Table_1_Transcriptome and metabolome analyses reveal molecular mechanisms of anthocyanin-related leaf color variation in poplar (Populus deltoides) cultivars.docx

IntroductionColored-leaf plants are increasingly popular for their aesthetic, ecological, and social value, which are important materials for research on the regulation of plant pigments. However, anthocyanin components and the molecular mechanisms of anthocyanin biosynthesis in colored-leaf poplar remain unclear. Consequently, an integrative analysis of transcriptome and metabolome is performed to identify the key metabolic pathways and key genes, which could contribute to the molecular mechanism of anthocyanin biosynthesis in the colored-leaf cultivars poplar.
MethodsIn this study, integrated metabolite and transcriptome analysis was performed to explore the anthocyanin composition and the specific regulatory network of anthocyanin biosynthesis in the purple leaves of the cultivars ‘Quanhong’ (QHP) and ‘Zhongshanyuan’ (ZSY). Correlation analysis between RNA-seq data and metabolite profiles were also performed to explore the candidate genes associated with anthocyanin biosynthesis. R2R3-MYB and bHLH TFs with differential expression levels were used to perform a correlation analysis with differentially accumulated anthocyanins.
Results and discussionA total of 39 anthocyanin compounds were detected by LC-MS/MS analysis. Twelve cyanidins, seven pelargonidins, five delphinidins, and five procyanidins were identified as the major anthocyanin compounds, which were differentially accumulated in purple leaves of QHP and ZSY. The major genes associated with anthocyanin biosynthesis, including structural genes and transcription factors, were differentially expressed in purple leaves of QHP and ZSY through RNA-sequencing (RNA-seq) data analysis, which was consistent with quantitative real-time PCR analysis results. Correlation analysis between RNA-seq data and metabolite profiles showed that the expression patterns of certain differentially expressed genes in the anthocyanin biosynthesis pathway were strongly correlated with the differential accumulation of anthocyanins. One R2R3-MYB subfamily member in the SG5 subgroup, Podel.04G021100, showed a similar expression pattern to some structural genes. This gene was strongly correlated with 16 anthocyanin compounds, indicating that Podel.04G021100 might be involved in the regulation of anthocyanin biosynthesis. These results contribute to a systematic and comprehensive understanding of anthocyanin accumulation and to the molecular mechanisms of anthocyanin biosynthesis in QHP and ZSY.

引言 彩叶植物因其观赏、生态与社会价值愈发受到青睐，同时也是研究植物色素调控机制的重要实验材料。然而，彩叶杨的花青素组分及其生物合成的分子调控机制仍有待阐明。为此，本研究通过转录组（transcriptome）与代谢组（metabolome）联合分析，筛选关键代谢通路与核心基因，以期揭示彩叶杨栽培品种花青素生物合成的分子调控机制。
方法 本研究以‘全红’（Quanhong, QHP）与‘中源杨’（Zhongshanyuan, ZSY）两个栽培品种的紫叶为材料，通过代谢物与转录组联合分析，解析花青素组分及花青素生物合成的特异性调控网络。同时，通过RNA测序（RNA-seq）数据与代谢物谱的关联分析，筛选与花青素生物合成相关的候选基因。选取表达量存在差异的R2R3-MYB与碱性螺旋-环-螺旋（basic helix-loop-helix, bHLH）转录因子，与差异积累的花青素进行关联分析。
结果与讨论 本研究通过液相色谱-串联质谱（LC-MS/MS）分析，共检测到39种花青素类化合物。其中12种花青素、7种天竺葵素、5种飞燕草素及5种原花青素为主要花青素组分，且在QHP与ZSY的紫叶中积累量存在显著差异。通过RNA-seq数据分析发现，QHP与ZSY紫叶中与花青素生物合成相关的核心基因（包括结构基因与转录因子）表达量存在显著差异，该结果与实时荧光定量PCR（qRT-PCR）验证结果一致。RNA-seq数据与代谢物谱的关联分析显示，花青素生物合成通路中部分差异表达基因的表达模式与花青素的差异积累呈显著相关。SG5亚家族的R2R3-MYB亚家族成员Podel.04G021100的表达模式与部分结构基因高度相似，该基因与16种花青素化合物呈显著相关，提示Podel.04G021100可能参与花青素生物合成的调控。本研究结果为系统解析QHP与ZSY的花青素积累模式及其生物合成的分子机制提供了重要依据。