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<p>Flavonoids are key functional components in the roots of sugar beets (<i>Beta vulgaris</i> var. rubra et lutea), exhibiting significant content differences between red- and yellow-root varieties. However, the transcriptional regulatory mechanisms remain unclear. This study utilized red beet (RG1-T1 seedling stage, RG2-T2 rosette stage, RG3-T3 fleshy root enlargement stage) and yellow beet (YG1-T1, YG2-T2, YG3-T3) roots as experimental materials. Through transcriptomic sequencing (RNA-seq), weighted gene co-expression network analysis (WGCNA), phylogenetic analysis, and real-time quantitative PCR (qRT-PCR) validation, we systematically elucidated the molecular regulatory network governing flavonoid biosynthesis. Results revealed significantly higher flavonoid content in red beets than yellow beets, with both reaching accumulation peaks at the T3 stage (red beet: 12.36 ± 0.89&#xa0;mg RE/g FW; yellow beet: 5.68 ± 0.42&#xa0;mg RE/g FW). Pairwise comparisons between genotypes (RG1vsYG1, RG2vsYG2, RG3vsYG3, and comparisons within each cultivar across developmental stages, 563 differentially expressed genes (DEGs) were identified. Among these, 112 were directly associated with flavonoid synthesis and were significantly enriched in the phenylpropanoid biosynthesis (ko00940) and flavonoid biosynthesis (ko00941) pathways. Through phylogenetic tree and conserved motif analysis of R2R3-MYB proteins, three key MYB transcription factors regulating flavonoid synthesis were identified (BVRB_3g053050, BVRB_8g182310, BVRB_004790) WGCNA analysis identified phenylalanine ammonia-lyase (PAL, BVRB_3g063580) and 4- -coumaric acid-CoA ligase (4CL, BVRB_9g205510) as core hub genes, with significant interaction between the bHLH transcription factor (BVRB_1g002070) and PAL. Collinearity analysis confirmed evolutionary conservation of key genes between varieties. Co-expression analysis revealed a T1→T3 synergistic upregulation trend (1.8–3.2-fold increase) in red beet genes, while yellow beet showed weak synergy (0.5–1.2-fold increase). qRT-PCR validation demonstrated high consistency between key gene expression trends and transcriptomic data (R²=0.844). This study reveals that red sugar beet promotes flavonoid synthesis through the coordinated expression of hub genes and structural genes regulated by the MYB-bHLH complex. It provides molecular targets and theoretical basis for genetic improvement of functional quality in sugar beet, and offers insights into the regulatory mechanisms underlying differential accumulation of plant secondary metabolites.</p>

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Comparison of distinct transcriptional expression patterns of flavonoid biosynthesis in table beets (Beta vulgaris L.) with differently colored roots

  • 期刊论文

  • 发表日期：

    2026年3月16日

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  • Shuo Chen,
  • Naixin Liu,
  • Qin Zhou,
  • Mengpu Jin,
  • Yanan Liu

摘要

Flavonoids are key functional components in the roots of sugar beets (Beta vulgaris var. rubra et lutea), exhibiting significant content differences between red- and yellow-root varieties. However, the transcriptional regulatory mechanisms remain unclear. This study utilized red beet (RG1-T1 seedling stage, RG2-T2 rosette stage, RG3-T3 fleshy root enlargement stage) and yellow beet (YG1-T1, YG2-T2, YG3-T3) roots as experimental materials. Through transcriptomic sequencing (RNA-seq), weighted gene co-expression network analysis (WGCNA), phylogenetic analysis, and real-time quantitative PCR (qRT-PCR) validation, we systematically elucidated the molecular regulatory network governing flavonoid biosynthesis. Results revealed significantly higher flavonoid content in red beets than yellow beets, with both reaching accumulation peaks at the T3 stage (red beet: 12.36 ± 0.89 mg RE/g FW; yellow beet: 5.68 ± 0.42 mg RE/g FW). Pairwise comparisons between genotypes (RG1vsYG1, RG2vsYG2, RG3vsYG3, and comparisons within each cultivar across developmental stages, 563 differentially expressed genes (DEGs) were identified. Among these, 112 were directly associated with flavonoid synthesis and were significantly enriched in the phenylpropanoid biosynthesis (ko00940) and flavonoid biosynthesis (ko00941) pathways. Through phylogenetic tree and conserved motif analysis of R2R3-MYB proteins, three key MYB transcription factors regulating flavonoid synthesis were identified (BVRB_3g053050, BVRB_8g182310, BVRB_004790) WGCNA analysis identified phenylalanine ammonia-lyase (PAL, BVRB_3g063580) and 4- -coumaric acid-CoA ligase (4CL, BVRB_9g205510) as core hub genes, with significant interaction between the bHLH transcription factor (BVRB_1g002070) and PAL. Collinearity analysis confirmed evolutionary conservation of key genes between varieties. Co-expression analysis revealed a T1→T3 synergistic upregulation trend (1.8–3.2-fold increase) in red beet genes, while yellow beet showed weak synergy (0.5–1.2-fold increase). qRT-PCR validation demonstrated high consistency between key gene expression trends and transcriptomic data (R²=0.844). This study reveals that red sugar beet promotes flavonoid synthesis through the coordinated expression of hub genes and structural genes regulated by the MYB-bHLH complex. It provides molecular targets and theoretical basis for genetic improvement of functional quality in sugar beet, and offers insights into the regulatory mechanisms underlying differential accumulation of plant secondary metabolites.