对35,757,567条原始测序读数进行从头组装，共获得了16,142个同基因（平均长度866bp；N50 1035bp）。当将这些测序读数映射到组装好的单基因上时，分别在0和10小时、0和26小时以及10和26小时之间发现了3236、2792和798个差异表达的单基因。其中包括许多次生代谢产物生物合成、应激和防御相关基因。qRT-PCR分析证实了RNA-Seq数据揭示的选定差异表达基因（DEG）的表达谱，并将我们对差异基因表达的分析扩展到了73小时。我们的研究揭示了鼠尾草对MeJA处理反应的时间差异。MeJA处理诱导了大量参与苯丙素生物合成的基因表达，尤其是在0和10小时以及0和26小时之间。此外，许多编码转录因子、细胞色素P450、糖基转移酶、甲基转移酶和转运蛋白的基因显示出对MeJA诱导的反应。与结构分子活性和细胞死亡相关的DEG表现出显著的时间变化。对MeJA处理后26小时、73小时和六天的代谢产物进行色谱分析表明，这些转录组变化先于MeJA诱导的次生代谢产物含量变化。本研究揭示了MeJA诱导的分子机制，有助于理解外源MeJA处理如何介导广泛的植物转录组重编程/重塑。我们的结果可用于鉴定与次生代谢及其调控相关的基因，并用于培育具有理想化学型的鼠尾草。
