<i>Tropaeolum majus</i> R2R3 MYB Transcription Factor TmPAP2 Functions as a Positive Regulator of Anthocyanin Biosynthesis

Anthocyanins are an important group of water-soluble and non-toxic natural pigments with antioxidant and anti-inflammatory properties that can be found in flowers, vegetables, and fruits. Anthocyanin biosynthesis is regulated by several different types of transcription factors, including the WD40-re...

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Main Authors: Xiaoping Wang, Wei Wang, Siyu Chen, Yuji Lian, Shucai Wang
Format: Article
Language:English
Published: MDPI AG 2022-10-01
Series:International Journal of Molecular Sciences
Subjects:
Online Access:https://www.mdpi.com/1422-0067/23/20/12395
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author Xiaoping Wang
Wei Wang
Siyu Chen
Yuji Lian
Shucai Wang
author_facet Xiaoping Wang
Wei Wang
Siyu Chen
Yuji Lian
Shucai Wang
author_sort Xiaoping Wang
collection DOAJ
description Anthocyanins are an important group of water-soluble and non-toxic natural pigments with antioxidant and anti-inflammatory properties that can be found in flowers, vegetables, and fruits. Anthocyanin biosynthesis is regulated by several different types of transcription factors, including the WD40-repeat protein Transparent Testa Glabra 1 (TTG1), the bHLH transcription factor Transparent Testa 8 (TT8), Glabra3 (GL3), Enhancer of GL3 (EGL3), and the R2R3 MYB transcription factor Production of Anthocyanin Pigment 1 (PAP1), PAP2, MYB113, and MYB114, which are able to form MYB-bHLH-WD40 (MBW) complexes to regulate the expression of late biosynthesis genes (LBGs) in the anthocyanin biosynthesis pathway. Nasturtium (<i>Tropaeolum majus</i>) is an edible flower plant that offers many health benefits, as it contains numerous medicinally important ingredients, including anthocyanins. By a comparative examination of the possible anthocyanin biosynthesis regulator genes in nasturtium varieties with different anthocyanin contents, we found that <i>TmPAP2</i>, an R2R3 MYB transcription factor gene, is highly expressed in “Empress of India”, a nasturtium variety with high anthocyanin content, while the expression of <i>TmPAP2</i> in <i>Arabidopsis</i> led to the overproduction of anthocyanins. Protoplast transfection shows that TmPAP2 functions as a transcription activator; consistent with this finding, some of the biosynthesis genes in the general phenylpropanoid pathway and anthocyanin biosynthesis pathway were highly expressed in “Empress of India” and the <i>35S:TmPAP2</i> transgenic <i>Arabidopsis</i> plants. However, protoplast transfection indicates that TmPAP2 may not be able to form an MBW complex with TmGL3 and TmTTG1. These results suggest that TmPAP2 may function alone as a key regulator of anthocyanin biosynthesis in nasturtiums.
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spelling doaj.art-ca7d14220d8546c1a9f9a3ed16a2bc732023-12-02T00:32:32ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672022-10-0123201239510.3390/ijms232012395<i>Tropaeolum majus</i> R2R3 MYB Transcription Factor TmPAP2 Functions as a Positive Regulator of Anthocyanin BiosynthesisXiaoping Wang0Wei Wang1Siyu Chen2Yuji Lian3Shucai Wang4Laboratory of Plant Molecular Genetics & Crop Gene Editing, School of Life Sciences, Linyi University, Linyi 276000, ChinaLaboratory of Plant Molecular Genetics & Crop Gene Editing, School of Life Sciences, Linyi University, Linyi 276000, ChinaLaboratory of Plant Molecular Genetics & Crop Gene Editing, School of Life Sciences, Linyi University, Linyi 276000, ChinaLaboratory of Plant Molecular Genetics & Crop Gene Editing, School of Life Sciences, Linyi University, Linyi 276000, ChinaLaboratory of Plant Molecular Genetics & Crop Gene Editing, School of Life Sciences, Linyi University, Linyi 276000, ChinaAnthocyanins are an important group of water-soluble and non-toxic natural pigments with antioxidant and anti-inflammatory properties that can be found in flowers, vegetables, and fruits. Anthocyanin biosynthesis is regulated by several different types of transcription factors, including the WD40-repeat protein Transparent Testa Glabra 1 (TTG1), the bHLH transcription factor Transparent Testa 8 (TT8), Glabra3 (GL3), Enhancer of GL3 (EGL3), and the R2R3 MYB transcription factor Production of Anthocyanin Pigment 1 (PAP1), PAP2, MYB113, and MYB114, which are able to form MYB-bHLH-WD40 (MBW) complexes to regulate the expression of late biosynthesis genes (LBGs) in the anthocyanin biosynthesis pathway. Nasturtium (<i>Tropaeolum majus</i>) is an edible flower plant that offers many health benefits, as it contains numerous medicinally important ingredients, including anthocyanins. By a comparative examination of the possible anthocyanin biosynthesis regulator genes in nasturtium varieties with different anthocyanin contents, we found that <i>TmPAP2</i>, an R2R3 MYB transcription factor gene, is highly expressed in “Empress of India”, a nasturtium variety with high anthocyanin content, while the expression of <i>TmPAP2</i> in <i>Arabidopsis</i> led to the overproduction of anthocyanins. Protoplast transfection shows that TmPAP2 functions as a transcription activator; consistent with this finding, some of the biosynthesis genes in the general phenylpropanoid pathway and anthocyanin biosynthesis pathway were highly expressed in “Empress of India” and the <i>35S:TmPAP2</i> transgenic <i>Arabidopsis</i> plants. However, protoplast transfection indicates that TmPAP2 may not be able to form an MBW complex with TmGL3 and TmTTG1. These results suggest that TmPAP2 may function alone as a key regulator of anthocyanin biosynthesis in nasturtiums.https://www.mdpi.com/1422-0067/23/20/12395nasturtium<i>Tropaeolum majus</i>anthocyanin biosynthesistranscription factorsTmPAP2TmTTG1
spellingShingle Xiaoping Wang
Wei Wang
Siyu Chen
Yuji Lian
Shucai Wang
<i>Tropaeolum majus</i> R2R3 MYB Transcription Factor TmPAP2 Functions as a Positive Regulator of Anthocyanin Biosynthesis
International Journal of Molecular Sciences
nasturtium
<i>Tropaeolum majus</i>
anthocyanin biosynthesis
transcription factors
TmPAP2
TmTTG1
title <i>Tropaeolum majus</i> R2R3 MYB Transcription Factor TmPAP2 Functions as a Positive Regulator of Anthocyanin Biosynthesis
title_full <i>Tropaeolum majus</i> R2R3 MYB Transcription Factor TmPAP2 Functions as a Positive Regulator of Anthocyanin Biosynthesis
title_fullStr <i>Tropaeolum majus</i> R2R3 MYB Transcription Factor TmPAP2 Functions as a Positive Regulator of Anthocyanin Biosynthesis
title_full_unstemmed <i>Tropaeolum majus</i> R2R3 MYB Transcription Factor TmPAP2 Functions as a Positive Regulator of Anthocyanin Biosynthesis
title_short <i>Tropaeolum majus</i> R2R3 MYB Transcription Factor TmPAP2 Functions as a Positive Regulator of Anthocyanin Biosynthesis
title_sort i tropaeolum majus i r2r3 myb transcription factor tmpap2 functions as a positive regulator of anthocyanin biosynthesis
topic nasturtium
<i>Tropaeolum majus</i>
anthocyanin biosynthesis
transcription factors
TmPAP2
TmTTG1
url https://www.mdpi.com/1422-0067/23/20/12395
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