Expression of the subgroup IIIf bHLH transcription factor CpbHLH1 from Chimonanthus praecox (L.) in transgenic model plants inhibits anthocyanin accumulation

• Published in: Plant cell reports Vol. 39; no. 7; pp. 891 - 907
• Main Authors: Zhao, Rong, Song, Xiaoxi, Yang, Nan, Chen, Longqing, Xiang, Lin, Liu, Xiu-Qun, Zhao, Kaige
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.07.2020; Springer Nature B.V
• Subjects: Accumulation; Amino Acid Sequence; Anthocyanins; Anthocyanins - metabolism; Arabidopsis; Arabidopsis - genetics; Basic Helix-Loop-Helix Transcription Factors - chemistry; Basic Helix-Loop-Helix Transcription Factors - genetics; Basic Helix-Loop-Helix Transcription Factors - metabolism; Biomedical and Life Sciences; Biosynthesis; Biosynthetic Pathways - genetics; Biotechnology; Calycanthaceae - metabolism; Cell Biology; Cell Nucleus - metabolism; Chimonanthus praecox; Complementation; Flavonoids; Fluorescence; Gene expression; Gene Expression Regulation, Plant; Genes; Helix-loop-helix proteins (basic); Life Sciences; Nicotiana - genetics; Organ Specificity; Original Article; Phylogeny; Plant Biochemistry; Plant Sciences; Plant species; Plants, Genetically Modified; Polymerase chain reaction; Protein Binding; Proteins; Repressor Proteins - metabolism; Subcellular Fractions - metabolism; Subgroups; Tobacco; Transcription factors; Transgenic plants; Yeasts; Wintersweet; Anthocyanin accumulation; Negative regulation; Flavonoids pathway; bHLH transcription factor
• ISSN: 0721-7714; 1432-203X
• DOI: 10.1007/s00299-020-02537-9

Key message Overexpression of CpbHLH1 in Arabidopsis and tobacco resulted in a dramatic decrease in anthocyanin accumulation by repressing the expression of late biosynthesis genes in the flavonoid biosynthesis pathway. Many basic helix–loop–helix (bHLH) transcription factors (TFs) of subgroup IIIf have been characterized as anthocyanin-associated activators in higher plants, but information regarding bHLH TFs that inhibit anthocyanin accumulation remains scarce. In this study, the subgroup IIIf bHLH TF CpbHLH1 from Chimonanthus praecox (L.) was identified as a negative regulator of anthocyanin accumulation. Our results showed that overexpression of CpbHLH1 in model plant species, Arabidopsis and tobacco, resulted in a dramatic decrease in anthocyanin content, whereas the content of proanthocyanidin was little affected. Quantitative RT-PCR (qRT-PCR) assays of the structural genes in the flavonoid biosynthesis pathway revealed that CpbHLH1 inhibits anthocyanin accumulation mainly through repressing the expression of late biosynthesis genes (LBGs). Interactions between CpbHLH1 protein and AtPAP1/NtAN2 protein were detected via yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays. This is the first bHLH repressor of anthocyanin biosynthesis identified in dicotyledons. These results can help us better understand the anthocyanin regulatory network in plants and may provide insights into the diverse functions of bHLH proteins.