Modulation of anthocyanin accumulation in storage roots of sweetpotato by transcription factor IbMYB1-2 through direct binding to anthocyanin biosynthetic gene promoters

Wenqian Hou; Ping Yan; Tianye Shi; Pengzhou Lu; Weiwei Zhao; Huimin Yang; Liqian Zeng; Jun Yang; Zongyun Li; Weijuan Fan; Lei Zhang

doi:10.1016/j.plaphy.2023.02.050

Modulation of anthocyanin accumulation in storage roots of sweetpotato by transcription factor IbMYB1-2 through direct binding to anthocyanin biosynthetic gene promoters

Plant Physiol Biochem. 2023 Mar:196:868-879. doi: 10.1016/j.plaphy.2023.02.050. Epub 2023 Mar 2.

Authors

Wenqian Hou¹, Ping Yan², Tianye Shi³, Pengzhou Lu⁴, Weiwei Zhao⁴, Huimin Yang⁴, Liqian Zeng⁴, Jun Yang⁵, Zongyun Li⁴, Weijuan Fan⁶, Lei Zhang⁷

Affiliations

¹ Jiangsu Key Laboratory of Phylogenomics & Comparative Genomics, School of Life Sciences, Jiangsu Normal University, 101 Shanghai Street, Xuzhou, 221100, Jiangsu Province, People's Republic of China. Electronic address: wenqianh@jsnu.edu.cn.
² Jiangsu Key Laboratory of Phylogenomics & Comparative Genomics, School of Life Sciences, Jiangsu Normal University, 101 Shanghai Street, Xuzhou, 221100, Jiangsu Province, People's Republic of China. Electronic address: 2020221635@jsnu.edu.cn.
³ Jiangsu Key Laboratory of Phylogenomics & Comparative Genomics, School of Life Sciences, Jiangsu Normal University, 101 Shanghai Street, Xuzhou, 221100, Jiangsu Province, People's Republic of China. Electronic address: 2020180490@jsnu.edu.cn.
⁴ Jiangsu Key Laboratory of Phylogenomics & Comparative Genomics, School of Life Sciences, Jiangsu Normal University, 101 Shanghai Street, Xuzhou, 221100, Jiangsu Province, People's Republic of China.
⁵ Shanghai Key Laboratory of Plant Functional Genomics and Resources, Shanghai Chenshan Botanical Garden, Shanghai, 201602, People's Republic of China.
⁶ Shanghai Key Laboratory of Plant Functional Genomics and Resources, Shanghai Chenshan Botanical Garden, Shanghai, 201602, People's Republic of China. Electronic address: wjfan@sibs.ac.cn.
⁷ Jiangsu Key Laboratory of Phylogenomics & Comparative Genomics, School of Life Sciences, Jiangsu Normal University, 101 Shanghai Street, Xuzhou, 221100, Jiangsu Province, People's Republic of China. Electronic address: leizhang@jsnu.edu.cn.

PMID: 36878161
DOI: 10.1016/j.plaphy.2023.02.050

Abstract

The storage roots of purple-fleshed sweetpotato rich in anthocyanins are considered nutrient-rich foods with health effects. However, the molecular mechanism underlying anthocyanin biosynthesis and regulation remains to be revealed. In this study, IbMYB1-2 was isolated from purple-fleshed sweetpotato "Xuzishu8". The phylogenetic and sequence analysis indicated that IbMYB1-2 belongs to the SG6 subfamily with a conserved bHLH motif. Subcellular localization analysis and transcriptional activity assay revealed that IbMYB1-2 is a key transcriptional activator and is specific to the nucleus. Agrobacterium rhizogenes-mediated overexpression of IbMYB1-2 in sweetpotato through in vivo root transgenic system led to an increase in anthocyanins in the root of sweetpotato. qRT-PCR and transcriptome analysis depicted that the transcript levels of IbMYB1-2, IbbHLH42, and eight structural genes that are associated with the synthesis of anthocyanin were upregulated in overexpressed IbMYB1-2 transgenic roots. Dual-luciferase reporter (DLR) assay and yeast one-hybrid (Y1H) assay demonstrated IbMYB1-2 binding to the promoter regions of IbbHLH42 and other anthocyanin biosynthetic genes, including IbCHS, IbCHI, IbF3H, IbDFR, IbANS, IbGSTF12, IbUGT78D2, and IbUF3GT. Moreover, IbbHLH42 was shown to be an active enhancer for the formation of MYB-bHLH-WD40 (MBW) complex, which strongly supports the promoter activities of the IbCHS, IbANS, IbUGT78D2, and IbGSTF12 genes to induce anthocyanin accumulation. Taken together, our findings not only revealed the underlying regulatory molecular mechanism of IbMYB1-2 for anthocyanin accumulation in the storage roots of sweetpotato but also uncovered a potential mechanism by which IbbHLH42 modulated anthocyanin biosynthesis through a positive feedback regulatory loop.

Keywords: Anthocyanin accumulation; MYB transcription Factor; Purple-fleshed sweetpotato; bHLH transcription factor.

MeSH terms

Anthocyanins* / metabolism
Gene Expression Regulation, Plant
Ipomoea batatas* / genetics
Ipomoea batatas* / metabolism
Phylogeny
Plant Proteins / metabolism
Polymerase Chain Reaction
Transcription Factors / metabolism

Substances

Anthocyanins
Transcription Factors
Plant Proteins