代谢组与转录组联合分析毕节市高海拔烟区烟叶类黄酮代谢差异

Combined metabolomics and transcriptome analysis on differences in flavonoid metabolism in tobacco leaves from high-altitude tobacco growing areas in Bijie City

为明确毕节市高海拔地区烟叶的代谢特征,分别以该地3个烟叶产区(海拔>1800 m)的韭菜坪2号和云烟87烟叶为材料进行代谢组与转录组联合分析,初步鉴定了韭菜坪2号与云烟87烟叶中的差异代谢物和差异基因,并通过加权基因共表达网络分析筛选了关键差异基因的模块。结果表明:3个产区的韭菜坪2号与云烟87烟叶代谢差异明显,其中类黄酮代谢物异鼠李素在韭菜坪2号中高积累;同时共鉴定出265个共有的差异表达基因,主要在类黄酮生物合成途径、黄酮与黄酮醇生物合成途径显著富集;加权基因共表达网络分析共鉴定出9个与异鼠李素相关的基因模块,其中2个模块显著富集到类黄酮生物合成途径、黄酮与黄酮醇生物合成途径;进一步研究分析发现,韭菜坪2号中NtPAL1、NtCHIL、NtF3H、NtTT7和NtFLS1基因下调表达可能抑制了苯丙氨酸、山奈酚及其衍生物、槲皮素及其衍生物的积累水平,而NtASMTs、NtROMTs和NtCCoAMT等甲基转移酶基因的上调表达与烟叶中异鼠李素高积累相关。本研究结果初步表明黄酮类生物合成相关途径对韭菜坪2号在高海拔适应性方面具有一定作用,为深入解析韭菜坪2号的高海拔生长适应性机制提供理论指导。

To investigate the metabolic characteristics of tobacco leaves from high-altitude areas in Bijie City,combined metabolome and transcriptome analysis was performed on the leaves of cv.Jiucaiping No.2 and Yunyan 87 from three tobacco growing areas in Bijie with an altitude above 1800 m.The differential metabolites and genes between Jiucaiping No.2 and Yunyan 87 were identified by comparative analysis,and the key gene modules contributing to the differences were identified by weighted gene co-expression network analysis.The results showed that there were metabolic differences between Jiucaiping No.2 and Yunyan 87 tobacco leaves from the three tobacco growing areas,and the flavonoid metabolite isorhamnetin was highly accumulated in Jiucaiping No.2 leaves.A total of 265 common differentially expressed genes were identified in the leaves,which were mainly enriched in the flavonoid biosynthetic pathway and the flavone and flavonol biosynthetic pathways.Nine gene modules related to isorhamnetin were identified by the weighted gene co-expression network,two of which were significantly enriched in the flavonoid biosynthetic pathway and the flavone and flavonol biosynthetic pathways.Further integrated analysis revealed that the down-regulated expression of NtPAL1,NtCHIL,NtF3H,NtTT7 and NtFLS1 genes in Jiucaiping No.2 leaves might lead to the low accumulation of phenylalanine,kaempferol and its derivatives,quercetin and its derivatives in tobacco leaves,while the up-regulated expression of methyltransferase genes such as NtASMTs,NtROMTs and NtCCoAMT might promote the high accumulation of isorhamnetin in tobacco leaves.This study tentatively demonstrates that the differential changes in flavonoid-related metabolic pathways have a certain impact on the high-altitude adaptation of Jiucaiping No.2,and the results provide theoretical guidance for the in-depth analysis of the growth adaptation mechanism of Jiucaiping No.2 in high-altitude areas.