Yu Xian-Mei, Wang Jie, Gao Rui, Gong Bang-Chu, Ai Cheng-Xiang
Shandong Institute of Pomology, Tai'an, China.
Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Fuyang, China.
Front Plant Sci. 2022 May 25;13:904208. doi: 10.3389/fpls.2022.904208. eCollection 2022.
Persimmon leaves are used for making persimmon leaf tea or as functional ingredients due to their enrichment in flavonoids, the beneficial mineral contents, and favorable flavors contributed by volatile aroma compounds. The varieties/cultivars had a significant influence on the quality and flavor of persimmon leaf tea. In this study, the integrated metabolomic-transcriptomic analysis was conducted to investigate the potential in flavonoid biosynthesis, mineral absorption, and degradation of aromatic compounds from tender leaves of " Heishi" (HS), " Thunb. Nishimurawase" (NM), and " Thunb. Taifu" (TF), using rootstock " Linn" (DL) as the control. The metabolomic analysis showed that 382, 391, and 368 metabolites were differentially accumulated in the comparison of DL vs. HS, DL vs. NM, and DL vs. TF, respectively, and 229 common metabolites were obtained by comparative analysis. By RNA sequencing, 182,008 unigenes with 652 bp of mean length were annotated and 2,598, 3,503, and 3,333 differentially expressed genes (DEGs) were detected from the comparison of DL vs. HS, DL vs. NM, and DL vs. TF, respectively. After the Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment, 6, 6, and 3 DEGs [with | log2(fold change)| ≥ 1 simultaneously in the three comparisons] involved in flavonoid biosynthesis, mineral absorption, and degradation of aromatic compounds, respectively, were selected for quantitative reverse transcription-polymerase chain reaction (qRT-PCR) validation and the consistent trends of the relative expression level of each DEG with RNA sequencing (RNA-seq) data were observed. Based on the transcriptomic analysis and qRT-PCR validation, it was observed that the leaves of HS, NM, and TF had the greatest level of mineral absorption, flavonoid biosynthesis, and degradation of aromatic compounds, respectively. In addition, a positive correlation between the 15 DEGs and their metabolites was observed by the conjoint analysis. Thus, the tender leaves of HS, NM, and TF could be recommended for the production of persimmon leaf tea rich in mineral elements, flavonoid, and aroma compounds, respectively.
柿叶因富含黄酮类化合物、有益矿物质成分以及挥发性香气化合物所赋予的宜人风味，而被用于制作柿叶茶或作为功能性成分。品种/栽培变种对柿叶茶的品质和风味有显著影响。在本研究中，以砧木“Linn”（DL）作为对照，对“黑柿”（HS）、“西村早生”（NM）和“太富”（TF）嫩叶中的黄酮类生物合成、矿物质吸收以及芳香化合物降解潜力进行了代谢组学-转录组学综合分析。代谢组学分析表明，在DL与HS、DL与NM、DL与TF的比较中，分别有382、391和368种代谢物差异积累，通过比较分析得到229种常见代谢物。通过RNA测序，注释了平均长度为652 bp的182,008个单基因，在DL与HS、DL与NM、DL与TF的比较中，分别检测到2,598、3,503和3,333个差异表达基因（DEG）。经过基因本体论（GO）和京都基因与基因组百科全书（KEGG）富集分析后，分别选择了6、6和3个参与黄酮类生物合成、矿物质吸收以及芳香化合物降解的DEG（在三次比较中同时满足|log2（倍数变化）|≥1）进行定量逆转录-聚合酶链反应（qRT-PCR）验证，并观察到每个DEG的相对表达水平与RNA测序（RNA-seq）数据具有一致趋势。基于转录组学分析和qRT-PCR验证，观察到HS、NM和TF的叶片分别在矿物质吸收、黄酮类生物合成和芳香化合物降解方面具有最高水平。此外，通过联合分析观察到15个DEG与其代谢物之间存在正相关。因此，HS、NM和TF的嫩叶分别可推荐用于生产富含矿物质元素、黄酮类和香气化合物的柿叶茶。
