摘要：

类黄酮作为大白菜的生物活性物质,具有抗氧化、抗衰老、预防癌症等作用。为探究不同倍体大白菜材料类黄酮积累差异的分子机制,以25份二倍体和25份四倍体大白菜高代纯合自交系为材料,系统比较其总类黄酮含量并筛选极端材料,进而对高、低含量材料进行转录组(RNA-Seq)测序分析。通过 KEGG 富集通路分析鉴定类黄酮化合物生物合成的相关基因,采用RT-qPCR验证差异基因表达模式并构建转录因子调控网络。结果表明,四倍体材料总类黄酮平均含量(10.96 mg/g)略高于二倍体(10.36 mg/g)。RNA-Seq分析表明,二倍体材料比较组之间有11 610个差异基因,四倍体材料比较组之间有6 659个差异基因,其中共有差异基因3 598个。KEGG富集分析在类黄酮和苯丙烷类生物合成通路中鉴定出34个候选基因,筛选出6个关键基因(PAL1、4CL3、CHS3、CHI、CHI3、FLS1)并在高类黄酮含量的二、四倍体材料中上调,其中CHI3在四倍体高类黄酮材料中的表达量显著高于二倍体材料。此外,鉴定出27个bHLH和19个MYB转录因子,调控网络分析显示,MYB网络较bHLH更复杂并占主导地位。通过荧光定量PCR(RT-qPCR)分析显示,所选定6个极端差异基因的表达模式与RNA-Seq中表达趋势一致。筛选出了类黄酮合成途径中的关键结构基因及主要转录因子,发现CHI3对四倍体大白菜材料类黄酮积累有重要作用,为高类黄酮大白菜育种工作提供了候选基因和理论基础。

关键词: 大白菜, 总类黄酮, 转录组, KEGG富集分析, 转录因子

Abstract:

Flavonoids,as bioactive compounds in Chinese cabbage,possess antioxidant,anti-aging,and cancer-preventive properties.To investigate the molecular mechanisms underlying the differences in flavonoid accumulation among different ploidy Chinese cabbage materials,this study utilized 25 diploid and 25 tetraploid high-generation homozygous inbred lines.The total flavonoid content was systematically compared,and extreme lines were selected for transcriptome(RNA-Seq)analysis.Through KEGG pathway enrichment analysis,genes involved in flavonoid biosynthesis were identified,and RT-qPCR was employed to validate the expression patterns of differentially expressed genes and construct a transcription factor regulatory network.The results showed that the average total flavonoid content in tetraploid materials(10.96 mg/g)was slightly higher than that in diploid materials(10.36 mg/g).RNA-Seq analysis revealed 11 610 differentially expressed genes(DEGs)in diploid comparison groups and 6 659 DEGs in tetraploid comparison groups,with 3 598 common DEGs shared between them.KEGG enrichment analysis identified 34 candidate genes in the flavonoid and phenylpropanoid biosynthesis pathways.Six key genes(PAL1,4CL3,CHS3,CHI,CHI3,FLS1)were screened and found to be upregulated in high-flavonoid diploid and tetraploid materials.Among them,CHI3 expression was significantly higher in high-flavonoid tetraploid materials than in diploid materials.Additionally,27 bHLH and 19 MYB transcription factors were identified,and regulatory network analysis indicated that the MYB network was more complex and dominant than the bHLH network.RT-qPCR analysis confirmed that the expression patterns of the six selected key DEGs were consistent with the RNA-Seq data.This study identifies key structural genes and major transcription factors in the flavonoid biosynthesis pathway,revealing the important role of CHI3 in promoting flavonoid accumulation in tetraploid Chinese cabbage,thereby providing candidate genes and a theoretical foundation for breeding high-flavonoid Chinese cabbage.

Key words: Brassica rapa L.ssp. pekinensis, Total flavonoids, Transcriptome, KEGG enrichment analysis, Transcription factors

中图分类号: 

• S634.1

• Q943.2植物基因工程