scholarly journals CsMYB3 and CsRuby1 form an ‘Activator-and-Repressor’ Loop for the Regulation of Anthocyanin Biosynthesis in Citrus

2019 ◽  
Vol 61 (2) ◽  
pp. 318-330 ◽  
Author(s):  
Ding Huang ◽  
Zhouzhou Tang ◽  
Jialing Fu ◽  
Yue Yuan ◽  
Xiuxin Deng ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Anthocyanin Biosynthesis ◽  
Myb Transcription Factor ◽  
Nitrogen Stress ◽  
Loop Model ◽  
Anthocyanin Accumulation ◽  
Promoter Activation ◽  
R2r3 Myb ◽  
Activation Capacity ◽  
Anthocyanin Biosynthetic Genes

Abstract Anthocyanins are preferentially accumulated in certain tissues of particular species of citrus. A R2R3-MYB transcription factor (named Ruby1) has been well documented as an activator of citrus anthocyanin biosynthesis. In this study, we characterized CsMYB3, a transcriptional repressor that regulates anthocyanin biosynthesis in citrus. CsMYB3 was expressed in anthocyanin-pigmented tissues, and the expression was closely associated with that of Ruby1, which is a key anthocyanin activator. Overexpression of CsMYB3 in Arabidopsis resulted in a decrease in anthocyanins under nitrogen stress. Overexpression of CsMYB3 in the background of CsRuby1-overexpressing strawberry and Arabidopsis reduced the anthocyanin accumulation level. Transient promoter activation assays revealed that CsMYB3 could repress the activation capacity of the complex formed by CsRuby1/CsbHLH1 for the anthocyanin biosynthetic genes. Moreover, CsMYB3 could be transcriptionally activated by CsRuby1 via promoter binding, thus forming an ‘activator-and-repressor’ loop to regulate anthocyanin biosynthesis in citrus. This study shows that CsMYB3 plays a repressor role in the regulation of anthocyanin biosynthesis and proposes an ‘activator-and-repressor’ loop model constituted by CsRuby1 and CsMYB3 in the regulation of anthocyanin biosynthesis in citrus.

scholarly journals Loss of the R2R3 MYB Transcription Factor RsMYB1 Shapes Anthocyanin Biosynthesis and Accumulation in Raphanus sativus

2021 ◽  
Vol 22 (20) ◽  
pp. 10927
Author(s):  
Da-Hye Kim ◽  
Jundae Lee ◽  
JuHee Rhee ◽  
Jong-Yeol Lee ◽  
Sun-Hyung Lim
Keyword(s):  
Transcription Factor ◽  
Raphanus Sativus ◽  
Anthocyanin Biosynthesis ◽  
Antioxidant Properties ◽  
Myb Transcription Factor ◽  
Anthocyanin Accumulation ◽  
Truncated Protein ◽  
Frame Shift ◽  
Frame Shift Mutation ◽  
R2r3 Myb

The red or purple color of radish (Raphanus sativus L.) taproots is due to anthocyanins, which have nutritional and aesthetic value, as well as antioxidant properties. Moreover, the varied patterns and levels of anthocyanin accumulation in radish roots make them an interesting system for studying the transcriptional regulation of anthocyanin biosynthesis. The R2R3 MYB transcription factor RsMYB1 is a key positive regulator of anthocyanin biosynthesis in radish. Here, we isolated an allele of RsMYB1, named RsMYB1Short, in radish cultivars with white taproots. The RsMYB1Short allele carried a 4 bp insertion in the first exon causing a frame-shift mutation of RsMYB1, generating a truncated protein with only a partial R2 domain at the N-terminus. Unlike RsMYB1Full, RsMYB1Short was localized to the nucleus and the cytoplasm and failed to interact with their cognate partner RsTT8. Transient expression of genomic or cDNA sequences for RsMYB1Short in radish cotyledons failed to induce anthocyanin accumulation, but that for RsMYB1Full activated it. Additionally, RsMYB1Short showed the lost ability to induce pigment accumulation and to enhance the transcript level of anthocyanin biosynthetic genes, while RsMYB1Full promoted both processes when co-expressed with RsTT8 in tobacco leaves. As the result of the transient assay, co-expressing RsTT8 and RsMYB1Full, but not RsMYB1Short, also enhanced the promoter activity of RsCHS and RsDFR. We designed a molecular marker for RsMYB1 genotyping, and revealed that the RsMYB1Short allele is common in white radish cultivars, underscoring the importance of variation at the RsMYB1 locus in anthocyanin biosynthesis in the radish taproot. Together, these results indicate that the nonsense mutation of RsMYB1 generated the truncated protein, RsMYB1Short, that had the loss of ability to regulate anthocyanin biosynthesis. Our findings highlight that the frame shift mutation of RsMYB1 plays a key role in anthocyanin biosynthesis in the radish taproot.

scholarly journals Ectopic Expression of Multiple Chrysanthemum (Chrysanthemum × morifolium) R2R3-MYB Transcription Factor Genes Regulates Anthocyanin Accumulation in Tobacco

Genes ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 777 ◽  
Author(s):  
Yan Hong ◽  
Mengling Li ◽  
Silan Dai
Keyword(s):  
Transcription Factor ◽  
Anthocyanin Biosynthesis ◽  
Functional Divergence ◽  
Ectopic Expression ◽  
Chrysanthemum Morifolium ◽  
Amino Acid Sequences ◽  
Regulatory Function ◽  
Myb Transcription Factor ◽  
Anthocyanin Accumulation ◽  
R2r3 Myb

The generation of chrysanthemum (Chrysanthemum × morifolium) flower color is mainly attributed to the accumulation of anthocyanins. In the anthocyanin biosynthetic pathway in chrysanthemum, although all of the structural genes have been cloned, the regulatory function of R2R3-MYB transcription factor (TF) genes, which play a crucial role in determining anthocyanin accumulation in many ornamental crops, still remains unclear. In our previous study, four light-induced R2R3-MYB TF genes in chrysanthemum were identified using transcriptomic sequencing. In the present study, we further investigated the regulatory functions of these genes via phylogenetic and alignment analyses of amino acid sequences, which were subsequently verified by phenotypic, pigmental, and structural gene expression analyses in transgenic tobacco lines. As revealed by phylogenetic and alignment analyses, CmMYB4 and CmMYB5 were phenylpropanoid and flavonoid repressor R2R3-MYB genes, respectively, while CmMYB6 was an activator of anthocyanin biosynthesis, and CmMYB7 was involved in regulating flavonol biosynthesis. Compared with wild-type plants, the relative anthocyanin contents in the 35S:CmMYB4 and 35S:CmMYB5 tobacco lines significantly decreased (p < 0.05), while for 35S:CmMYB6 and 35S:CmMYB7, the opposite result was obtained. Both in the 35S:CmMYB4 and 35S:CmMYB5 lines, the relative expression of several anthocyanin biosynthetic genes in tobacco was significantly downregulated (p < 0.05); on the contrary, several genes were upregulated in the 35S:CmMYB6 and 35S:CmMYB7 lines. These results indicate that CmMYB4 and CmMYB5 negatively regulate anthocyanin biosynthesis in chrysanthemum, while CmMYB6 and CmMYB7 play a positive role, which will aid in understanding the complex mechanism regulating floral pigmentation in chrysanthemum and the functional divergence of the R2R3-MYB gene family in higher plants.

An R2R3-MYB transcription factor CmMYB21 represses anthocyanin biosynthesis in color fading petals of chrysanthemum

2022 ◽  
Vol 293 ◽  
pp. 110674
Author(s):  
Yiguang Wang ◽  
Li-Jie Zhou ◽  
Yuxi Wang ◽  
Zhiqiang Geng ◽  
Baoqing Ding ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Anthocyanin Biosynthesis ◽  
Myb Transcription Factor ◽  
Color Fading ◽  
R2r3 Myb

scholarly journals A R2R3-MYB Transcription Factor, VvMYBC2L2, Functions as a Transcriptional Repressor of Anthocyanin Biosynthesis in Grapevine (Vitis vinifera L.)

Molecules ◽  
2018 ◽  
Vol 24 (1) ◽  
pp. 92 ◽  
Author(s):  
Ziguo Zhu ◽  
Guirong Li ◽  
Li Liu ◽  
Qingtian Zhang ◽  
Zhen Han ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Vitis Vinifera ◽  
Anthocyanin Biosynthesis ◽  
Transcriptional Repressor ◽  
Negative Regulator ◽  
Myb Transcription Factor ◽  
Vitis Vinifera L ◽  
Flavonoid Pathway ◽  
Leucoanthocyanidin Reductase ◽  
R2r3 Myb

In grapevine, the MYB transcription factors play an important role in the flavonoid pathway. Here, a R2R3-MYB transcription factor, VvMYBC2L2, isolated from Vitis vinifera cultivar Yatomi Rose, may be involved in anthocyanin biosynthesis as a transcriptional repressor. VvMYBC2L2 was shown to be a nuclear protein. The gene was shown to be strongly expressed in root, flower and seed tissue, but weakly expressed during the fruit development in grapevine. Overexpressing the VvMYBC2L2 gene in tobacco resulted in a very marked decrease in petal anthocyanin concentration. Expression analysis of flavonoid biosynthesis structural genes revealed that chalcone synthase (CHS), dihydroflavonol 4-reductase (DFR), leucoanthocyanidin reductase (LAR) and UDP glucose flavonoid 3-O-glucosyl transferase (UFGT) were strongly down-regulated in the VvMYBC2L2-overexpressed tobacco. In addition, transcription of the regulatory genes AN1a and AN1b was completely suppressed in transgenic plants. These results suggested that VvMYBC2L2 plays a role as a negative regulator of anthocyanin biosynthesis.

scholarly journals Induction of Anthocyanin Accumulation in Crabapple (Malus cv.) Leaves by Low Temperatures

HortScience ◽  
2015 ◽  
Vol 50 (5) ◽  
pp. 640-649 ◽  
Author(s):  
Ji Tian ◽  
Zhen-yun Han ◽  
Li-ru Zhang ◽  
Ting-Ting Song ◽  
Jie Zhang ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Anthocyanin Biosynthesis ◽  
Anthocyanin Accumulation ◽  
Human Diet ◽  
Helix Loop Helix ◽  
Leaf Coloration ◽  
Regulatory Complex ◽  
R2r3 Myb ◽  
Reverse Transcript ◽  
Anthocyanin Biosynthetic Genes

Anthocyanins are protective pigments that accumulate in plant organs such as fruits and leaves, and are nutritionally valuable components of the human diet. There is thus considerable interest in the factors that regulate synthesis. Malus crabapple leaves are rich sources of these compounds, and in this study we analyzed leaf coloration, anthocyanin levels, and the expression levels of anthocyanin biosynthetic and regulatory genes in three crabapple cultivars (Royalty, Prairifire, and Flame) following various temperature treatments. We found that low temperatures (LTs) promoted anthocyanin accumulation in ‘Royalty’ and ‘Prairifire’, leading to red leaves, but not in ‘Flame’, which accumulated abundant colorless flavonols and retained green colored leaves. Quantitative reverse transcript PCR (RT-PCR) analyses indicated that the expression of several anthocyanin biosynthetic genes was induced by LTs, as were members of the R2R3-MYB, basic helix–loop–helix (bHLH) and WD40 transcription factor families that are thought to act in a complex. We propose that anthocyanin biosynthesis is differentially regulated in the three cultivars by LTs via the expression of members of this anthocyanin regulatory complex.

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