代谢组与转录组联合解析赤皮青冈叶片黄化变异机制

Combined metabolome and transcriptome analyses reveal the mechanism of etiolated mutant leaves of Quercus gilva

关键词:  赤皮青冈, 叶色突变体, 黄化, 代谢组, 转录组

Key words:  Quercus gilva, leaf-color mutant, etiolation, metabolome, transcriptome

摘要:

为揭示赤皮青冈叶色黄化变异机制,该研究以赤皮青冈叶色变异植株和正常植株的叶片为试验材料,采用超高效液相色谱串联质谱法和高通量RNA测序技术分别进行代谢组和转录组分析。结果表明:(1)代谢组在正离子(POS)、负离子(NEG)模式下分别检测出正常植株和突变体之间存在257个和357个显著差异代谢物(SCMs),其中槲皮素、白矢车菊素、杨梅素等多种黄酮类化合物及其糖苷衍生物(吡喃酮啡肽A、异鼠李素3-葡糖苷酸等)在突变体中显著上调,而叶绿素a、叶绿素b、类胡萝卜素等色素含量则显著下降。(2)转录组测序检测出4 146个差异表达基因(DEGs),其中1 711个基因上调表达,2 435个基因下调表达。(3)KEGG富集分析表明,SCMs和DEGs显著富集到光合作用、卟啉与叶绿素代谢、类黄酮生物合成等途径。综上表明,突变体叶色黄化可能是受到叶绿素合成受阻、叶绿体发育异常及黄酮物质合成增加等因素的综合影响。此外,MYB和bHLH家族基因在突变体中显著上调,证实该两类转录因子参与调控类黄酮生物合成。该研究结果为植物黄化突变的分子机制研究提供了新的见解,也为叶色功能基因挖掘与园林植物育种工作提供了参考。

Abstract:

In order to reveal the etiolation mechanism of gold-coloured mutant leaves of Quercus gilva, a naturally-occurring leaf-color mutant was used as experimental materials, and the metabolome and transcriptome of mutant leaves and normal green leaves were analyzed by ultra-high performance liquid chromatography-Q(UHPLC-Q)Exactive HF-X and high-throughput RNA sequencing, respectively. The results were as follows:(1)A total of 257 and 357 significantly changed metabolites(SCMs)were respectively identified under the positive ion(POS)mode and the negative ion(NEG)mode. Compared with green leaves, the content of some flavonoids such as quercetin, leucocyanidin, myricetin and their glucoside derivatives(pyranodelphinin A, isorhamnetin 3-glucuronide, etc. )increased significantly in mutant leaves, but the content of chlorophyll a, chlorophyll b, and carotenoids decreased significantly.( 2 )A total of 4 146 differentially expressed genes(DEGs)were detected, of which 1 711 were up-regulated and 2 435 were down-regulated.( 3 )KEGG enrichment analysis showed that SCMs and DEGs were mainly enriched in photosynthesis, porphyrin and chlorophyll metabolism, and flavonoid biosynthesis. In conclusion, the inhibition of chlorophyll synthesis, chloroplast developmental abnormalities and promotion of flavonoid synthesis were the main factors driving the leaf etiolation in the mutant Q. gilva. In addition, the genes of the MYB and bHLH families were significantly up-regulated in mutant leaves, confirming these two types of transcription factors were involved in regulating flavonoid biosynthesis. This study provides new molecular insights for the phenomenon of leaf etiolation, and also provides the reference for exploring leaf color-related functional genes and breeding of landscape plant.