StMYB44 negatively regulates anthocyanin biosynthesis at high temperatures in tuber flesh of potato

Abstract High temperatures are known to reduce anthocyanin accumulation in a number of diverse plant species. In potato (Solanum tuberosum L.), high temperature significantly reduces tuber anthocyanin pigment content. However, the mechanism of anthocyanin biosynthesis in potato tuber under heat stress remains unknown. Here we show that high temperature causes reduction of anthocyanin biosynthesis in both potato tuber skin and flesh, with white areas forming between the vasculature and periderm. Heat stress reduced the expression of the R2R3 MYB transcription factors (TFs) StAN1 and StbHLH1, members of the transcriptional complex responsible for coordinated regulation of the skin and flesh pigmentation, as well as anthocyanin biosynthetic pathway genes in white regions. However, the core phenylpropanoid pathway, lignin, and chlorogenic acid (CGA) pathway genes were up-regulated in white areas, suggesting that suppression of the anthocyanin branch may result in re-routing phenylpropanoid flux into the CGA or lignin biosynthesis branches. Two R2R3 MYB TFs, StMYB44-1 and StMYB44-2, were highly expressed in white regions under high temperature. In transient assays, StMYB44 represses anthocyanin accumulation in leaves of Nicotiana tabacum and N. benthamiana by directly suppressing the activity of the dihydroflavonol reductase (DFR) promoter. StMYB44-1 showed stronger repressive capacity than StMYB44-2, with both predicted proteins containing the repression-associated EAR motif with some variation. StMYB44-1 conferred repression without a requirement for a basic helix–loop–helix (bHLH) partner, suggesting a different repression mechanism from that of reported anthocyanin repressors. We propose that temperature-induced reduction of anthocyanin accumulation in potato flesh is caused by down-regulation of the activating anthocyanin regulatory complex, by enhancing the expression of flesh-specific StMYB44 and alteration of phenylpropanoid flux.

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

Plant and Cell Physiology ◽

10.1093/pcp/pcz198 ◽

2019 ◽

Vol 61 (2) ◽

pp. 318-330 ◽

Cited By ~ 7

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.

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

International Journal of Molecular Sciences ◽

10.3390/ijms222010927 ◽

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.

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

HortScience ◽

10.21273/hortsci.50.5.640 ◽

2015 ◽

Vol 50 (5) ◽

pp. 640-649 ◽

Cited By ~ 4

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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Cloning and Functional Analysis of R2R3 MYB Genes Involved in Anthocyanin Biosynthesis in Potato Tuber

ACTA AGRONOMICA SINICA ◽

10.3724/sp.j.1006.2018.01021 ◽

2018 ◽

Vol 44 (7) ◽

pp. 1021

Author(s):

Huan TAN ◽

Yu-Hui LIU ◽

Li-Xia LI ◽

Li WANG ◽

Yuan-Ming LI ◽

...

Keyword(s):

Functional Analysis ◽

Potato Tuber ◽

Anthocyanin Biosynthesis ◽

Myb Genes ◽

R2r3 Myb

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Impact of High Temperature on Oocytes and Embryos: A Review

10.48165/aru.2021.1204 ◽

2021 ◽

Vol 1 (1) ◽

pp. 32-40

Author(s):

Abubakar Muhammad Wakil ◽

Abdulhamid Abba ◽

Prem Singh Yadav

Keyword(s):

Heat Stress ◽

High Temperature ◽

High Temperatures ◽

Reproductive Tract ◽

Cell Damage ◽

Follicular Development ◽

Fertilization Rate ◽

Economic Losses ◽

Live Animal

High temperature is one of the leading factors for decline reproductive performance in livestock and other species as a result of heat stress causing severe economic losses. The embryonic death causes due to heat stress is having multifactorial mechanism in live animal. Heat stress could influence reproductive physiology through modulating blood flow to the reproductive tract, ovarian steroid concentrations and patterns of follicular development. It is difficult for embryos to survive in the increase an oviductal and uterine temperature which is coincident with heat stress. In vitro culture of embryos at high temperatures has been reported to affect embryonic development. Similarly, increased in vitroculture temperatures can compromise oocyte activity and reduce fertilization rate. Studies have demonstrated that there were lethal effects of heat shock on in vitro cultured embryos of cattle at 41.0 – 43.0°C. However, these experimental temperatures are higher than those generally experienced by heat-stressed cows which ultimately reduced their fertility. Furthermore, a lot of research have been conducted in livestock species all indicating that exposure to high temperature is detrimental to oocytes and embryonic developmental processes as it leads to cell damage and may interfere with oocyte maturation, and fertilization process. It concludes that the longer exposure of oocytes and embryos to high temperatures causes more damage to oocytes and embryos.

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Plastic responses of survival and fertility following heat stress in pupal and adult Drosophila virilis

10.22541/au.163257890.03873739/v1 ◽

2021 ◽

Author(s):

Benjamin Walsh ◽

Steven Parratt ◽

Natasha Mannion ◽

Rhonda Snook ◽

Amanda Bretman ◽

...

Keyword(s):

Heat Stress ◽

High Temperature ◽

Temperature Stress ◽

High Temperatures ◽

Male Fertility ◽

Thermal Tolerance ◽

Drosophila Virilis ◽

Life History Stage ◽

Heat Hardening ◽

The Impact

The impact of rising global temperatures on survival and reproduction is putting many species at risk of extinction. In particular, it has recently been shown that thermal effects on reproduction, especially limits to male fertility, can underpin species distributions in insects. However, the physiological factors influencing fertility at high temperatures are poorly understood. Key factors that affect somatic thermal tolerance such as hardening, the ability to phenotypically increase thermal tolerance after a mild heat shock, and the differential impact of temperature on different life stages, are largely unexplored for thermal fertility tolerance. Here, we examine the impact of high temperatures on male fertility in the cosmopolitan fruit fly Drosophila virilis. We first determined whether temperature stress at either the pupal or adult life-history stage impacts fertility. We then tested the capacity for heat-hardening to mitigate heat-induced sterility. We found that thermal stress reduces fertility in different ways in pupae and adults. Pupal heat stress delays sexual maturity, whereas males heated as adults can reproduce initially following heat stress, but lose the ability to produce offspring. We also found evidence that while heat-hardening in D. virilis can improve high temperature survival, there is no significant protective impact of this same hardening treatment on fertility. These results suggest that males may be unable to prevent the costs of high temperature stress on fertility through heat-hardening which limits a species’ ability to quickly and effectively reduce fertility loss in the face of short-term high temperature events.

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The combination of R2R3-MYB gene AmRosea1 and hairy root culture is a useful tool for rapidly induction and production of anthocyanins in Antirrhinum majus L

AMB Express ◽

10.1186/s13568-021-01286-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Chunlan Piao ◽

Jinguo Wu ◽

Min-Long Cui

Keyword(s):

Hairy Roots ◽

Anthocyanin Biosynthesis ◽

Ectopic Expression ◽

Root Culture ◽

Hairy Root Culture ◽

Anthocyanin Accumulation ◽

Structural Genes ◽

Myb Gene ◽

Transformed Hairy Roots ◽

R2r3 Myb

AbstractAnthocyanins are the largest group of water-soluble pigments and beneficial for human health. Although most plants roots have the potential to express natural biosynthesis pathways required to produce specialized metabolites such as anthocyanins, the anthocyanin synthesis is specifically silenced in roots. To explore the molecular mechanism of absence and production ability of anthocyanin in the roots, investigated the effect of a bHLH gene AmDelila, and an R2R3-MYB gene AmRosea1, which are the master regulators of anthocyanin biosynthesis in Antirrhinum majus flowers, by expressing these genes in transformed hairy roots of A. majus. Co-ectopic expression of both AmDelila and AmRosea1 significantly upregulated the expression of the key target structural genes in the anthocyanin biosynthesis pathway. Furthermore, this resulted in strongly enhanced anthocyanin accumulation in transformed hairy roots. Ectopic expression of AmDelila alone did not gives rise to any significant anthocyanin accumulation, however, ectopic expression of AmRosea1 alone clearly upregulated expression of the main structural genes as well as greatly promoted anthocyanin accumulation in transformed hairy roots, where the contents reached 0.773–2.064 mg/g fresh weight. These results suggest that AmRosea1 plays a key role in the regulatory network in controlling the initiation of anthocyanin biosynthesis in roots, and the combination of AmRosea1 and hairy root culture is a powerful tool to study and production of anthocyanins in the roots of A. majus.

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

Genes ◽

10.3390/genes10100777 ◽

2019 ◽

Vol 10 (10) ◽

pp. 777 ◽

Cited By ~ 3

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.

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Light- and Temperature-Induced Expression of an R2R3-MYB Gene Regulates Anthocyanin Biosynthesis in Red-Fleshed Kiwifruit

International Journal of Molecular Sciences ◽

10.3390/ijms20205228 ◽

2019 ◽

Vol 20 (20) ◽

pp. 5228 ◽

Cited By ~ 1

Author(s):

Min Yu ◽

Yuping Man ◽

Yanchang Wang

Keyword(s):

Transcriptional Activation ◽

Anthocyanin Biosynthesis ◽

Physiological Role ◽

Regulatory Function ◽

Anthocyanin Content ◽

Anthocyanin Accumulation ◽

Virus Induced Gene Silencing ◽

Highly Correlated ◽

Myb Genes ◽

R2r3 Myb

The R2R3 MYB genes associated with the flavonoid/anthocyanidin pathway feature two repeats, and represent the most abundant classes of MYB genes in plants; however, the physiological role and regulatory function of most R2R3 MYBs remain poorly understood in kiwifruit (Actinidia). Here, genome-wide analysis identified 155 R2R3-MYBs in the ‘Red 5′ version of the Actinidia chinensis genome. Out of 36 anthocyanin-related AccR2R3-MYBs, AcMYB10 was the most highly expressed in inner pericarp of red-fleshed kiwifruit. The expression of AcMYB10 was highly correlated with anthocyanin accumulation in natural pigmentation during fruit ripening and light-/temperature-induced pigmentation in the callus. AcMYB10 is localized in the nuclei and has transcriptional activation activity. Overexpression of AcMYB10 elevates anthocyanin accumulation in transgenic A. chinensis. In comparison, A. chinensis fruit infiltrated with virus-induced gene silencing showed delayed red coloration, lower anthocyanin content, and lower expression of AcMYB10. The transient expression experiment in Nicotiana tabacum leaves and Actinidia arguta fruit indicated the interaction of AcMYB10 with AcbHLH42 might strongly activate anthocyanin biosynthesis by activating the transcription of AcLDOX and AcF3GT. In conclusion, this study provides novel molecular information about R2R3-MYBs in kiwifruit, advances our understanding of light- and temperature-induced anthocyanin accumulation, and demonstrates the important function of AcMYB10 in the biosynthesis of anthocyanin in kiwifruit.

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Identification of Two Novel R2R3-MYB Transcription factors, PsMYB114L and PsMYB12L, Related to Anthocyanin Biosynthesis in Paeonia suffruticosa

International Journal of Molecular Sciences ◽

10.3390/ijms20051055 ◽

2019 ◽

Vol 20 (5) ◽

pp. 1055 ◽

Cited By ~ 4

Author(s):

Xinpeng Zhang ◽

Zongda Xu ◽

Xiaoyan Yu ◽

Lanyong Zhao ◽

Mingyuan Zhao ◽

...

Keyword(s):

Transcription Factors ◽

Anthocyanin Biosynthesis ◽

Critical Role ◽

Flower Color ◽

Anthocyanin Accumulation ◽

Paeonia Suffruticosa ◽

Myb Transcription Factors ◽

Transgenic Lines ◽

R2r3 Myb ◽

R2r3 Myb Transcription Factors

Flower color is a charming phenotype with very important ornamental and commercial values. Anthocyanins play a critical role in determining flower color pattern formation, and their biosynthesis is typically regulated by R2R3-MYB transcription factors (TFs). Paeonia suffruticosa is a famous ornamental plant with colorful flowers. However, little is known about the R2R3-MYB TFs that regulate anthocyanin accumulation in P. suffruticosa. In the present study, two R2R3-MYB TFs, namely, PsMYB114L and PsMYB12L, were isolated from the petals of P. suffruticosa ‘Shima Nishiki’ and functionally characterized. Sequence analysis suggested that PsMYB114L contained a bHLH-interaction motif, whereas PsMYB12L contained two flavonol-specific motifs (SG7 and SG7-2). Subsequently, the in vivo function of PsMYB114L and PsMYB12L was investigated by their heterologous expression in Arabidopsis thaliana and apple calli. In transgenic Arabidopsis plants, overexpression of PsMYB114L and of PsMYB12L caused a significantly higher accumulation of anthocyanins, resulting in purple-red leaves. Transgenic apple calli overexpressing PsMYB114L and PsMYB12L also significantly enhanced the anthocyanins content and resulted in a change in the callus color to red. Meanwhile, gene expression analysis in A. thaliana and apple calli suggested that the expression levels of the flavonol synthase (MdFLS) and anthocyanidin reductase (MdANR) genes were significantly downregulated and the dihydroflavonol 4-reductase (AtDFR) and anthocyanin synthase (AtANS) genes were significantly upregulated in transgenic lines of PsMYB114L. Moreover, the expression level of the FLS gene (MdFLS) was significantly downregulated and the DFR (AtDFR/MdDFR) and ANS (AtANS/MdANS) genes were all significantly upregulated in transgenic lines plants of PsMYB12L. These results indicate that PsMYB114L and PsMYB12L both enhance anthocyanin accumulation by specifically regulating the expression of some anthocyanin biosynthesis-related genes in different plant species. Together, these results provide a valuable resource with which to further study the regulatory mechanism of anthocyanin biosynthesis in P. suffruticosa and for the breeding of tree peony cultivars with novel and charming flower colors.

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